trait Seq[A] extends Iterable[A] with collection.Seq[A] with GenericTraversableTemplate[A, Seq] with SeqLike[A, Seq[A]]
A subtrait of collection.Seq
which represents sequences
that can be mutated.
Sequences are special cases of iterable collections of class Iterable
.
Unlike iterables, sequences always have a defined order of elements.
Sequences provide a method apply
for indexing. Indices range from 0
up to the length
of
a sequence. Sequences support a number of methods to find occurrences of elements or subsequences, including
segmentLength
, prefixLength
, indexWhere
, indexOf
, lastIndexWhere
, lastIndexOf
,
startsWith
, endsWith
, indexOfSlice
.
Another way to see a sequence is as a PartialFunction
from Int
values
to the element type of the sequence. The isDefinedAt
method of a sequence
returns true
for the interval from 0
until length
.
Sequences can be accessed in reverse order of their elements, using methods
reverse
and reverseIterator
.
Sequences have two principal subtraits, IndexedSeq
and LinearSeq
, which give different guarantees for performance.
An IndexedSeq
provides fast random-access of elements and a fast length
operation.
A LinearSeq
provides fast access only to the first element via head
, but also
has a fast tail
operation.
The class adds an update
method to collection.Seq
.
- Source
- Seq.scala
- Alphabetic
- By Inheritance
- Seq
- SeqLike
- Cloneable
- Cloneable
- Cloneable
- Seq
- SeqLike
- GenSeq
- GenSeqLike
- PartialFunction
- Function1
- Iterable
- Iterable
- IterableLike
- Equals
- GenIterable
- GenIterableLike
- Traversable
- Mutable
- Traversable
- GenTraversable
- GenericTraversableTemplate
- TraversableLike
- GenTraversableLike
- Parallelizable
- TraversableOnce
- GenTraversableOnce
- FilterMonadic
- HasNewBuilder
- AnyRef
- Any
- by CollectionsHaveToParArray
- by MonadOps
- by any2stringadd
- by StringFormat
- by Ensuring
- by ArrowAssoc
- by alternateImplicit
- Hide All
- Show All
- Public
- All
Type Members
-
class
WithFilter extends FilterMonadic[A, Repr]
A class supporting filtered operations.
A class supporting filtered operations. Instances of this class are returned by method
withFilter
.- Definition Classes
- TraversableLike
-
type
Self = Seq[A]
The type implementing this traversable
The type implementing this traversable
- Attributes
- protected[this]
- Definition Classes
- TraversableLike
Abstract Value Members
-
abstract
def
apply(idx: Int): A
Selects an element by its index in the sequence.
Selects an element by its index in the sequence.
Example:
scala> val x = List(1, 2, 3, 4, 5) x: List[Int] = List(1, 2, 3, 4, 5) scala> x(3) res1: Int = 4
- idx
The index to select.
- returns
the element of this sequence at index
idx
, where0
indicates the first element.
- Definition Classes
- SeqLike → GenSeqLike
- Exceptions thrown
IndexOutOfBoundsException
ifidx
does not satisfy0 <= idx < length
.
-
abstract
def
iterator: Iterator[A]
Creates a new iterator over all elements contained in this iterable object.
Creates a new iterator over all elements contained in this iterable object.
- returns
the new iterator
- Definition Classes
- IterableLike → GenIterableLike
-
abstract
def
length: Int
The length of the sequence.
The length of the sequence.
Note: will not terminate for infinite-sized collections.
Note:
xs.length
andxs.size
yield the same result.- returns
the number of elements in this sequence.
- Definition Classes
- SeqLike → GenSeqLike
- Exceptions thrown
IllegalArgumentException
if the length of the sequence cannot be represented in anInt
, for example,(-1 to Int.MaxValue).length
.
-
abstract
def
update(idx: Int, elem: A): Unit
Replaces element at given index with a new value.
Replaces element at given index with a new value.
- idx
the index of the element to replace.
- elem
the new value.
- Definition Classes
- SeqLike
- Exceptions thrown
IndexOutOfBoundsException
if the index is not valid.
Concrete Value Members
-
final
def
!=(arg0: Any): Boolean
Test two objects for inequality.
Test two objects for inequality.
- returns
true
if !(this == that), false otherwise.
- Definition Classes
- AnyRef → Any
-
final
def
##(): Int
Equivalent to
x.hashCode
except for boxed numeric types andnull
.Equivalent to
x.hashCode
except for boxed numeric types andnull
. For numerics, it returns a hash value which is consistent with value equality: if two value type instances compare as true, then ## will produce the same hash value for each of them. Fornull
returns a hashcode wherenull.hashCode
throws aNullPointerException
.- returns
a hash value consistent with ==
- Definition Classes
- AnyRef → Any
-
def
+(other: String): String
- Implicit
- This member is added by an implicit conversion from Seq[A] to any2stringadd[Seq[A]] performed by method any2stringadd in scala.Predef.
- Definition Classes
- any2stringadd
-
def
++[B >: A, That](that: GenTraversableOnce[B])(implicit bf: CanBuildFrom[Seq[A], B, That]): That
Returns a new traversable collection containing the elements from the left hand operand followed by the elements from the right hand operand.
Returns a new traversable collection containing the elements from the left hand operand followed by the elements from the right hand operand. The element type of the traversable collection is the most specific superclass encompassing the element types of the two operands.
- B
the element type of the returned collection.
- That
the class of the returned collection. Where possible,
That
is the same class as the current collection classRepr
, but this depends on the element typeB
being admissible for that class, which means that an implicit instance of typeCanBuildFrom[Repr, B, That]
is found.- that
the traversable to append.
- bf
an implicit value of class
CanBuildFrom
which determines the result classThat
from the current representation typeRepr
and the new element typeB
.- returns
a new collection of type
That
which contains all elements of this traversable collection followed by all elements ofthat
.
- Definition Classes
- TraversableLike → GenTraversableLike
-
def
++:[B >: A, That](that: collection.Traversable[B])(implicit bf: CanBuildFrom[Seq[A], B, That]): That
As with
++
, returns a new collection containing the elements from the left operand followed by the elements from the right operand.As with
++
, returns a new collection containing the elements from the left operand followed by the elements from the right operand.It differs from
++
in that the right operand determines the type of the resulting collection rather than the left one. Mnemonic: the COLon is on the side of the new COLlection type.Example:
scala> val x = List(1) x: List[Int] = List(1) scala> val y = LinkedList(2) y: scala.collection.mutable.LinkedList[Int] = LinkedList(2) scala> val z = x ++: y z: scala.collection.mutable.LinkedList[Int] = LinkedList(1, 2)
This overload exists because: for the implementation of
++:
we should reuse that of++
because many collections override it with more efficient versions.Since
TraversableOnce
has no++
method, we have to implement that directly, butTraversable
and down can use the overload.- B
the element type of the returned collection.
- That
the class of the returned collection. Where possible,
That
is the same class as the current collection classRepr
, but this depends on the element typeB
being admissible for that class, which means that an implicit instance of typeCanBuildFrom[Repr, B, That]
is found.- that
the traversable to append.
- bf
an implicit value of class
CanBuildFrom
which determines the result classThat
from the current representation typeRepr
and the new element typeB
.- returns
a new collection of type
That
which contains all elements of this traversable collection followed by all elements ofthat
.
- Definition Classes
- TraversableLike
-
def
++:[B](that: TraversableOnce[B]): Seq[B]
[use case] As with
++
, returns a new collection containing the elements from the left operand followed by the elements from the right operand.[use case]As with
++
, returns a new collection containing the elements from the left operand followed by the elements from the right operand.It differs from
++
in that the right operand determines the type of the resulting collection rather than the left one. Mnemonic: the COLon is on the side of the new COLlection type.Example:
scala> val x = List(1) x: List[Int] = List(1) scala> val y = LinkedList(2) y: scala.collection.mutable.LinkedList[Int] = LinkedList(2) scala> val z = x ++: y z: scala.collection.mutable.LinkedList[Int] = LinkedList(1, 2)
- B
the element type of the returned collection.
- that
the traversable to append.
- returns
a new mutable sequence which contains all elements of this mutable sequence followed by all elements of
that
.
- Definition Classes
- TraversableLike
Full Signaturedef ++:[B >: A, That](that: TraversableOnce[B])(implicit bf: CanBuildFrom[Seq[A], B, That]): That
-
def
+:(elem: A): Seq[A]
[use case] A copy of the mutable sequence with an element prepended.
[use case]A copy of the mutable sequence with an element prepended.
Note that :-ending operators are right associative (see example). A mnemonic for
+:
vs.:+
is: the COLon goes on the COLlection side.Also, the original mutable sequence is not modified, so you will want to capture the result.
Example:
scala> val x = List(1) x: List[Int] = List(1) scala> val y = 2 +: x y: List[Int] = List(2, 1) scala> println(x) List(1)
- elem
the prepended element
- returns
a new mutable sequence consisting of
elem
followed by all elements of this mutable sequence.
- Definition Classes
- SeqLike → GenSeqLike
Full Signaturedef +:[B >: A, That](elem: B)(implicit bf: CanBuildFrom[Seq[A], B, That]): That
-
def
->[B](y: B): (Seq[A], B)
- Implicit
- This member is added by an implicit conversion from Seq[A] to ArrowAssoc[Seq[A]] performed by method ArrowAssoc in scala.Predef.
- Definition Classes
- ArrowAssoc
- Annotations
- @inline()
-
def
:+(elem: A): Seq[A]
[use case] A copy of this mutable sequence with an element appended.
[use case]A copy of this mutable sequence with an element appended.
A mnemonic for
+:
vs.:+
is: the COLon goes on the COLlection side.Note: will not terminate for infinite-sized collections.
Example:
scala> val a = List(1) a: List[Int] = List(1) scala> val b = a :+ 2 b: List[Int] = List(1, 2) scala> println(a) List(1)
- elem
the appended element
- returns
a new mutable sequence consisting of all elements of this mutable sequence followed by
elem
.
- Definition Classes
- SeqLike → GenSeqLike
Full Signaturedef :+[B >: A, That](elem: B)(implicit bf: CanBuildFrom[Seq[A], B, That]): That
-
final
def
==(arg0: Any): Boolean
The expression
x == that
is equivalent toif (x eq null) that eq null else x.equals(that)
.The expression
x == that
is equivalent toif (x eq null) that eq null else x.equals(that)
.- returns
true
if the receiver object is equivalent to the argument;false
otherwise.
- Definition Classes
- AnyRef → Any
-
def
addString(b: scala.StringBuilder): scala.StringBuilder
Appends all elements of this traversable or iterator to a string builder.
Appends all elements of this traversable or iterator to a string builder. The written text consists of the string representations (w.r.t. the method
toString
) of all elements of this traversable or iterator without any separator string.Example:
scala> val a = List(1,2,3,4) a: List[Int] = List(1, 2, 3, 4) scala> val b = new StringBuilder() b: StringBuilder = scala> val h = a.addString(b) h: StringBuilder = 1234
- b
the string builder to which elements are appended.
- returns
the string builder
b
to which elements were appended.
- Definition Classes
- TraversableOnce
-
def
addString(b: scala.StringBuilder, sep: String): scala.StringBuilder
Appends all elements of this traversable or iterator to a string builder using a separator string.
Appends all elements of this traversable or iterator to a string builder using a separator string. The written text consists of the string representations (w.r.t. the method
toString
) of all elements of this traversable or iterator, separated by the stringsep
.Example:
scala> val a = List(1,2,3,4) a: List[Int] = List(1, 2, 3, 4) scala> val b = new StringBuilder() b: StringBuilder = scala> a.addString(b, ", ") res0: StringBuilder = 1, 2, 3, 4
- b
the string builder to which elements are appended.
- sep
the separator string.
- returns
the string builder
b
to which elements were appended.
- Definition Classes
- TraversableOnce
-
def
addString(b: scala.StringBuilder, start: String, sep: String, end: String): scala.StringBuilder
Appends all elements of this traversable or iterator to a string builder using start, end, and separator strings.
Appends all elements of this traversable or iterator to a string builder using start, end, and separator strings. The written text begins with the string
start
and ends with the stringend
. Inside, the string representations (w.r.t. the methodtoString
) of all elements of this traversable or iterator are separated by the stringsep
.Example:
scala> val a = List(1,2,3,4) a: List[Int] = List(1, 2, 3, 4) scala> val b = new StringBuilder() b: StringBuilder = scala> a.addString(b , "List(" , ", " , ")") res5: StringBuilder = List(1, 2, 3, 4)
- b
the string builder to which elements are appended.
