Applies a binary operator to a start value and all elements of this collection or iterator, going left to right.
Applies a binary operator to a start value and all elements of this collection or iterator, going left to right.
Note: /:
is alternate syntax for foldLeft
; z /: xs
is the same as
xs 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.
the result type of the binary operator.
the start value.
the binary operator.
the result of inserting op
between consecutive elements of this collection or iterator,
going left to right with the start value z
on the left:
op(...op(op(z, x_1), x_2), ..., x_n)
where x_{1}, ..., x_{n}
are the elements of this collection or iterator.
Applies a binary operator to all elements of this collection or iterator and a start value, going right to left.
Applies a binary operator to all elements of this collection or iterator and a start value, going right to left.
Note: :\
is alternate syntax for foldRight
; xs :\ z
is the same as
xs 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
the result type of the binary operator.
the start value
the binary operator
the result of inserting op
between consecutive elements of this collection or iterator,
going right to left with the start value z
on the right:
op(x_1, op(x_2, ... op(x_n, z)...))
where x_{1}, ..., x_{n}
are the elements of this collection or iterator.
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
and reduce
. It has similar
semantics, but does not require the result to be a supertype of the
element type. It traverses the elements in different partitions
sequentially, using seqop
to update the result, and then applies
combop
to results from different partitions. The implementation of
this operation may operate on an arbitrary number of collection
partitions, so combop
may be invoked an arbitrary number of times.
For example, one might want to process some elements and then produce
a Set
. In this case, seqop
would process an element and append it
to the list, while combop
would concatenate two lists from different
partitions together. The initial value z
would be an empty set.
pc.aggregate(Set[Int]())(_ += process(_), _ ++ _)
Another example is calculating geometric mean from a collection of doubles (one would typically require big doubles for this).
the type of accumulated results
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 or 0
for summation) and may be evaluated
more than once
an operator used to accumulate results within a partition
an associative operator used to combine results from different partitions
Selects an element by its index in the general sequence.
Selects an element by its index in the general 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
The index to select.
the element of this general sequence at index idx
, where 0
indicates the first element.
if idx
does not satisfy 0 <= idx < length
.
A method that should be called from every well-designed equals method that is open to be overridden in a subclass.
A method that should be called from every well-designed equals method that is open to be overridden in a subclass. See Programming in Scala, Chapter 28 for discussion and design.
the value being probed for possible equality
true if this instance can possibly equal that
, otherwise false
Tests whether every element of this general sequence relates to the corresponding element of another sequence by satisfying a test predicate.
Tests whether every element of this general sequence relates to the corresponding element of another sequence by satisfying a test predicate.
the type of the elements of that
the other sequence
the test predicate, which relates elements from both sequences
true
if both sequences have the same length and
p(x, y)
is true
for all corresponding elements x
of this general sequence
and y
of that
, otherwise false
.
Counts the number of elements in the collection or iterator which satisfy a predicate.
Counts the number of elements in the collection or iterator which satisfy a predicate.
the predicate used to test elements.
the number of elements satisfying the predicate p
.
Builds a new general sequence from this general sequence without any duplicate elements.
Builds a new general sequence from this general sequence without any duplicate elements.
Note: will not terminate for infinite-sized collections.
A new general sequence which contains the first occurrence of every element of this general sequence.
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.
the number of elements to drop from this general collection.
a general collection consisting of all elements of this general collection except the first n
ones, or else the
empty general collection, if this general collection has less than n
elements.
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.
The predicate used to test elements.
the longest suffix of this general collection whose first element
does not satisfy the predicate p
.
Tests whether this general sequence ends with the given sequence.
Tests whether this general sequence ends with the given sequence.
Note: will not terminate for infinite-sized collections.
the sequence to test
true
if this general sequence has that
as a suffix, false
otherwise.
Selects all elements of this general collection which satisfy a predicate.
Selects all elements of this general collection which satisfy a predicate.
the predicate used to test elements.
a new general collection consisting of all elements of this general collection that satisfy the given
predicate p
. Their order may not be preserved.
Selects all elements of this general collection which do not satisfy a predicate.
Selects all elements of this general collection which do not satisfy a predicate.
the predicate used to test elements.
a new general collection consisting of all elements of this general collection that do not satisfy the given
predicate p
. Their order may not be preserved.