- start
the starting string.
- sep
the separator string.
- end
the ending string.
- returns
the string builder
b
to which elements were appended.
- Definition Classes
- TraversableOnce
-
def
aggregate[B](z: ⇒ B)(seqop: (B, A) ⇒ B, combop: (B, B) ⇒ B): B
Aggregates the results of applying an operator to subsequent elements.
Aggregates the results of applying an operator to subsequent elements.
This is a more general form of
fold
andreduce
. It is similar tofoldLeft
in that it doesn't require the result to be a supertype of the element type. In addition, it allows parallel collections to be processed in chunks, and then combines the intermediate results.aggregate
splits the traversable or iterator into partitions and processes each partition by sequentially applyingseqop
, starting withz
(likefoldLeft
). Those intermediate results are then combined by usingcombop
(likefold
). The implementation of this operation may operate on an arbitrary number of collection partitions (even 1), socombop
may be invoked an arbitrary number of times (even 0).As an example, consider summing up the integer values of a list of chars. The initial value for the sum is 0. First,
seqop
transforms each input character to an Int and adds it to the sum (of the partition). Then,combop
just needs to sum up the intermediate results of the partitions:List('a', 'b', 'c').aggregate(0)({ (sum, ch) => sum + ch.toInt }, { (p1, p2) => p1 + p2 })
- B
the type of accumulated results
- z
the initial value for the accumulated result of the partition - this will typically be the neutral element for the
seqop
operator (e.g.Nil
for list concatenation or0
for summation) and may be evaluated more than once- seqop
an operator used to accumulate results within a partition
- combop
an associative operator used to combine results from different partitions
- Definition Classes
- TraversableOnce → GenTraversableOnce
-
def
andThen[C](k: (A) ⇒ C): PartialFunction[Int, C]
Composes this partial function with a transformation function that gets applied to results of this partial function.
Composes this partial function with a transformation function that gets applied to results of this partial function.
- C
the result type of the transformation function.
- k
the transformation function
- returns
a partial function with the same domain as this partial function, which maps arguments
x
tok(this(x))
.
- Definition Classes
- PartialFunction → Function1
-
def
applyOrElse[A1 <: Int, B1 >: A](x: A1, default: (A1) ⇒ B1): B1
Applies this partial function to the given argument when it is contained in the function domain.
Applies this partial function to the given argument when it is contained in the function domain. Applies fallback function where this partial function is not defined.
Note that expression
pf.applyOrElse(x, default)
is equivalent toif(pf isDefinedAt x) pf(x) else default(x)
except that
applyOrElse
method can be implemented more efficiently. For all partial function literals the compiler generates anapplyOrElse
implementation which avoids double evaluation of pattern matchers and guards. This makesapplyOrElse
the basis for the efficient implementation for many operations and scenarios, such as:- combining partial functions into
orElse
/andThen
chains does not lead to excessiveapply
/isDefinedAt
evaluation lift
andunlift
do not evaluate source functions twice on each invocationrunWith
allows efficient imperative-style combining of partial functions with conditionally applied actions
For non-literal partial function classes with nontrivial
isDefinedAt
method it is recommended to overrideapplyOrElse
with custom implementation that avoids doubleisDefinedAt
evaluation. This may result in better performance and more predictable behavior w.r.t. side effects.- x
the function argument
- default
the fallback function
- returns
the result of this function or fallback function application.
- Definition Classes
- PartialFunction
- Since
2.10
- combining partial functions into
-
final
def
asInstanceOf[T0]: T0
Cast the receiver object to be of type
T0
.Cast the receiver object to be of type
T0
.Note that the success of a cast at runtime is modulo Scala's erasure semantics. Therefore the expression
1.asInstanceOf[String]
will throw aClassCastException
at runtime, while the expressionList(1).asInstanceOf[List[String]]
will not. In the latter example, because the type argument is erased as part of compilation it is not possible to check whether the contents of the list are of the requested type.- returns
the receiver object.
- Definition Classes
- Any
- Exceptions thrown
ClassCastException
if the receiver object is not an instance of the erasure of typeT0
.
-
def
canEqual(that: Any): Boolean
Method called from equality methods, so that user-defined subclasses can refuse to be equal to other collections of the same kind.
Method called from equality methods, so that user-defined subclasses can refuse to be equal to other collections of the same kind.
- that
The object with which this iterable collection should be compared
- returns
true
, if this iterable collection can possibly equalthat
,false
otherwise. The test takes into consideration only the run-time types of objects but ignores their elements.
- Definition Classes
- IterableLike → Equals
-
def
clone(): Seq[A]
Create a copy of the receiver object.
Create a copy of the receiver object.
The default implementation of the
clone
method is platform dependent.- returns
a copy of the receiver object.
- Definition Classes
- Cloneable → AnyRef
- Note
not specified by SLS as a member of AnyRef
-
def
collect[B](pf: PartialFunction[A, B]): Seq[B]
[use case] Builds a new collection by applying a partial function to all elements of this mutable sequence on which the function is defined.
[use case]Builds a new collection by applying a partial function to all elements of this mutable sequence on which the function is defined.
- B
the element type of the returned collection.
- pf
the partial function which filters and maps the mutable sequence.
- returns
a new mutable sequence resulting from applying the given partial function
pf
to each element on which it is defined and collecting the results. The order of the elements is preserved.
- Definition Classes
- TraversableLike → GenTraversableLike
Full Signaturedef collect[B, That](pf: PartialFunction[A, B])(implicit bf: CanBuildFrom[Seq[A], B, That]): That
-
def
collectFirst[B](pf: PartialFunction[A, B]): Option[B]
Finds the first element of the traversable or iterator for which the given partial function is defined, and applies the partial function to it.
Finds the first element of the traversable or iterator for which the given partial function is defined, and applies the partial function to it.
Note: may not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- pf
the partial function
- returns
an option value containing pf applied to the first value for which it is defined, or
None
if none exists.
- Definition Classes
- TraversableOnce
Seq("a", 1, 5L).collectFirst({ case x: Int => x*10 }) = Some(10)
Example: -
def
combinations(n: Int): Iterator[Seq[A]]
Iterates over combinations.
Iterates over combinations. A _combination_ of length
n
is a subsequence of the original sequence, with the elements taken in order. Thus,"xy"
and"yy"
are both length-2 combinations of"xyy"
, but"yx"
is not. If there is more than one way to generate the same subsequence, only one will be returned.For example,
"xyyy"
has three different ways to generate"xy"
depending on whether the first, second, or third"y"
is selected. However, since all are identical, only one will be chosen. Which of the three will be taken is an implementation detail that is not defined.- returns
An Iterator which traverses the possible n-element combinations of this sequence.
- Definition Classes
- SeqLike
"abbbc".combinations(2) = Iterator(ab, ac, bb, bc)
Example: -
def
companion: GenericCompanion[Seq]
The factory companion object that builds instances of class
mutable.Seq
.The factory companion object that builds instances of class
mutable.Seq
. (or itsIterable
superclass where classmutable.Seq
is not aSeq
.)- Definition Classes
- Seq → Seq → GenSeq → Iterable → Iterable → GenIterable → Traversable → Traversable → GenTraversable → GenericTraversableTemplate
-
def
compose[A](g: (A) ⇒ Int): (A) ⇒ A
Composes two instances of Function1 in a new Function1, with this function applied last.
Composes two instances of Function1 in a new Function1, with this function applied last.
- A
the type to which function
g
can be applied- g
a function A => T1
- returns
a new function
f
such thatf(x) == apply(g(x))
- Definition Classes
- Function1
- Annotations
- @unspecialized()
-
def
contains[A1 >: A](elem: A1): Boolean
Tests whether this sequence contains a given value as an element.
Tests whether this sequence contains a given value as an element.
Note: may not terminate for infinite-sized collections.
- elem
the element to test.
- returns
true
if this sequence has an element that is equal (as determined by==
) toelem
,false
otherwise.
- Definition Classes
- SeqLike
-
def
containsSlice[B](that: GenSeq[B]): Boolean
Tests whether this sequence contains a given sequence as a slice.
Tests whether this sequence contains a given sequence as a slice.
Note: may not terminate for infinite-sized collections.
- that
the sequence to test
- returns
true
if this sequence contains a slice with the same elements asthat
, otherwisefalse
.
- Definition Classes
- SeqLike
-
def
copyToArray(xs: Array[A], start: Int, len: Int): Unit
[use case] Copies the elements of this mutable sequence to an array.
[use case]Copies the elements of this mutable sequence to an array. Fills the given array
xs
with at mostlen
elements of this mutable sequence, starting at positionstart
. Copying will stop once either the end of the current mutable sequence is reached, or the end of the target array is reached, orlen
elements have been copied.Note: will not terminate for infinite-sized collections.
- xs
the array to fill.
- start
the starting index.
- len
the maximal number of elements to copy.
- Definition Classes
- IterableLike → TraversableLike → TraversableOnce → GenTraversableOnce
-
def
copyToArray(xs: Array[A]): Unit
[use case] Copies the elements of this mutable sequence to an array.
[use case]Copies the elements of this mutable sequence to an array. Fills the given array
xs
with values of this mutable sequence. Copying will stop once either the end of the current mutable sequence is reached, or the end of the target array is reached.Note: will not terminate for infinite-sized collections.
- xs
the array to fill.
- Definition Classes
- TraversableOnce → GenTraversableOnce
-
def
copyToArray(xs: Array[A], start: Int): Unit
[use case] Copies the elements of this mutable sequence to an array.
[use case]Copies the elements of this mutable sequence to an array. Fills the given array
xs
with values of this mutable sequence, beginning at indexstart
. Copying will stop once either the end of the current mutable sequence is reached, or the end of the target array is reached.Note: will not terminate for infinite-sized collections.
- xs
the array to fill.
- start
the starting index.
- Definition Classes
- TraversableOnce → GenTraversableOnce
-
def
copyToBuffer[B >: A](dest: Buffer[B]): Unit
Copies all elements of this traversable or iterator to a buffer.
Copies all elements of this traversable or iterator to a buffer.
Note: will not terminate for infinite-sized collections.
- dest
The buffer to which elements are copied.
- Definition Classes
- TraversableOnce
-
def
corresponds[B](that: GenSeq[B])(p: (A, B) ⇒ Boolean): Boolean
Tests whether every element of this sequence relates to the corresponding element of another sequence by satisfying a test predicate.
Tests whether every element of this sequence relates to the corresponding element of another sequence by satisfying a test predicate.
- B
the type of the elements of
that
- that
the other sequence
- p
the test predicate, which relates elements from both sequences
- returns
true
if both sequences have the same length andp(x, y)
istrue
for all corresponding elementsx
of this sequence andy
ofthat
, otherwisefalse
.
- Definition Classes
- SeqLike → GenSeqLike
-
def
count(p: (A) ⇒ Boolean): Int
Counts the number of elements in the traversable or iterator which satisfy a predicate.
Counts the number of elements in the traversable or iterator which satisfy a predicate.
- p
the predicate used to test elements.
- returns
the number of elements satisfying the predicate
p
.
- Definition Classes
- TraversableOnce → GenTraversableOnce
-
def
diff(that: collection.Seq[A]): Seq[A]
[use case] Computes the multiset difference between this mutable sequence and another sequence.
[use case]Computes the multiset difference between this mutable sequence and another sequence.
Note: will not terminate for infinite-sized collections.
- that
the sequence of elements to remove
- returns
a new mutable sequence which contains all elements of this mutable sequence except some of occurrences of elements that also appear in
that
. If an element valuex
appears n times inthat
, then the first n occurrences ofx
will not form part of the result, but any following occurrences will.
- Definition Classes
- SeqLike → GenSeqLike
-
def
distinct: Seq[A]
Builds a new sequence from this sequence without any duplicate elements.
Builds a new sequence from this sequence without any duplicate elements.
Note: will not terminate for infinite-sized collections.
- returns
A new sequence which contains the first occurrence of every element of this sequence.
- Definition Classes
- SeqLike → GenSeqLike
-
def
drop(n: Int): Seq[A]
Selects all elements except first n ones.
Selects all elements except first n ones.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- n
the number of elements to drop from this iterable collection.
- returns
a iterable collection consisting of all elements of this iterable collection except the first
n
ones, or else the empty iterable collection, if this iterable collection has less thann
elements. Ifn
is negative, don't drop any elements.
- Definition Classes
- IterableLike → TraversableLike → GenTraversableLike
-
def
dropRight(n: Int): Seq[A]
Selects all elements except last n ones.
Selects all elements except last n ones.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- n
The number of elements to take
- returns
a iterable collection consisting of all elements of this iterable collection except the last
n
ones, or else the empty iterable collection, if this iterable collection has less thann
elements.
- Definition Classes
- IterableLike
-
def
dropWhile(p: (A) ⇒ Boolean): Seq[A]
Drops longest prefix of elements that satisfy a predicate.
Drops longest prefix of elements that satisfy a predicate.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- returns
the longest suffix of this traversable collection whose first element does not satisfy the predicate
p
.
- Definition Classes
- TraversableLike → GenTraversableLike
-
def
endsWith[B](that: GenSeq[B]): Boolean
Tests whether this sequence ends with the given sequence.
Tests whether this sequence ends with the given sequence.
Note: will not terminate for infinite-sized collections.
- that
the sequence to test
- returns
true
if this sequence hasthat
as a suffix,false
otherwise.
- Definition Classes
- SeqLike → GenSeqLike
-
def
ensuring(cond: (Seq[A]) ⇒ Boolean, msg: ⇒ Any): Seq[A]
- Implicit
- This member is added by an implicit conversion from Seq[A] to Ensuring[Seq[A]] performed by method Ensuring in scala.Predef.
- Definition Classes
- Ensuring
-
def
ensuring(cond: (Seq[A]) ⇒ Boolean): Seq[A]
- Implicit
- This member is added by an implicit conversion from Seq[A] to Ensuring[Seq[A]] performed by method Ensuring in scala.Predef.
- Definition Classes
- Ensuring
-
def
ensuring(cond: Boolean, msg: ⇒ Any): Seq[A]
- Implicit
- This member is added by an implicit conversion from Seq[A] to Ensuring[Seq[A]] performed by method Ensuring in scala.Predef.
- Definition Classes
- Ensuring
-
def
ensuring(cond: Boolean): Seq[A]
- Implicit
- This member is added by an implicit conversion from Seq[A] to Ensuring[Seq[A]] performed by method Ensuring in scala.Predef.
- Definition Classes
- Ensuring
-
final
def
eq(arg0: AnyRef): Boolean
Tests whether the argument (
that
) is a reference to the receiver object (this
).Tests whether the argument (
that
) is a reference to the receiver object (this
).The
eq
method implements an equivalence relation on non-null instances ofAnyRef
, and has three additional properties:- It is consistent: for any non-null instances
x
andy
of typeAnyRef
, multiple invocations ofx.eq(y)
consistently returnstrue
or consistently returnsfalse
. - For any non-null instance
x
of typeAnyRef
,x.eq(null)
andnull.eq(x)
returnsfalse
. null.eq(null)
returnstrue
.
When overriding the
equals
orhashCode
methods, it is important to ensure that their behavior is consistent with reference equality. Therefore, if two objects are references to each other (o1 eq o2
), they should be equal to each other (o1 == o2
) and they should hash to the same value (o1.hashCode == o2.hashCode
).- returns
true
if the argument is a reference to the receiver object;false
otherwise.
- Definition Classes
- AnyRef
- It is consistent: for any non-null instances
-
def
equals(that: Any): Boolean
The equals method for arbitrary sequences.
The equals method for arbitrary sequences. Compares this sequence to some other object.
- that
The object to compare the sequence to
- returns
true
ifthat
is a sequence that has the same elements as this sequence in the same order,false
otherwise
- Definition Classes
- GenSeqLike → Equals → Any
-
def
exists(p: (A) ⇒ Boolean): Boolean
Tests whether a predicate holds for at least one element of this iterable collection.
Tests whether a predicate holds for at least one element of this iterable collection.
Note: may not terminate for infinite-sized collections.
- p
the predicate used to test elements.
- returns
false
if this iterable collection is empty, otherwisetrue
if the given predicatep
holds for some of the elements of this iterable collection, otherwisefalse
- Definition Classes
- IterableLike → TraversableLike → TraversableOnce → GenTraversableOnce
-
def
filter(p: (A) ⇒ Boolean): Seq[A]
Selects all elements of this traversable collection which satisfy a predicate.
Selects all elements of this traversable collection which satisfy a predicate.
- p
the predicate used to test elements.
- returns
a new traversable collection consisting of all elements of this traversable collection that satisfy the given predicate
p
. The order of the elements is preserved.
- Definition Classes
- TraversableLike → GenTraversableLike
-
def
filterNot(p: (A) ⇒ Boolean): Seq[A]
Selects all elements of this traversable collection which do not satisfy a predicate.
Selects all elements of this traversable collection which do not satisfy a predicate.
- p
the predicate used to test elements.
- returns
a new traversable collection consisting of all elements of this traversable collection that do not satisfy the given predicate
p
. The order of the elements is preserved.
- Definition Classes
- TraversableLike → GenTraversableLike
-
def
finalize(): Unit
Called by the garbage collector on the receiver object when there are no more references to the object.
Called by the garbage collector on the receiver object when there are no more references to the object.
The details of when and if the
finalize
method is invoked, as well as the interaction betweenfinalize
and non-local returns and exceptions, are all platform dependent.- Attributes
- protected[lang]
- Definition Classes
- AnyRef
- Annotations
- @throws( classOf[java.lang.Throwable] )
- Note
not specified by SLS as a member of AnyRef
-
def
find(p: (A) ⇒ Boolean): Option[A]
Finds the first element of the iterable collection satisfying a predicate, if any.
Finds the first element of the iterable collection satisfying a predicate, if any.
Note: may not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- p
the predicate used to test elements.
- returns
an option value containing the first element in the iterable collection that satisfies
p
, orNone
if none exists.
- Definition Classes
- IterableLike → TraversableLike → TraversableOnce → GenTraversableOnce
-
def
flatMap[B](f: (A) ⇒ GenTraversableOnce[B]): Seq[B]
[use case] Builds a new collection by applying a function to all elements of this mutable sequence and using the elements of the resulting collections.
[use case]Builds a new collection by applying a function to all elements of this mutable sequence and using the elements of the resulting collections.
For example:
def getWords(lines: Seq[String]): Seq[String] = lines flatMap (line => line split "\\W+")
The type of the resulting collection is guided by the static type of mutable sequence. This might cause unexpected results sometimes. For example:
// lettersOf will return a Seq[Char] of likely repeated letters, instead of a Set def lettersOf(words: Seq[String]) = words flatMap (word => word.toSet) // lettersOf will return a Set[Char], not a Seq def lettersOf(words: Seq[String]) = words.toSet flatMap (word => word.toSeq) // xs will be an Iterable[Int] val xs = Map("a" -> List(11,111), "b" -> List(22,222)).flatMap(_._2) // ys will be a Map[Int, Int] val ys = Map("a" -> List(1 -> 11,1 -> 111), "b" -> List(2 -> 22,2 -> 222)).flatMap(_._2)
- B
the element type of the returned collection.
- f
the function to apply to each element.
- returns
a new mutable sequence resulting from applying the given collection-valued function
f
to each element of this mutable sequence and concatenating the results.
- Definition Classes
- TraversableLike → GenTraversableLike → FilterMonadic
Full Signaturedef flatMap[B, That](f: (A) ⇒ GenTraversableOnce[B])(implicit bf: CanBuildFrom[Seq[A], B, That]): That
-
def
flatten[B]: Seq[B]
[use case] Converts this mutable sequence of traversable collections into a mutable sequence formed by the elements of these traversable collections.
[use case]Converts this mutable sequence of traversable collections into a mutable sequence formed by the elements of these traversable collections.
The resulting collection's type will be guided by the static type of mutable sequence. For example:
val xs = List( Set(1, 2, 3), Set(1, 2, 3) ).flatten // xs == List(1, 2, 3, 1, 2, 3) val ys = Set( List(1, 2, 3), List(3, 2, 1) ).flatten // ys == Set(1, 2, 3)
- B
the type of the elements of each traversable collection.
- returns
a new mutable sequence resulting from concatenating all element mutable sequences.
- Definition Classes
- GenericTraversableTemplate
Full Signaturedef flatten[B](implicit asTraversable: (A) ⇒ GenTraversableOnce[B]): Seq[B]
-
def
fold[A1 >: A](z: A1)(op: (A1, A1) ⇒ A1): A1
Folds the elements of this traversable or iterator using the specified associative binary operator.
Folds the elements of this traversable or iterator using the specified associative binary operator.
The order in which operations are performed on elements is unspecified and may be nondeterministic.
Note: will not terminate for infinite-sized collections.
- A1
a type parameter for the binary operator, a supertype of
A
.- z
a neutral element for the fold operation; may be added to the result an arbitrary number of times, and must not change the result (e.g.,
Nil
for list concatenation, 0 for addition, or 1 for multiplication).- op
a binary operator that must be associative.
- returns
the result of applying the fold operator
op
between all the elements andz
, orz
if this traversable or iterator is empty.
- Definition Classes
- TraversableOnce → GenTraversableOnce
-
def
foldLeft[B](z: B)(op: (B, A) ⇒ B): B
Applies a binary operator to a start value and all elements of this traversable or iterator, going left to right.
Applies a binary operator to a start value and all elements of this traversable or iterator, going left to right.
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.
- B
the result type of the binary operator.
- z
the start value.
- op
the binary operator.
- returns
the result of inserting
op
between consecutive elements of this traversable or iterator, going left to right with the start valuez
on the left:op(...op(z, x_1), x_2, ..., x_n)
where
x1, ..., xn
are the elements of this traversable or iterator. Returnsz
if this traversable or iterator is empty.
- Definition Classes
- TraversableOnce → GenTraversableOnce
-
def
foldRight[B](z: B)(op: (A, B) ⇒ B): B
Applies a binary operator to all elements of this iterable collection and a start value, going right to left.
Applies a binary operator to all elements of this iterable collection and a start value, going right to left.
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered. or the operator is associative and commutative.
- B
the result type of the binary operator.
- z
the start value.
- op
the binary operator.
- returns
the result of inserting
op
between consecutive elements of this iterable collection, going right to left with the start valuez
on the right:op(x_1, op(x_2, ... op(x_n, z)...))
where
x1, ..., xn
are the elements of this iterable collection. Returnsz
if this iterable collection is empty.
- Definition Classes
- IterableLike → TraversableOnce → GenTraversableOnce
-
def
forall(p: (A) ⇒ Boolean): Boolean
Tests whether a predicate holds for all elements of this iterable collection.
Tests whether a predicate holds for all elements of this iterable collection.
Note: may not terminate for infinite-sized collections.
- p
the predicate used to test elements.
- returns
true
if this iterable collection is empty or the given predicatep
holds for all elements of this iterable collection, otherwisefalse
.
- Definition Classes
- IterableLike → TraversableLike → TraversableOnce → GenTraversableOnce
-
def
foreach(f: (A) ⇒ Unit): Unit
[use case] Applies a function
f
to all elements of this mutable sequence.[use case]Applies a function
f
to all elements of this mutable sequence.Note: this method underlies the implementation of most other bulk operations. Subclasses should re-implement this method if a more efficient implementation exists.
- f
the function that is applied for its side-effect to every element. The result of function
f
is discarded.
- Definition Classes
- IterableLike → TraversableLike → GenTraversableLike → TraversableOnce → GenTraversableOnce → FilterMonadic
Full Signaturedef foreach[U](f: (A) ⇒ U): Unit
-
def
formatted(fmtstr: String): String
Returns string formatted according to given
format
string.Returns string formatted according to given
format
string. Format strings are as forString.format
(@see java.lang.String.format).- Implicit
- This member is added by an implicit conversion from Seq[A] to StringFormat[Seq[A]] performed by method StringFormat in scala.Predef.
- Definition Classes
- StringFormat
- Annotations
- @inline()
-
def
genericBuilder[B]: Builder[B, Seq[B]]
The generic builder that builds instances of Traversable at arbitrary element types.
The generic builder that builds instances of Traversable at arbitrary element types.
- Definition Classes
- GenericTraversableTemplate
-
final
def
getClass(): Class[_]
Returns the runtime class representation of the object.
-
def
groupBy[K](f: (A) ⇒ K): immutable.Map[K, Seq[A]]
Partitions this traversable collection into a map of traversable collections according to some discriminator function.
Partitions this traversable collection into a map of traversable collections according to some discriminator function.
Note: this method is not re-implemented by views. This means when applied to a view it will always force the view and return a new traversable collection.
- K
the type of keys returned by the discriminator function.
- f
the discriminator function.