Finds the first element of the collection or iterator satisfying a predicate, if any.
Finds the first element of the collection or iterator 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.
the predicate used to test elements.
an option value containing the first element in the collection or iterator
that satisfies p
, or None
if none exists.
Folds the elements of this collection or iterator using the specified associative binary operator.
Folds the elements of this collection or iterator using the specified associative binary operator.
The order in which operations are performed on elements is unspecified and may be nondeterministic.
a type parameter for the binary operator, a supertype of A
.
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.)
a binary operator that must be associative
the result of applying fold operator op
between all the elements and z
Applies a binary operator to a start value and all elements of this collection or iterator, going left to right.
Applies a binary operator to a start value and all elements of this collection 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.
the result type of the binary operator.
the start value.
the binary operator.
the result of inserting op
between consecutive elements of this collection or iterator,
going left to right with the start value z
on the left:
op(...op(z, x_1), x_2, ..., x_n)
where x_{1}, ..., x_{n}
are the elements of this collection or iterator.
Applies a binary operator to all elements of this collection or iterator and a start value, going right to left.
Applies a binary operator to all elements of this collection or iterator 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.
the result type of the binary operator.
the start value.
the binary operator.
the result of inserting op
between consecutive elements of this collection or iterator,
going right to left with the start value z
on the right:
op(x_1, op(x_2, ... op(x_n, z)...))
where x_{1}, ..., x_{n}
are the elements of this collection or iterator.
Partitions this general collection into a map of general collections according to some discriminator function.
Partitions this general collection into a map of general 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 general collection.
the type of keys returned by the discriminator function.
the discriminator function.
A map from keys to general 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 general collection of those elements x
for which f(x)
equals k
.
Selects the first element of this general collection.
Selects the first element of this general collection.
Note: might return different results for different runs, unless the underlying collection type is ordered.
the first element of this general collection.
if the general collection is empty.
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.
the first element of this general collection if it is nonempty,
None
if it is empty.
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.
the predicate used to test elements.
the start index
the index >= from
of the first element of this general sequence that satisfies the predicate p
,
or -1
, if none exists.
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.
a general collection consisting of all elements of this general collection except the last one.
if the general collection is empty.
Tests whether the collection or iterator is empty.
Tests whether the collection or iterator is empty.
true
if the collection or iterator contains no elements, false
otherwise.
Tests whether this general collection can be repeatedly traversed.
Tests whether this general collection can be repeatedly traversed.
true
Selects the last element.
Selects the last element.
Note: might return different results for different runs, unless the underlying collection type is ordered.
The last element of this general collection.
If the general collection is empty.
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.
the predicate used to test elements.
the index <= end
of the last element of this general sequence that satisfies the predicate p
,
or -1
, if none exists.
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.
the last element of this general collection$ if it is nonempty,
None
if it is empty.
The length of the general sequence.
The length of the general sequence.
Note: will not terminate for infinite-sized collections.
Note: xs.length
and xs.size
yield the same result.
the number of elements in this general sequence.
Displays all elements of this collection or iterator in a string.
Displays all elements of this collection or iterator in a string.
a string representation of this collection or iterator. In the resulting string
the string representations (w.r.t. the method toString
)
of all elements of this collection or iterator follow each other without any
separator string.
Displays all elements of this collection or iterator in a string using a separator string.
Displays all elements of this collection or iterator in a string using a separator string.
the separator string.
a string representation of this collection or iterator. In the resulting string
the string representations (w.r.t. the method toString
)
of all elements of this collection or iterator are separated by the string sep
.
List(1, 2, 3).mkString("|") = "1|2|3"
Displays all elements of this collection or iterator in a string using start, end, and separator strings.
Displays all elements of this collection or iterator in a string using start, end, and separator strings.
the starting string.
the separator string.
the ending string.
a string representation of this collection or iterator. The resulting string
begins with the string start
and ends with the string
end
. Inside, the string representations (w.r.t. the method
toString
) of all elements of this collection or iterator are separated by
the string sep
.
List(1, 2, 3).mkString("(", "; ", ")") = "(1; 2; 3)"
Tests whether the collection or iterator is not empty.
Tests whether the collection or iterator is not empty.
true
if the collection or iterator contains at least one element, false
otherwise.