- returns
A map from keys to traversable collections such that the following invariant holds:
(xs groupBy f)(k) = xs filter (x => f(x) == k)
That is, every key
k
is bound to a traversable collection of those elementsx
for whichf(x)
equalsk
.
- Definition Classes
- TraversableLike → GenTraversableLike
-
def
grouped(size: Int): Iterator[Seq[A]]
Partitions elements in fixed size iterable collections.
Partitions elements in fixed size iterable collections.
- size
the number of elements per group
- returns
An iterator producing iterable collections of size
size
, except the last will be less than sizesize
if the elements don't divide evenly.
- Definition Classes
- IterableLike
- See also
scala.collection.Iterator, method
grouped
-
def
hasDefiniteSize: Boolean
Tests whether this traversable collection is known to have a finite size.
Tests whether this traversable collection is known to have a finite size. All strict collections are known to have finite size. For a non-strict collection such as
Stream
, the predicate returnstrue
if all elements have been computed. It returnsfalse
if the stream is not yet evaluated to the end. Non-empty Iterators usually returnfalse
even if they were created from a collection with a known finite size.Note: many collection methods will not work on collections of infinite sizes. The typical failure mode is an infinite loop. These methods always attempt a traversal without checking first that
hasDefiniteSize
returnstrue
. However, checkinghasDefiniteSize
can provide an assurance that size is well-defined and non-termination is not a concern.- returns
true
if this collection is known to have finite size,false
otherwise.
- Definition Classes
- TraversableLike → TraversableOnce → GenTraversableOnce
-
def
hashCode(): Int
Hashcodes for GenSeq produce a value from the hashcodes of all the elements of the general sequence.
Hashcodes for GenSeq produce a value from the hashcodes of all the elements of the general sequence.
- returns
the hash code value for this object.
- Definition Classes
- GenSeqLike → Any
-
def
head: A
Selects the first element of this iterable collection.
Selects the first element of this iterable collection.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- returns
the first element of this iterable collection.
- Definition Classes
- IterableLike → TraversableLike → GenTraversableLike
- Exceptions thrown
NoSuchElementException
if the iterable collection is empty.
-
def
headOption: Option[A]
Optionally selects the first element.
Optionally selects the first element.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- returns
the first element of this traversable collection if it is nonempty,
None
if it is empty.
- Definition Classes
- TraversableLike → GenTraversableLike
-
def
indexOf(elem: A, from: Int): Int
[use case] Finds index of first occurrence of some value in this mutable sequence after or at some start index.
[use case]Finds index of first occurrence of some value in this mutable sequence after or at some start index.
Note: may not terminate for infinite-sized collections.
- elem
the element value to search for.
- from
the start index
- returns
the index
>= from
of the first element of this mutable sequence that is equal (as determined by==
) toelem
, or-1
, if none exists.
- Definition Classes
- GenSeqLike
-
def
indexOf(elem: A): Int
[use case] Finds index of first occurrence of some value in this mutable sequence.
[use case]Finds index of first occurrence of some value in this mutable sequence.
Note: may not terminate for infinite-sized collections.
- elem
the element value to search for.
- returns
the index of the first element of this mutable sequence that is equal (as determined by
==
) toelem
, or-1
, if none exists.
- Definition Classes
- GenSeqLike
Full Signaturedef indexOf[B >: A](elem: B): Int
-
def
indexOfSlice[B >: A](that: GenSeq[B], from: Int): Int
Finds first index after or at a start index where this sequence contains a given sequence as a slice.
Finds first index after or at a start index where this sequence contains a given sequence as a slice.
Note: may not terminate for infinite-sized collections.
- that
the sequence to test
- from
the start index
- returns
the first index
>= from
such that the elements of this sequence starting at this index match the elements of sequencethat
, or-1
of no such subsequence exists.
- Definition Classes
- SeqLike
-
def
indexOfSlice[B >: A](that: GenSeq[B]): Int
Finds first index where this sequence contains a given sequence as a slice.
Finds first index where this sequence contains a given sequence as a slice.
Note: may not terminate for infinite-sized collections.
- that
the sequence to test
- returns
the first index such that the elements of this sequence starting at this index match the elements of sequence
that
, or-1
of no such subsequence exists.
- Definition Classes
- SeqLike
-
def
indexWhere(p: (A) ⇒ Boolean, from: Int): Int
Finds index of the first element satisfying some predicate after or at some start index.
Finds index of the first element satisfying some predicate after or at some start index.
Note: may not terminate for infinite-sized collections.
- p
the predicate used to test elements.
- from
the start index
- returns
the index
>= from
of the first element of this sequence that satisfies the predicatep
, or-1
, if none exists.
- Definition Classes
- SeqLike → GenSeqLike
-
def
indexWhere(p: (A) ⇒ Boolean): Int
Finds index of first element satisfying some predicate.
Finds index of first element satisfying some predicate.
Note: may not terminate for infinite-sized collections.
- p
the predicate used to test elements.
- returns
the index of the first element of this general sequence that satisfies the predicate
p
, or-1
, if none exists.
- Definition Classes
- GenSeqLike
-
def
indices: immutable.Range
Produces the range of all indices of this sequence.
Produces the range of all indices of this sequence.
- returns
a
Range
value from0
to one less than the length of this sequence.
- Definition Classes
- SeqLike
-
def
init: Seq[A]
Selects all elements except the last.
Selects all elements except the last.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- returns
a traversable collection consisting of all elements of this traversable collection except the last one.
- Definition Classes
- TraversableLike → GenTraversableLike
- Exceptions thrown
UnsupportedOperationException
if the traversable collection is empty.
-
def
inits: Iterator[Seq[A]]
Iterates over the inits of this traversable collection.
Iterates over the inits of this traversable collection. The first value will be this traversable collection and the final one will be an empty traversable collection, with the intervening values the results of successive applications of
init
.- returns
an iterator over all the inits of this traversable collection
- Definition Classes
- TraversableLike
List(1,2,3).inits = Iterator(List(1,2,3), List(1,2), List(1), Nil)
Example: -
def
intersect(that: collection.Seq[A]): Seq[A]
[use case] Computes the multiset intersection between this mutable sequence and another sequence.
[use case]Computes the multiset intersection between this mutable sequence and another sequence.
Note: may not terminate for infinite-sized collections.
- that
the sequence of elements to intersect with.
- returns
a new mutable sequence which contains all elements of this mutable sequence which also appear in
that
. If an element valuex
appears n times inthat
, then the first n occurrences ofx
will be retained in the result, but any following occurrences will be omitted.
- Definition Classes
- SeqLike → GenSeqLike
-
def
isDefinedAt(idx: Int): Boolean
Tests whether this general sequence contains given index.
Tests whether this general sequence contains given index.
The implementations of methods
apply
andisDefinedAt
turn aSeq[A]
into aPartialFunction[Int, A]
.- idx
the index to test
- returns
true
if this general sequence contains an element at positionidx
,false
otherwise.
- Definition Classes
- GenSeqLike
-
def
isEmpty: Boolean
Tests whether this sequence is empty.
Tests whether this sequence is empty.
- returns
true
if the sequence contain no elements,false
otherwise.
- Definition Classes
- SeqLike → IterableLike → TraversableLike → TraversableOnce → GenTraversableOnce
-
final
def
isInstanceOf[T0]: Boolean
Test whether the dynamic type of the receiver object is
T0
.Test whether the dynamic type of the receiver object is
T0
.Note that the result of the test is modulo Scala's erasure semantics. Therefore the expression
1.isInstanceOf[String]
will returnfalse
, while the expressionList(1).isInstanceOf[List[String]]
will returntrue
. In the latter example, because the type argument is erased as part of compilation it is not possible to check whether the contents of the list are of the specified type.- returns
true
if the receiver object is an instance of erasure of typeT0
;false
otherwise.
- Definition Classes
- Any
-
final
def
isTraversableAgain: Boolean
Tests whether this traversable collection can be repeatedly traversed.
Tests whether this traversable collection can be repeatedly traversed.
- returns
true
- Definition Classes
- TraversableLike → GenTraversableLike → GenTraversableOnce
-
def
last: A
Selects the last element.
Selects the last element.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- returns
The last element of this traversable collection.
- Definition Classes
- TraversableLike → GenTraversableLike
- Exceptions thrown
NoSuchElementException
If the traversable collection is empty.
-
def
lastIndexOf(elem: A, end: Int): Int
[use case] Finds index of last occurrence of some value in this mutable sequence before or at a given end index.
[use case]Finds index of last occurrence of some value in this mutable sequence before or at a given end index.
- elem
the element value to search for.
- end
the end index.
- returns
the index
<= end
of the last element of this mutable sequence that is equal (as determined by==
) toelem
, or-1
, if none exists.
- Definition Classes
- GenSeqLike
-
def
lastIndexOf(elem: A): Int
[use case] Finds index of last occurrence of some value in this mutable sequence.
[use case]Finds index of last occurrence of some value in this mutable sequence.
Note: will not terminate for infinite-sized collections.
- elem
the element value to search for.
- returns
the index of the last element of this mutable sequence that is equal (as determined by
==
) toelem
, or-1
, if none exists.
- Definition Classes
- GenSeqLike
Full Signaturedef lastIndexOf[B >: A](elem: B): Int
-
def
lastIndexOfSlice[B >: A](that: GenSeq[B], end: Int): Int
Finds last index before or at a given end index where this sequence contains a given sequence as a slice.
Finds last index before or at a given end index where this sequence contains a given sequence as a slice.
- that
the sequence to test
- end
the end index
- returns
the last index
<= end
such that the elements of this sequence starting at this index match the elements of sequencethat
, or-1
of no such subsequence exists.
- Definition Classes
- SeqLike
-
def
lastIndexOfSlice[B >: A](that: GenSeq[B]): Int
Finds last index where this sequence contains a given sequence as a slice.
Finds last index where this sequence contains a given sequence as a slice.
Note: will not terminate for infinite-sized collections.
- that
the sequence to test
- returns
the last index such that the elements of this sequence starting a this index match the elements of sequence
that
, or-1
of no such subsequence exists.
- Definition Classes
- SeqLike
-
def
lastIndexWhere(p: (A) ⇒ Boolean, end: Int): Int
Finds index of last element satisfying some predicate before or at given end index.
Finds index of last element satisfying some predicate before or at given end index.
- p
the predicate used to test elements.
- returns
the index
<= end
of the last element of this sequence that satisfies the predicatep
, or-1
, if none exists.
- Definition Classes
- SeqLike → GenSeqLike
-
def
lastIndexWhere(p: (A) ⇒ Boolean): Int
Finds index of last element satisfying some predicate.
Finds index of last element satisfying some predicate.
Note: will not terminate for infinite-sized collections.
- p
the predicate used to test elements.
- returns
the index of the last element of this general sequence that satisfies the predicate
p
, or-1
, if none exists.
- Definition Classes
- GenSeqLike
-
def
lastOption: Option[A]
Optionally selects the last element.
Optionally selects the last element.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- returns
the last element of this traversable collection$ if it is nonempty,
None
if it is empty.
- Definition Classes
- TraversableLike → GenTraversableLike
-
def
lengthCompare(len: Int): Int
Compares the length of this sequence to a test value.
Compares the length of this sequence to a test value.
- len
the test value that gets compared with the length.
- returns
A value
x
wherex < 0 if this.length < len x == 0 if this.length == len x > 0 if this.length > len
The method as implemented here does not call
length
directly; its running time isO(length min len)
instead ofO(length)
. The method should be overwritten if computinglength
is cheap.
- Definition Classes
- SeqLike
-
def
lift: (Int) ⇒ Option[A]
Turns this partial function into a plain function returning an
Option
result.Turns this partial function into a plain function returning an
Option
result.- returns
a function that takes an argument
x
toSome(this(x))
ifthis
is defined forx
, and toNone
otherwise.
- Definition Classes
- PartialFunction
- See also
Function.unlift
-
def
map[B](f: (A) ⇒ B): Seq[B]
[use case] Builds a new collection by applying a function to all elements of this mutable sequence.
[use case]Builds a new collection by applying a function to all elements of this mutable sequence.
- B
the element type of the returned collection.
- f
the function to apply to each element.
- returns
a new mutable sequence resulting from applying the given function
f
to each element of this mutable sequence and collecting the results.
- Definition Classes
- TraversableLike → GenTraversableLike → FilterMonadic
Full Signaturedef map[B, That](f: (A) ⇒ B)(implicit bf: CanBuildFrom[Seq[A], B, That]): That
-
def
max: A
[use case] Finds the largest element.
[use case]Finds the largest element.
- returns
the largest element of this mutable sequence.
- Definition Classes
- TraversableOnce → GenTraversableOnce
- Exceptions thrown
UnsupportedOperationException
if this mutable sequence is empty.
Full Signaturedef max[B >: A](implicit cmp: Ordering[B]): A
-
def
maxBy[B](f: (A) ⇒ B): A
[use case] Finds the first element which yields the largest value measured by function f.
[use case]Finds the first element which yields the largest value measured by function f.
- B
The result type of the function f.
- f
The measuring function.
- returns
the first element of this mutable sequence with the largest value measured by function f.
- Definition Classes
- TraversableOnce → GenTraversableOnce
- Exceptions thrown
UnsupportedOperationException
if this mutable sequence is empty.
Full Signaturedef maxBy[B](f: (A) ⇒ B)(implicit cmp: Ordering[B]): A
-
def
min: A
[use case] Finds the smallest element.
[use case]Finds the smallest element.
- returns
the smallest element of this mutable sequence
- Definition Classes
- TraversableOnce → GenTraversableOnce
- Exceptions thrown
UnsupportedOperationException
if this mutable sequence is empty.
Full Signaturedef min[B >: A](implicit cmp: Ordering[B]): A
-
def
minBy[B](f: (A) ⇒ B): A
[use case] Finds the first element which yields the smallest value measured by function f.
[use case]Finds the first element which yields the smallest value measured by function f.
- B
The result type of the function f.
- f
The measuring function.
- returns
the first element of this mutable sequence with the smallest value measured by function f.
- Definition Classes
- TraversableOnce → GenTraversableOnce
- Exceptions thrown
UnsupportedOperationException
if this mutable sequence is empty.
Full Signaturedef minBy[B](f: (A) ⇒ B)(implicit cmp: Ordering[B]): A
-
def
mkString: String
Displays all elements of this traversable or iterator in a string.
Displays all elements of this traversable or iterator in a string.
- returns
a string representation of this traversable or iterator. In the resulting string the string representations (w.r.t. the method
toString
) of all elements of this traversable or iterator follow each other without any separator string.
- Definition Classes
- TraversableOnce → GenTraversableOnce
-
def
mkString(sep: String): String
Displays all elements of this traversable or iterator in a string using a separator string.
Displays all elements of this traversable or iterator in a string using a separator string.
- sep
the separator string.
- returns
a string representation of this traversable or iterator. In the resulting string the string representations (w.r.t. the method
toString
) of all elements of this traversable or iterator are separated by the stringsep
.
- Definition Classes
- TraversableOnce → GenTraversableOnce
List(1, 2, 3).mkString("|") = "1|2|3"
Example: -
def
mkString(start: String, sep: String, end: String): String
Displays all elements of this traversable or iterator in a string using start, end, and separator strings.
Displays all elements of this traversable or iterator in a string using start, end, and separator strings.
- start
the starting string.
- sep
the separator string.
- end
the ending string.
- returns
a string representation of this traversable or iterator. The resulting string begins with the string
start
and ends with the stringend
. Inside, the string representations (w.r.t. the methodtoString
) of all elements of this traversable or iterator are separated by the stringsep
.
- Definition Classes
- TraversableOnce → GenTraversableOnce
List(1, 2, 3).mkString("(", "; ", ")") = "(1; 2; 3)"
Example: -
final
def
ne(arg0: AnyRef): Boolean
Equivalent to
!(this eq that)
.Equivalent to
!(this eq that)
.- returns
true
if the argument is not a reference to the receiver object;false
otherwise.
- Definition Classes
- AnyRef
-
def
newBuilder: Builder[A, Seq[A]]
The builder that builds instances of type Traversable[A]
The builder that builds instances of type Traversable[A]
- Attributes
- protected[this]
- Definition Classes
- GenericTraversableTemplate → HasNewBuilder
-
def
nonEmpty: Boolean
Tests whether the traversable or iterator is not empty.
Tests whether the traversable or iterator is not empty.
- returns
true
if the traversable or iterator contains at least one element,false
otherwise.
- Definition Classes
- TraversableOnce → GenTraversableOnce
-
final
def
notify(): Unit
Wakes up a single thread that is waiting on the receiver object's monitor.
Wakes up a single thread that is waiting on the receiver object's monitor.
- Definition Classes
- AnyRef
- Annotations
- @native()
- Note
not specified by SLS as a member of AnyRef
-
final
def
notifyAll(): Unit
Wakes up all threads that are waiting on the receiver object's monitor.
Wakes up all threads that are waiting on the receiver object's monitor.
- Definition Classes
- AnyRef
- Annotations
- @native()
- Note
not specified by SLS as a member of AnyRef
-
def
orElse[A1 <: Int, B1 >: A](that: PartialFunction[A1, B1]): PartialFunction[A1, B1]
Composes this partial function with a fallback partial function which gets applied where this partial function is not defined.
Composes this partial function with a fallback partial function which gets applied where this partial function is not defined.
- A1
the argument type of the fallback function
- B1
the result type of the fallback function
- that
the fallback function
- returns
a partial function which has as domain the union of the domains of this partial function and
that
. The resulting partial function takesx
tothis(x)
wherethis
is defined, and tothat(x)
where it is not.
- Definition Classes
- PartialFunction
-
def
padTo(len: Int, elem: A): Seq[A]
[use case] A copy of this mutable sequence with an element value appended until a given target length is reached.
[use case]A copy of this mutable sequence with an element value appended until a given target length is reached.
- len
the target length
- elem
the padding value
- returns
a new mutable sequence consisting of all elements of this mutable sequence followed by the minimal number of occurrences of
elem
so that the resulting mutable sequence has a length of at leastlen
.
- Definition Classes
- SeqLike → GenSeqLike
Full Signaturedef padTo[B >: A, That](len: Int, elem: B)(implicit bf: CanBuildFrom[Seq[A], B, That]): That
-
def
par: ParSeq[A]
Returns a parallel implementation of this collection.
Returns a parallel implementation of this collection.
For most collection types, this method creates a new parallel collection by copying all the elements. For these collection,
par
takes linear time. Mutable collections in this category do not produce a mutable parallel collection that has the same underlying dataset, so changes in one collection will not be reflected in the other one.Specific collections (e.g.
ParArray
ormutable.ParHashMap
) override this default behaviour by creating a parallel collection which shares the same underlying dataset. For these collections,par
takes constant or sublinear time.All parallel collections return a reference to themselves.
- returns
a parallel implementation of this collection
- Definition Classes
- Parallelizable
-
def
parCombiner: Combiner[A, ParSeq[A]]
The default
par
implementation uses the combiner provided by this method to create a new parallel collection.The default
par
implementation uses the combiner provided by this method to create a new parallel collection.- returns
a combiner for the parallel collection of type
ParRepr
- Attributes
- protected[this]
- Definition Classes
- SeqLike → SeqLike → TraversableLike → Parallelizable
-
def
partition(p: (A) ⇒ Boolean): (Seq[A], Seq[A])
Partitions this traversable collection in two traversable collections according to a predicate.
Partitions this traversable collection in two traversable collections according to a predicate.
- p
the predicate on which to partition.
- returns
a pair of traversable collections: the first traversable collection consists of all elements that satisfy the predicate
p
and the second traversable collection consists of all elements that don't. The relative order of the elements in the resulting traversable collections is the same as in the original traversable collection.
- Definition Classes
- TraversableLike → GenTraversableLike
-
def
patch(from: Int, that: GenSeq[A], replaced: Int): Seq[A]
[use case] Produces a new mutable sequence where a slice of elements in this mutable sequence is replaced by another sequence.
[use case]Produces a new mutable sequence where a slice of elements in this mutable sequence is replaced by another sequence.
- from
the index of the first replaced element
- replaced
the number of elements to drop in the original mutable sequence
- returns
a new mutable sequence consisting of all elements of this mutable sequence except that
replaced
elements starting fromfrom
are replaced bypatch
.
- Definition Classes
- SeqLike → GenSeqLike
Full Signaturedef patch[B >: A, That](from: Int, patch: GenSeq[B], replaced: Int)(implicit bf: CanBuildFrom[Seq[A], B, That]): That
-
def
permutations: Iterator[Seq[A]]
Iterates over distinct permutations.
Iterates over distinct permutations.
- returns
An Iterator which traverses the distinct permutations of this sequence.
- Definition Classes
- SeqLike
"abb".permutations = Iterator(abb, bab, bba)
Example: -
def
prefixLength(p: (A) ⇒ Boolean): Int
Returns the length of the longest prefix whose elements all satisfy some predicate.
Returns the length of the longest prefix whose elements all satisfy some predicate.
Note: may not terminate for infinite-sized collections.
- p
the predicate used to test elements.
- returns
the length of the longest prefix of this general sequence such that every element of the segment satisfies the predicate
p
.
- Definition Classes
- GenSeqLike
-
def
product: A
[use case] Multiplies up the elements of this collection.
[use case]Multiplies up the elements of this collection.
- returns
the product of all elements in this mutable sequence of numbers of type
Int
. Instead ofInt
, any other typeT
with an implicitNumeric[T]
implementation can be used as element type of the mutable sequence and as result type ofproduct
. Examples of such types are:Long
,Float
,Double
,BigInt
.
- Definition Classes
- TraversableOnce → GenTraversableOnce
Full Signaturedef product[B >: A](implicit num: Numeric[B]): B
-
def
reduce[A1 >: A](op: (A1, A1) ⇒ A1): A1
Reduces the elements of this traversable or iterator using the specified associative binary operator.
Reduces the elements of this traversable or iterator using the specified associative binary operator.
The order in which operations are performed on elements is unspecified and may be nondeterministic.
- A1
A type parameter for the binary operator, a supertype of
A
.- op
A binary operator that must be associative.
- returns
The result of applying reduce operator
op
between all the elements if the traversable or iterator is nonempty.
- Definition Classes
- TraversableOnce → GenTraversableOnce
- Exceptions thrown
UnsupportedOperationException
if this traversable or iterator is empty.
-
def
reduceLeft[B >: A](op: (B, A) ⇒ B): B
Applies a binary operator to all elements of this traversable or iterator, going left to right.
Applies a binary operator to all elements of this traversable or iterator, going left to right.
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.
- B
the result type of the binary operator.
- op
the binary operator.
- returns
the result of inserting
op
between consecutive elements of this traversable or iterator, going left to right:op( op( ... op(x_1, x_2) ..., x_{n-1}), x_n)
where
x1, ..., xn
are the elements of this traversable or iterator.
- Definition Classes
- TraversableOnce
- Exceptions thrown
UnsupportedOperationException
if this traversable or iterator is empty.
-
def
reduceLeftOption[B >: A](op: (B, A) ⇒ B): Option[B]
Optionally applies a binary operator to all elements of this traversable or iterator, going left to right.
Optionally applies a binary operator to all elements of this traversable or iterator, going left to right.
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.
- B
the result type of the binary operator.
- op
the binary operator.
- returns
an option value containing the result of
reduceLeft(op)
if this traversable or iterator is nonempty,None
otherwise.
- Definition Classes
- TraversableOnce → GenTraversableOnce
-
def
reduceOption[A1 >: A](op: (A1, A1) ⇒ A1): Option[A1]
Reduces the elements of this traversable or iterator, if any, using the specified associative binary operator.
Reduces the elements of this traversable or iterator, if any, using the specified associative binary operator.
The order in which operations are performed on elements is unspecified and may be nondeterministic.
- A1
A type parameter for the binary operator, a supertype of
A
.- op
A binary operator that must be associative.
- returns
An option value containing result of applying reduce operator
op
between all the elements if the collection is nonempty, andNone
otherwise.
- Definition Classes
- TraversableOnce → GenTraversableOnce
-
def
reduceRight[B >: A](op: (A, B) ⇒ B): B
Applies a binary operator to all elements of this iterable collection, going right to left.
Applies a binary operator to all elements of this iterable collection, going right to left.
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered. or the operator is associative and commutative.
- B
the result type of the binary operator.
- op
the binary operator.
- returns
the result of inserting
op
between consecutive elements of this iterable collection, going right to left:op(x_1, op(x_2, ..., op(x_{n-1}, x_n)...))
where
x1, ..., xn
are the elements of this iterable collection.
- Definition Classes
- IterableLike → TraversableOnce → GenTraversableOnce
- Exceptions thrown
UnsupportedOperationException
if this iterable collection is empty.
-
def
reduceRightOption[B >: A](op: (A, B) ⇒ B): Option[B]
Optionally applies a binary operator to all elements of this traversable or iterator, going right to left.