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.
a combiner for the parallel collection of type ParRepr
Partitions this general collection in two general collections according to a predicate.
Partitions this general collection in two general collections according to a predicate.
the predicate on which to partition.
a pair of general collections: the first general collection consists of all elements that
satisfy the predicate p
and the second general collection consists of all elements
that don't. The relative order of the elements in the resulting general collections
may not be preserved.
Reduces the elements of this collection or iterator using the specified associative binary operator.
Reduces the elements of this collection or iterator using the specified associative binary operator.
The order in which operations are performed on elements is unspecified and may be nondeterministic.
A type parameter for the binary operator, a supertype of A
.
A binary operator that must be associative.
The result of applying reduce operator op
between all the elements if the collection or iterator is nonempty.
if this collection or iterator is empty.
Optionally applies a binary operator to all elements of this collection or iterator, going left to right.
Optionally applies a binary operator to all elements of this collection 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.
the result type of the binary operator.
the binary operator.
an option value containing the result of reduceLeft(op)
is this collection or iterator is nonempty,
None
otherwise.
Reduces the elements of this collection or iterator, if any, using the specified associative binary operator.
Reduces the elements of this collection 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.
A type parameter for the binary operator, a supertype of A
.
A binary operator that must be associative.
An option value containing result of applying reduce operator op
between all
the elements if the collection is nonempty, and None
otherwise.
Applies a binary operator to all elements of this collection or iterator, going right to left.
Applies a binary operator to all elements of this collection 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.
the result type of the binary operator.
the binary operator.
the result of inserting op
between consecutive elements of this collection or iterator,
going right to left:
op(x_1, op(x_2, ..., op(x_{n-1}, x_n)...))
where x_{1}, ..., x_{n}
are the elements of this collection or iterator.
if this collection or iterator is empty.
Optionally applies a binary operator to all elements of this collection or iterator, going right to left.
Optionally applies a binary operator to all elements of this collection 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.
the result type of the binary operator.
the binary operator.
an option value containing the result of reduceRight(op)
is this collection or iterator is nonempty,
None
otherwise.
Returns new general sequence with elements in reversed order.
Returns new general sequence with elements in reversed order.
Note: will not terminate for infinite-sized collections.
A new general sequence with all elements of this general sequence in reversed order.
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.
element type of the resulting collection
type of the resulting collection
neutral element for the operator op
the associative operator for the scan
combiner factory which provides a combiner
a new general collection containing the prefix scan of the elements in this general collection
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.
the type of the elements in the resulting collection
the actual type of the resulting collection
the initial value
the binary operator applied to the intermediate result and the element
an implicit value of class CanBuildFrom
which determines
the result class That
from the current representation type Repr
and
and the new element type B
.
collection with intermediate results
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)
the type of the elements in the resulting collection
the actual type of the resulting collection
the initial value
the binary operator applied to the intermediate result and the element
an implicit value of class CanBuildFrom
which determines
the result class That
from the current representation type Repr
and
and the new element type B
.
collection with intermediate results
(Changed in version 2.9.0) The behavior of scanRight
has changed. The previous behavior can be reproduced with scanRight.reverse.
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.
the predicate used to test elements.
the index where the search starts.
the length of the longest segment of this general sequence starting from index from
such that every element of the segment satisfies the predicate p
.
The size of this general collection.
The size of this general collection.
Note: will not terminate for infinite-sized collections.
the number of elements in this general collection.
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.
the lowest index to include from this general collection.
the lowest index to EXCLUDE from this general collection.
a general collection containing the elements greater than or equal to
index from
extending up to (but not including) index until
of this general collection.
Splits this general collection into a prefix/suffix pair according to a predicate.
Splits this general 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
predicate p
does not cause any side-effects.
Note: might return different results for different runs, unless the underlying collection type is ordered.
the test predicate
a pair consisting of the longest prefix of this general collection whose
elements all satisfy p
, and the rest of this general collection.
Splits this general collection into two at a given position.
Splits this general 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.
the position at which to split.
a pair of general collections consisting of the first n
elements of this general collection, and the other elements.
Tests whether this general sequence contains the given sequence at a given index.
Tests whether this general sequence contains the given sequence at a given index.