Optionally applies a binary operator to all elements of this traversable or iterator, going right to left.
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.
- B
the result type of the binary operator.
- op
the binary operator.
- returns
an option value containing the result of
reduceRight(op)
if this traversable or iterator is nonempty,None
otherwise.
- Definition Classes
- TraversableOnce → GenTraversableOnce
-
def
repr: Seq[A]
The collection of type traversable collection underlying this
TraversableLike
object.The collection of type traversable collection underlying this
TraversableLike
object. By default this is implemented as theTraversableLike
object itself, but this can be overridden.- Definition Classes
- TraversableLike → GenTraversableLike
-
def
reverse: Seq[A]
Returns new sequence with elements in reversed order.
Returns new sequence with elements in reversed order.
Note: will not terminate for infinite-sized collections.
- returns
A new sequence with all elements of this sequence in reversed order.
- Definition Classes
- SeqLike → GenSeqLike
-
def
reverseIterator: Iterator[A]
An iterator yielding elements in reversed order.
An iterator yielding elements in reversed order.
Note: will not terminate for infinite-sized collections.
Note:
xs.reverseIterator
is the same asxs.reverse.iterator
but might be more efficient.- returns
an iterator yielding the elements of this sequence in reversed order
- Definition Classes
- SeqLike
-
def
reverseMap[B](f: (A) ⇒ B): Seq[B]
[use case] Builds a new collection by applying a function to all elements of this mutable sequence and collecting the results in reversed order.
[use case]Builds a new collection by applying a function to all elements of this mutable sequence and collecting the results in reversed order.
Note: will not terminate for infinite-sized collections.
Note:
xs.reverseMap(f)
is the same asxs.reverse.map(f)
but might be more efficient.- B
the element type of the returned collection.
- f
the function to apply to each element.
- returns
a new mutable sequence resulting from applying the given function
f
to each element of this mutable sequence and collecting the results in reversed order.
- Definition Classes
- SeqLike → GenSeqLike
Full Signaturedef reverseMap[B, That](f: (A) ⇒ B)(implicit bf: CanBuildFrom[Seq[A], B, That]): That
-
def
reversed: List[A]
- Attributes
- protected[this]
- Definition Classes
- TraversableOnce
-
def
runWith[U](action: (A) ⇒ U): (Int) ⇒ Boolean
Composes this partial function with an action function which gets applied to results of this partial function.
Composes this partial function with an action function which gets applied to results of this partial function. The action function is invoked only for its side effects; its result is ignored.
Note that expression
pf.runWith(action)(x)
is equivalent toif(pf isDefinedAt x) { action(pf(x)); true } else false
except that
runWith
is implemented viaapplyOrElse
and thus potentially more efficient. UsingrunWith
avoids double evaluation of pattern matchers and guards for partial function literals.- action
the action function
- returns
a function which maps arguments
x
toisDefinedAt(x)
. The resulting function runsaction(this(x))
wherethis
is defined.
- Definition Classes
- PartialFunction
- Since
2.10
- See also
applyOrElse
.
-
def
sameElements(that: GenIterable[A]): Boolean
[use case] Checks if the other iterable collection contains the same elements in the same order as this mutable sequence.
[use case]Checks if the other iterable collection contains the same elements in the same order as this mutable sequence.
Note: will not terminate for infinite-sized collections.
- that
the collection to compare with.
- returns
true
, if both collections contain the same elements in the same order,false
otherwise.
- Definition Classes
- IterableLike → GenIterableLike
Full Signaturedef sameElements[B >: A](that: GenIterable[B]): Boolean
-
def
scan[B >: A, That](z: B)(op: (B, B) ⇒ B)(implicit cbf: CanBuildFrom[Seq[A], B, That]): That
Computes a prefix scan of the elements of the collection.
Computes a prefix scan of the elements of the collection.
Note: The neutral element
z
may be applied more than once.- B
element type of the resulting collection
- That
type of the resulting collection
- z
neutral element for the operator
op
- op
the associative operator for the scan
- cbf
combiner factory which provides a combiner
- returns
a new traversable collection containing the prefix scan of the elements in this traversable collection
- Definition Classes
- TraversableLike → GenTraversableLike
-
def
scanLeft[B, That](z: B)(op: (B, A) ⇒ B)(implicit bf: CanBuildFrom[Seq[A], B, That]): That
Produces a collection containing cumulative results of applying the operator going left to right.
Produces a collection containing cumulative results of applying the operator going left to right.
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- B
the type of the elements in the resulting collection
- That
the actual type of the resulting collection
- z
the initial value
- op
the binary operator applied to the intermediate result and the element
- bf
an implicit value of class
CanBuildFrom
which determines the result classThat
from the current representation typeRepr
and the new element typeB
.- returns
collection with intermediate results
- Definition Classes
- TraversableLike → GenTraversableLike
-
def
scanRight[B, That](z: B)(op: (A, B) ⇒ B)(implicit bf: CanBuildFrom[Seq[A], B, That]): That
Produces a collection containing cumulative results of applying the operator going right to left.
Produces a collection containing cumulative results of applying the operator going right to left. The head of the collection is the last cumulative result.
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered.
Example:
List(1, 2, 3, 4).scanRight(0)(_ + _) == List(10, 9, 7, 4, 0)
- B
the type of the elements in the resulting collection
- That
the actual type of the resulting collection
- z
the initial value
- op
the binary operator applied to the intermediate result and the element
- bf
an implicit value of class
CanBuildFrom
which determines the result classThat
from the current representation typeRepr
and the new element typeB
.- returns
collection with intermediate results
- Definition Classes
- TraversableLike → GenTraversableLike
- Annotations
- @migration
- Migration
(Changed in version 2.9.0) The behavior of
scanRight
has changed. The previous behavior can be reproduced with scanRight.reverse.
-
def
segmentLength(p: (A) ⇒ Boolean, from: Int): Int
Computes length of longest segment whose elements all satisfy some predicate.
Computes length of longest segment whose elements all satisfy some predicate.
Note: may not terminate for infinite-sized collections.
- p
the predicate used to test elements.
- from
the index where the search starts.
- returns
the length of the longest segment of this sequence starting from index
from
such that every element of the segment satisfies the predicatep
.
- Definition Classes
- SeqLike → GenSeqLike
-
def
seq: Seq[A]
A version of this collection with all of the operations implemented sequentially (i.e., in a single-threaded manner).
A version of this collection with all of the operations implemented sequentially (i.e., in a single-threaded manner).
This method returns a reference to this collection. In parallel collections, it is redefined to return a sequential implementation of this collection. In both cases, it has O(1) complexity.
- returns
a sequential view of the collection.
- Definition Classes
- Seq → Seq → GenSeq → GenSeqLike → Iterable → Iterable → GenIterable → Traversable → Traversable → GenTraversable → Parallelizable → TraversableOnce → GenTraversableOnce
-
def
size: Int
The size of this sequence, equivalent to
length
.The size of this sequence, equivalent to
length
.Note: will not terminate for infinite-sized collections.
- returns
the number of elements in this sequence.
- Definition Classes
- SeqLike → GenTraversableLike → TraversableOnce → GenTraversableOnce
-
def
sizeHintIfCheap: Int
The size of this collection or iterator, if it can be cheaply computed
The size of this collection or iterator, if it can be cheaply computed
- returns
the number of elements in this collection or iterator, or -1 if the size cannot be determined cheaply
- Attributes
- protected[collection]
- Definition Classes
- GenTraversableOnce
-
def
slice(from: Int, until: Int): Seq[A]
Selects an interval of elements.
Selects an interval of elements. The returned collection is made up of all elements
x
which satisfy the invariant:from <= indexOf(x) < until
Note: might return different results for different runs, unless the underlying collection type is ordered.
- returns
a iterable collection containing the elements greater than or equal to index
from
extending up to (but not including) indexuntil
of this iterable collection.
- Definition Classes
- IterableLike → TraversableLike → GenTraversableLike
-
def
sliding(size: Int, step: Int): Iterator[Seq[A]]
Groups elements in fixed size blocks by passing a "sliding window" over them (as opposed to partitioning them, as is done in grouped.)
Groups elements in fixed size blocks by passing a "sliding window" over them (as opposed to partitioning them, as is done in grouped.)
- size
the number of elements per group
- step
the distance between the first elements of successive groups
- returns
An iterator producing iterable collections of size
size
, except the last element (which may be the only element) will be truncated if there are fewer thansize
elements remaining to be grouped.
- Definition Classes
- IterableLike
- See also
scala.collection.Iterator, method
sliding
-
def
sliding(size: Int): Iterator[Seq[A]]
Groups elements in fixed size blocks by passing a "sliding window" over them (as opposed to partitioning them, as is done in
grouped
.) The "sliding window" step is set to one.Groups elements in fixed size blocks by passing a "sliding window" over them (as opposed to partitioning them, as is done in
grouped
.) The "sliding window" step is set to one.- size
the number of elements per group
- returns
An iterator producing iterable collections of size
size
, except the last element (which may be the only element) will be truncated if there are fewer thansize
elements remaining to be grouped.
- Definition Classes
- IterableLike
- See also
scala.collection.Iterator, method
sliding
-
def
sortBy[B](f: (A) ⇒ B)(implicit ord: math.Ordering[B]): Seq[A]
Sorts this
Seq
according to the Ordering which results from transforming an implicitly given Ordering with a transformation function.Sorts this
Seq
according to the Ordering which results from transforming an implicitly given Ordering with a transformation function.- B
the target type of the transformation
f
, and the type where the orderingord
is defined.- f
the transformation function mapping elements to some other domain
B
.- ord
the ordering assumed on domain
B
.- returns
a sequence consisting of the elements of this sequence sorted according to the ordering where
x < y
iford.lt(f(x), f(y))
.
- Definition Classes
- SeqLike
val words = "The quick brown fox jumped over the lazy dog".split(' ') // this works because scala.Ordering will implicitly provide an Ordering[Tuple2[Int, Char]] words.sortBy(x => (x.length, x.head)) res0: Array[String] = Array(The, dog, fox, the, lazy, over, brown, quick, jumped)
- See also
scala.math.Ordering Note: will not terminate for infinite-sized collections.
Example: -
def
sortWith(lt: (A, A) ⇒ Boolean): Seq[A]
Sorts this sequence according to a comparison function.
Sorts this sequence according to a comparison function.
Note: will not terminate for infinite-sized collections.
The sort is stable. That is, elements that are equal (as determined by
lt
) appear in the same order in the sorted sequence as in the original.- lt
the comparison function which tests whether its first argument precedes its second argument in the desired ordering.
- returns
a sequence consisting of the elements of this sequence sorted according to the comparison function
lt
.
- Definition Classes
- SeqLike
List("Steve", "Tom", "John", "Bob").sortWith(_.compareTo(_) < 0) = List("Bob", "John", "Steve", "Tom")
Example: -
def
sorted[B >: A](implicit ord: math.Ordering[B]): Seq[A]
Sorts this sequence according to an Ordering.
Sorts this sequence according to an Ordering.
The sort is stable. That is, elements that are equal (as determined by
lt
) appear in the same order in the sorted sequence as in the original.- ord
the ordering to be used to compare elements.
- returns
a sequence consisting of the elements of this sequence sorted according to the ordering
ord
.
- Definition Classes
- SeqLike
- See also
-
def
span(p: (A) ⇒ Boolean): (Seq[A], Seq[A])
Splits this traversable collection into a prefix/suffix pair according to a predicate.
Splits this traversable collection into a prefix/suffix pair according to a predicate.
Note:
c span p
is equivalent to (but possibly more efficient than)(c takeWhile p, c dropWhile p)
, provided the evaluation of the predicatep
does not cause any side-effects.Note: might return different results for different runs, unless the underlying collection type is ordered.
- returns
a pair consisting of the longest prefix of this traversable collection whose elements all satisfy
p
, and the rest of this traversable collection.
- Definition Classes
- TraversableLike → GenTraversableLike
-
def
splitAt(n: Int): (Seq[A], Seq[A])
Splits this traversable collection into two at a given position.
Splits this traversable collection into two at a given position. Note:
c splitAt n
is equivalent to (but possibly more efficient than)(c take n, c drop n)
.Note: might return different results for different runs, unless the underlying collection type is ordered.
- n
the position at which to split.
- returns
a pair of traversable collections consisting of the first
n
elements of this traversable collection, and the other elements.
- Definition Classes
- TraversableLike → GenTraversableLike
-
def
startsWith[B](that: GenSeq[B], offset: Int): Boolean
Tests whether this sequence contains the given sequence at a given index.
Tests whether this sequence contains the given sequence at a given index.
Note: If the both the receiver object
this
and the argumentthat
are infinite sequences this method may not terminate.- that
the sequence to test
- offset
the index where the sequence is searched.
- returns
true
if the sequencethat
is contained in this sequence at indexoffset
, otherwisefalse
.
- Definition Classes
- SeqLike → GenSeqLike
-
def
startsWith[B](that: GenSeq[B]): Boolean
Tests whether this general sequence starts with the given sequence.
Tests whether this general sequence starts with the given sequence.
- that
the sequence to test
- returns
true
if this collection hasthat
as a prefix,false
otherwise.
- Definition Classes
- GenSeqLike
-
def
stringPrefix: String
Defines the prefix of this object's
toString
representation.Defines the prefix of this object's
toString
representation.- returns
a string representation which starts the result of
toString
applied to this traversable collection. By default the string prefix is the simple name of the collection class traversable collection.
- Definition Classes
- TraversableLike → GenTraversableLike
-
def
sum: A
[use case] Sums up the elements of this collection.
[use case]Sums up the elements of this collection.
- returns
the sum of all elements in this mutable sequence of numbers of type
Int
. Instead ofInt
, any other typeT
with an implicitNumeric[T]
implementation can be used as element type of the mutable sequence and as result type ofsum
. Examples of such types are:Long
,Float
,Double
,BigInt
.
- Definition Classes
- TraversableOnce → GenTraversableOnce
Full Signaturedef sum[B >: A](implicit num: Numeric[B]): B
-
final
def
synchronized[T0](arg0: ⇒ T0): T0
- Definition Classes
- AnyRef
-
def
tail: Seq[A]
Selects all elements except the first.
Selects all elements except the first.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- returns
a traversable collection consisting of all elements of this traversable collection except the first one.
- Definition Classes
- TraversableLike → GenTraversableLike
- Exceptions thrown
java.lang.UnsupportedOperationException
if the traversable collection is empty.
-
def
tails: Iterator[Seq[A]]
Iterates over the tails of this traversable collection.
Iterates over the tails of this traversable collection. The first value will be this traversable collection and the final one will be an empty traversable collection, with the intervening values the results of successive applications of
tail
.- returns
an iterator over all the tails of this traversable collection
- Definition Classes
- TraversableLike
List(1,2,3).tails = Iterator(List(1,2,3), List(2,3), List(3), Nil)
Example: -
def
take(n: Int): Seq[A]
Selects first n elements.
Selects first n elements.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- n
the number of elements to take from this iterable collection.
- returns
a iterable collection consisting only of the first
n
elements of this iterable collection, or else the whole iterable collection, if it has less thann
elements. Ifn
is negative, returns an empty iterable collection.
- Definition Classes
- IterableLike → TraversableLike → GenTraversableLike
-
def
takeRight(n: Int): Seq[A]
Selects last n elements.
Selects last n elements.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- n
the number of elements to take
- returns
a iterable collection consisting only of the last
n
elements of this iterable collection, or else the whole iterable collection, if it has less thann
elements.
- Definition Classes
- IterableLike
-
def
takeWhile(p: (A) ⇒ Boolean): Seq[A]
Takes longest prefix of elements that satisfy a predicate.
Takes longest prefix of elements that satisfy a predicate.
Note: might return different results for different runs, unless the underlying collection type is ordered.
- returns
the longest prefix of this iterable collection whose elements all satisfy the predicate
p
.
- Definition Classes
- IterableLike → TraversableLike → GenTraversableLike
-
def
thisCollection: collection.Seq[A]
The underlying collection seen as an instance of
.Seq
The underlying collection seen as an instance of
. By default this is implemented as the current collection object itself, but this can be overridden.Seq
- Attributes
- protected[this]
- Definition Classes
- SeqLike → IterableLike → TraversableLike
-
def
to[Col[_]]: Col[A]
[use case] Converts this mutable sequence into another by copying all elements.
[use case]Converts this mutable sequence into another by copying all elements.
Note: will not terminate for infinite-sized collections.
- Col
The collection type to build.
- returns
a new collection containing all elements of this mutable sequence.
- Definition Classes
- TraversableLike → TraversableOnce → GenTraversableOnce
Full Signaturedef to[Col[_]](implicit cbf: CanBuildFrom[Nothing, A, Col[A]]): Col[A]
-
def
toArray: Array[A]
[use case] Converts this mutable sequence to an array.
[use case]Converts this mutable sequence to an array.
Note: will not terminate for infinite-sized collections.
- returns
an array containing all elements of this mutable sequence. An
ClassTag
must be available for the element type of this mutable sequence.
- Definition Classes
- TraversableOnce → GenTraversableOnce
-
def
toBuffer[B >: A]: Buffer[B]
Uses the contents of this traversable or iterator to create a new mutable buffer.
Uses the contents of this traversable or iterator to create a new mutable buffer.
Note: will not terminate for infinite-sized collections.
- returns
a buffer containing all elements of this traversable or iterator.
- Definition Classes
- TraversableOnce → GenTraversableOnce
-
def
toCollection(repr: Seq[A]): collection.Seq[A]
A conversion from collections of type
Repr
to
objects.Seq
A conversion from collections of type
Repr
to
objects. By default this is implemented as just a cast, but this can be overridden.Seq
- Attributes
- protected[this]
- Definition Classes
- SeqLike → IterableLike → TraversableLike
-
def
toIndexedSeq: immutable.IndexedSeq[A]
Converts this traversable or iterator to an indexed sequence.
Converts this traversable or iterator to an indexed sequence.
Note: will not terminate for infinite-sized collections.
- returns
an indexed sequence containing all elements of this traversable or iterator.
- Definition Classes
- TraversableOnce → GenTraversableOnce
-
def
toIterable: collection.Iterable[A]
Returns this iterable collection as an iterable collection.
Returns this iterable collection as an iterable collection.
A new collection will not be built; lazy collections will stay lazy.
Note: will not terminate for infinite-sized collections.
- returns
an
Iterable
containing all elements of this iterable collection.
- Definition Classes
- IterableLike → TraversableOnce → GenTraversableOnce
-
def
toIterator: Iterator[A]
Returns an Iterator over the elements in this iterable collection.
Returns an Iterator over the elements in this iterable collection. Produces the same result as
iterator
.Note: will not terminate for infinite-sized collections.
- returns
an Iterator containing all elements of this iterable collection.
- Definition Classes
- IterableLike → TraversableLike → GenTraversableOnce
- Annotations
- @deprecatedOverriding( message = ... , since = "2.11.0" )
-
def
toList: List[A]
Converts this traversable or iterator to a list.
Converts this traversable or iterator to a list.
Note: will not terminate for infinite-sized collections.
- returns
a list containing all elements of this traversable or iterator.
- Definition Classes
- TraversableOnce → GenTraversableOnce
-
def
toMap[T, U]: collection.Map[T, U]
[use case] Converts this mutable sequence to a map.
[use case]Converts this mutable sequence to a map. This method is unavailable unless the elements are members of Tuple2, each ((T, U)) becoming a key-value pair in the map. Duplicate keys will be overwritten by later keys: if this is an unordered collection, which key is in the resulting map is undefined.
Note: will not terminate for infinite-sized collections.
- returns
a map of type
immutable.Map[T, U]
containing all key/value pairs of type(T, U)
of this mutable sequence.
- Definition Classes
- TraversableOnce → GenTraversableOnce
Full Signaturedef toMap[T, U](implicit ev: <:<[A, (T, U)]): immutable.Map[T, U]
-
def
toParArray: ParArray[T]
- Implicit
- This member is added by an implicit conversion from Seq[A] to CollectionsHaveToParArray[Seq[A], T] performed by method CollectionsHaveToParArray in scala.collection.parallel. This conversion will take place only if an implicit value of type (Seq[A]) ⇒ GenTraversableOnce[T] is in scope.
- Definition Classes
- CollectionsHaveToParArray
-
def
toSeq: collection.Seq[A]
Converts this sequence to a sequence.
Converts this sequence to a sequence.
Note: will not terminate for infinite-sized collections.
A new collection will not be built; in particular, lazy sequences will stay lazy.
- returns
a sequence containing all elements of this sequence.
- Definition Classes
- SeqLike → GenSeqLike → TraversableOnce → GenTraversableOnce
-
def
toSet[B >: A]: immutable.Set[B]
Converts this traversable or iterator to a set.
Converts this traversable or iterator to a set.
Note: will not terminate for infinite-sized collections.
- returns
a set containing all elements of this traversable or iterator.
- Definition Classes
- TraversableOnce → GenTraversableOnce
-
def
toStream: immutable.Stream[A]
Converts this iterable collection to a stream.
Converts this iterable collection to a stream.
- returns
a stream containing all elements of this iterable collection.
- Definition Classes
- IterableLike → TraversableLike → GenTraversableOnce
-
def
toString(): String
Converts this sequence to a string.
Converts this sequence to a string.
- returns
a string representation of this collection. By default this string consists of the
stringPrefix
of this sequence, followed by all elements separated by commas and enclosed in parentheses.
- Definition Classes
- SeqLike → TraversableLike → Any
-
def
toTraversable: collection.Traversable[A]
Converts this traversable collection to an unspecified Traversable.
Converts this traversable collection to an unspecified Traversable. Will return the same collection if this instance is already Traversable.
Note: will not terminate for infinite-sized collections.
- returns
a Traversable containing all elements of this traversable collection.
- Definition Classes
- TraversableLike → TraversableOnce → GenTraversableOnce
- Annotations
- @deprecatedOverriding( message = ... , since = "2.11.0" )
-
def
toVector: Vector[A]
Converts this traversable or iterator to a Vector.
Converts this traversable or iterator to a Vector.
Note: will not terminate for infinite-sized collections.
- returns
a vector containing all elements of this traversable or iterator.
- Definition Classes
- TraversableOnce → GenTraversableOnce
-
def
transform(f: (A) ⇒ A): Seq.this.type
Applies a transformation function to all values contained in this sequence.
Applies a transformation function to all values contained in this sequence. The transformation function produces new values from existing elements.
- f
the transformation to apply
- returns
the sequence itself.
- Definition Classes
- SeqLike
-
def
transpose[B](implicit asTraversable: (A) ⇒ GenTraversableOnce[B]): Seq[Seq[B]]
Transposes this collection of traversable collections into a collection of collections.
Transposes this collection of traversable collections into a collection of collections.
The resulting collection's type will be guided by the static type of collection. For example:
val xs = List( Set(1, 2, 3), Set(4, 5, 6)).transpose // xs == List( // List(1, 4), // List(2, 5), // List(3, 6)) val ys = Vector( List(1, 2, 3), List(4, 5, 6)).transpose // ys == Vector( // Vector(1, 4), // Vector(2, 5), // Vector(3, 6))
- B
the type of the elements of each traversable collection.
- asTraversable
an implicit conversion which asserts that the element type of this collection is a
Traversable
.- returns
a two-dimensional collection of collections which has as nth row the nth column of this collection.
- Definition Classes
- GenericTraversableTemplate
- Annotations
- @migration
- Migration
(Changed in version 2.9.0)
transpose
throws anIllegalArgumentException
if collections are not uniformly sized.- Exceptions thrown
IllegalArgumentException
if all collections in this collection are not of the same size.
-
def
union(that: collection.Seq[A]): Seq[A]
[use case] Produces a new sequence which contains all elements of this mutable sequence and also all elements of a given sequence.
[use case]Produces a new sequence which contains all elements of this mutable sequence and also all elements of a given sequence.
xs union ys
is equivalent toxs ++ ys
.Another way to express this is that
xs union ys
computes the order-preserving multi-set union ofxs
andys
.union
is hence a counter-part ofdiff
andintersect
which also work on multi-sets.Note: will not terminate for infinite-sized collections.
- that
the sequence to add.
- returns
a new mutable sequence which contains all elements of this mutable sequence followed by all elements of
that
.
- Definition Classes
- SeqLike → GenSeqLike
Full Signaturedef union[B >: A, That](that: GenSeq[B])(implicit bf: CanBuildFrom[Seq[A], B, That]): That
-
def
unzip[A1, A2](implicit asPair: (A) ⇒ (A1, A2)): (Seq[A1], Seq[A2])
Converts this collection of pairs into two collections of the first and second half of each pair.
Converts this collection of pairs into two collections of the first and second half of each pair.
val xs = Traversable( (1, "one"), (2, "two"), (3, "three")).unzip // xs == (Traversable(1, 2, 3), // Traversable(one, two, three))
- A1
the type of the first half of the element pairs
- A2
the type of the second half of the element pairs
- asPair
an implicit conversion which asserts that the element type of this collection is a pair.
- returns
a pair of collections, containing the first, respectively second half of each element pair of this collection.
- Definition Classes
- GenericTraversableTemplate
-
def
unzip3[A1, A2, A3](implicit asTriple: (A) ⇒ (A1, A2, A3)): (Seq[A1], Seq[A2], Seq[A3])
Converts this collection of triples into three collections of the first, second, and third element of each triple.
Converts this collection of triples into three collections of the first, second, and third element of each triple.
val xs = Traversable( (1, "one", '1'), (2, "two", '2'), (3, "three", '3')).unzip3 // xs == (Traversable(1, 2, 3), // Traversable(one, two, three), // Traversable(1, 2, 3))
- A1
the type of the first member of the element triples
- A2
the type of the second member of the element triples
- A3
the type of the third member of the element triples
- asTriple
an implicit conversion which asserts that the element type of this collection is a triple.
- returns
a triple of collections, containing the first, second, respectively third member of each element triple of this collection.
- Definition Classes
- GenericTraversableTemplate
-
def
updated(index: Int, elem: A): Seq[A]
[use case] A copy of this mutable sequence with one single replaced element.
[use case]A copy of this mutable sequence with one single replaced element.
- index
the position of the replacement
- elem
the replacing element
- returns
a copy of this mutable sequence with the element at position
index
replaced byelem
.
- Definition Classes
- SeqLike → GenSeqLike
Full Signaturedef updated[B >: A, That](index: Int, elem: B)(implicit bf: CanBuildFrom[Seq[A], B, That]): That
-
def
view(from: Int, until: Int): SeqView[A, Seq[A]]
Creates a non-strict view of a slice of this sequence.
Creates a non-strict view of a slice of this sequence.
Note: the difference between
view
andslice
is thatview
produces a view of the current sequence, whereasslice
produces a new sequence.Note:
view(from, to)
is equivalent toview.slice(from, to)
- from
the index of the first element of the view
- until
the index of the element following the view
- returns
a non-strict view of a slice of this sequence, starting at index
from
and extending up to (but not including) indexuntil
.
- Definition Classes
- SeqLike → IterableLike → TraversableLike
-
def
view: SeqView[A, Seq[A]]
Creates a non-strict view of this sequence.
Creates a non-strict view of this sequence.
- returns
a non-strict view of this sequence.
- Definition Classes
- SeqLike → IterableLike → TraversableLike
-
final
def
wait(): Unit
- Definition Classes
- AnyRef
- Annotations
- @throws( ... )
-
final
def
wait(arg0: Long, arg1: Int): Unit
- Definition Classes
- AnyRef
- Annotations
- @throws( ... )
- final def wait(arg0: Long): Unit
-
def
withFilter(p: (A) ⇒ Boolean): FilterMonadic[A, Seq[A]]
Creates a non-strict filter of this traversable collection.
Creates a non-strict filter of this traversable collection.
Note: the difference between
c filter p
andc withFilter p
is that the former creates a new collection, whereas the latter only restricts the domain of subsequentmap
,flatMap
,foreach
, andwithFilter
operations.Note: might return different results for different runs, unless the underlying collection type is ordered.
- p
the predicate used to test elements.
- returns
an object of class
WithFilter
, which supportsmap
,flatMap
,foreach
, andwithFilter
operations. All these operations apply to those elements of this traversable collection which satisfy the predicatep
.
- Definition Classes
- TraversableLike → FilterMonadic
-
def
zip[B](that: GenIterable[B]): Seq[(A, B)]
[use case] Returns a mutable sequence formed from this mutable sequence and another iterable collection by combining corresponding elements in pairs.
[use case]Returns a mutable sequence formed from this mutable sequence and another iterable collection by combining corresponding elements in pairs. If one of the two collections is longer than the other, its remaining elements are ignored.
- B
the type of the second half of the returned pairs
- that
The iterable providing the second half of each result pair
- returns
a new mutable sequence containing pairs consisting of corresponding elements of this mutable sequence and
that
. The length of the returned collection is the minimum of the lengths of this mutable sequence andthat
.
- Definition Classes
- IterableLike → GenIterableLike
Full Signaturedef zip[A1 >: A, B, That](that: GenIterable[B])(implicit bf: CanBuildFrom[Seq[A], (A1, B), That]): That
-
def
zipAll[B](that: collection.Iterable[B], thisElem: A, thatElem: B): Seq[(A, B)]
[use case] Returns a mutable sequence formed from this mutable sequence and another iterable collection by combining corresponding elements in pairs.
[use case]Returns a mutable sequence formed from this mutable sequence and another iterable collection by combining corresponding elements in pairs. If one of the two collections is shorter than the other, placeholder elements are used to extend the shorter collection to the length of the longer.
- B
the type of the second half of the returned pairs
- that
The iterable providing the second half of each result pair
- thisElem
the element to be used to fill up the result if this mutable sequence is shorter than
that
.- thatElem
the element to be used to fill up the result if
that
is shorter than this mutable sequence.- returns
a new mutable sequence containing pairs consisting of corresponding elements of this mutable sequence and
that
. The length of the returned collection is the maximum of the lengths of this mutable sequence andthat
. If this mutable sequence is shorter thanthat
,thisElem
values are used to pad the result. Ifthat
is shorter than this mutable sequence,thatElem
values are used to pad the result.
- Definition Classes
- IterableLike → GenIterableLike
Full Signaturedef zipAll[B, A1 >: A, That](that: GenIterable[B], thisElem: A1, thatElem: B)(implicit bf: CanBuildFrom[Seq[A], (A1, B), That]): That
-
def
zipWithIndex: Seq[(A, Int)]
[use case] Zips this mutable sequence with its indices.
[use case]Zips this mutable sequence with its indices.
- returns
A new mutable sequence containing pairs consisting of all elements of this mutable sequence paired with their index. Indices start at
0
.
- Definition Classes
- IterableLike → GenIterableLike
List("a", "b", "c").zipWithIndex = List(("a", 0), ("b", 1), ("c", 2))
Full Signaturedef zipWithIndex[A1 >: A, That](implicit bf: CanBuildFrom[Seq[A], (A1, Int), That]): That
Example: -
def
→[B](y: B): (Seq[A], B)
- Implicit
- This member is added by an implicit conversion from Seq[A] to ArrowAssoc[Seq[A]] performed by method ArrowAssoc in scala.Predef.
- Definition Classes
- ArrowAssoc
Shadowed Implicit Value Members
-
def
filter(p: (A) ⇒ Boolean): TraversableOnce[A]
- Implicit
- This member is added by an implicit conversion from Seq[A] to MonadOps[A] performed by method MonadOps in scala.collection.TraversableOnce.
- Shadowing
- This implicitly inherited member is shadowed by one or more members in this class.
To access this member you can use a type ascription:(seq: MonadOps[A]).filter(p)
- Definition Classes
- MonadOps
-
def
flatMap[B](f: (A) ⇒ GenTraversableOnce[B]): TraversableOnce[B]
- Implicit
- This member is added by an implicit conversion from Seq[A] to MonadOps[A] performed by method MonadOps in scala.collection.TraversableOnce.
- Shadowing
- This implicitly inherited member is shadowed by one or more members in this class.
To access this member you can use a type ascription:(seq: MonadOps[A]).flatMap(f)
- Definition Classes
- MonadOps
-
def
map[B](f: (A) ⇒ B): TraversableOnce[B]
- Implicit
- This member is added by an implicit conversion from Seq[A] to MonadOps[A] performed by method MonadOps in scala.collection.TraversableOnce.
- Shadowing
- This implicitly inherited member is shadowed by one or more members in this class.
To access this member you can use a type ascription:(seq: MonadOps[A]).map(f)
- Definition Classes
- MonadOps
-
def
withFilter(p: (A) ⇒ Boolean): Iterator[A]
- Implicit
- This member is added by an implicit conversion from Seq[A] to MonadOps[A] performed by method MonadOps in scala.collection.TraversableOnce.
- Shadowing
- This implicitly inherited member is shadowed by one or more members in this class.
To access this member you can use a type ascription:(seq: MonadOps[A]).withFilter(p)
- Definition Classes
- MonadOps
Deprecated Value Members
-
def
/:[B](z: B)(op: (B, A) ⇒ B): B
Applies a binary operator to a start value and all elements of this traversable or iterator, going left to right.
Applies a binary operator to a start value and all elements of this traversable or iterator, going left to right.
Note:
/:
is alternate syntax forfoldLeft
;z /: xs
is the same asxs foldLeft z
.Examples:
Note that the folding function used to compute b is equivalent to that used to compute c.
scala> val a = List(1,2,3,4) a: List[Int] = List(1, 2, 3, 4) scala> val b = (5 /: a)(_+_) b: Int = 15 scala> val c = (5 /: a)((x,y) => x + y) c: Int = 15
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.
- B
the result type of the binary operator.
- z
the start value.
- op
the binary operator.
- returns
the result of inserting
op
between consecutive elements of this traversable or iterator, going left to right with the start valuez
on the left:op(...op(op(z, x_1), x_2), ..., x_n)
where
x1, ..., xn
are the elements of this traversable or iterator.
- Definition Classes
- TraversableOnce → GenTraversableOnce
- Annotations
- @deprecated
- Deprecated
(Since version 2.12.10) Use foldLeft instead of /:
-
def
:\[B](z: B)(op: (A, B) ⇒ B): B
Applies a binary operator to all elements of this traversable or iterator and a start value, going right to left.
Applies a binary operator to all elements of this traversable or iterator and a start value, going right to left.
Note:
:\
is alternate syntax forfoldRight
;xs :\ z
is the same asxs foldRight z
.Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.
Examples:
Note that the folding function used to compute b is equivalent to that used to compute c.
scala> val a = List(1,2,3,4) a: List[Int] = List(1, 2, 3, 4) scala> val b = (a :\ 5)(_+_) b: Int = 15 scala> val c = (a :\ 5)((x,y) => x + y) c: Int = 15
- B
the result type of the binary operator.
- z
the start value
- op
the binary operator
- returns
the result of inserting
op
between consecutive elements of this traversable or iterator, going right to left with the start valuez
on the right:op(x_1, op(x_2, ... op(x_n, z)...))
where
x1, ..., xn
are the elements of this traversable or iterator.
- Definition Classes
- TraversableOnce → GenTraversableOnce
- Annotations
- @deprecated
- Deprecated
(Since version 2.12.10) Use foldRight instead of :\
This is the documentation for the Scala standard library.
Package structure
The scala package contains core types like
Int
,Float
,Array
orOption
which are accessible in all Scala compilation units without explicit qualification or imports.Notable packages include:
scala.collection
and its sub-packages contain Scala's collections frameworkscala.collection.immutable
- Immutable, sequential data-structures such asVector
,List
,Range
,HashMap
orHashSet
scala.collection.mutable
- Mutable, sequential data-structures such asArrayBuffer
,StringBuilder
,HashMap
orHashSet
scala.collection.concurrent
- Mutable, concurrent data-structures such asTrieMap
scala.collection.parallel.immutable
- Immutable, parallel data-structures such asParVector
,ParRange
,ParHashMap
orParHashSet
scala.collection.parallel.mutable
- Mutable, parallel data-structures such asParArray
,ParHashMap
,ParTrieMap
orParHashSet
scala.concurrent
- Primitives for concurrent programming such asFutures
andPromises
scala.io
- Input and output operationsscala.math
- Basic math functions and additional numeric types likeBigInt
andBigDecimal
scala.sys
- Interaction with other processes and the operating systemscala.util.matching
- Regular expressionsOther packages exist. See the complete list on the right.
Additional parts of the standard library are shipped as separate libraries. These include:
scala.reflect
- Scala's reflection API (scala-reflect.jar)scala.xml
- XML parsing, manipulation, and serialization (scala-xml.jar)scala.swing
- A convenient wrapper around Java's GUI framework called Swing (scala-swing.jar)scala.util.parsing
- Parser combinators (scala-parser-combinators.jar)Automatic imports
Identifiers in the scala package and the
scala.Predef
object are always in scope by default.Some of these identifiers are type aliases provided as shortcuts to commonly used classes. For example,
List
is an alias forscala.collection.immutable.List
.Other aliases refer to classes provided by the underlying platform. For example, on the JVM,
String
is an alias forjava.lang.String
.