Note: If the both the receiver object this
and the argument
that
are infinite sequences this method may not terminate.
the sequence to test
the index where the sequence is searched.
true
if the sequence that
is contained in this general sequence at
index offset
, otherwise false
.
Defines the prefix of this object's toString
representation.
Defines the prefix of this object's toString
representation.
a string representation which starts the result of toString
applied to this general collection. By default the string prefix is the
simple name of the collection class general collection.
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.
a general collection consisting of all elements of this general collection except the first one.
if the general collection is empty.
Selects first n elements.
Selects first n elements.
Note: might return different results for different runs, unless the underlying collection type is ordered.
the number of elements to take from this general collection.
a general collection consisting only of the first n
elements of this general collection,
or else the whole general collection, if it has less than n
elements.
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.
The predicate used to test elements.
the longest prefix of this general collection whose elements all satisfy
the predicate p
.
Uses the contents of this collection or iterator to create a new mutable buffer.
Uses the contents of this collection or iterator to create a new mutable buffer.
Note: will not terminate for infinite-sized collections.
a buffer containing all elements of this collection or iterator.
Converts this collection or iterator to an indexed sequence.
Converts this collection or iterator to an indexed sequence.
Note: will not terminate for infinite-sized collections.
an indexed sequence containing all elements of this collection or iterator.
Converts this collection or iterator to an iterable collection.
Converts this collection or iterator to an iterable collection. Note that
the choice of target Iterable
is lazy in this default implementation
as this TraversableOnce
may be lazy and unevaluated (i.e. it may
be an iterator which is only traversable once).
Note: will not terminate for infinite-sized collections.
an Iterable
containing all elements of this collection or iterator.
Returns an Iterator over the elements in this collection or iterator.
Returns an Iterator over the elements in this collection or iterator. Will return the same Iterator if this instance is already an Iterator.
Note: will not terminate for infinite-sized collections.
an Iterator containing all elements of this collection or iterator.
Converts this collection or iterator to a list.
Converts this collection or iterator to a list.
Note: will not terminate for infinite-sized collections.
a list containing all elements of this collection or iterator.
Converts this general sequence to a sequence.
Converts this general sequence to a sequence. As with toIterable
, it's lazy
in this default implementation, as this TraversableOnce
may be
lazy and unevaluated.
Note: will not terminate for infinite-sized collections.
a sequence containing all elements of this general sequence.
Converts this collection or iterator to a set.
Converts this collection or iterator to a set.
Note: will not terminate for infinite-sized collections.
a set containing all elements of this collection or iterator.
Converts this collection or iterator to a stream.
Converts this collection or iterator to a stream.
Note: will not terminate for infinite-sized collections.
a stream containing all elements of this collection or iterator.
Converts this collection or iterator to an unspecified Traversable.
Converts this collection or iterator to an unspecified Traversable. Will return the same collection if this instance is already Traversable.
Note: will not terminate for infinite-sized collections.
a Traversable containing all elements of this collection or iterator.
Converts this collection or iterator to a Vector.
Converts this collection or iterator to a Vector.
Note: will not terminate for infinite-sized collections.
a vector containing all elements of this collection or iterator.
[use case] Returns a new general sequence containing the elements from the left hand operand followed by the elements from the right hand operand.
Returns a new general sequence containing the elements from the left hand operand followed by the elements from the right hand operand. The element type of the general sequence is the most specific superclass encompassing the element types of the two operands.
Example:
scala> val a = List(1) a: List[Int] = List(1) scala> val b = List(2) b: List[Int] = List(2) scala> val c = a ++ b c: List[Int] = List(1, 2) scala> val d = List('a') d: List[Char] = List(a) scala> val e = c ++ d e: List[AnyVal] = List(1, 2, a)
the element type of the returned collection.
the traversable to append.
a new general sequence which contains all elements of this general sequence
followed by all elements of that
.
[use case] A copy of the general sequence with an element prepended.
A copy of the general 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 general 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)
the prepended element
a new general sequence consisting of elem
followed
by all elements of this general sequence.
[use case] A copy of this general sequence with an element appended.
A copy of this general 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)
the appended element
a new general sequence consisting of
all elements of this general sequence followed by elem
.
[use case] Builds a new collection by applying a partial function to all elements of this general sequence on which the function is defined.
Builds a new collection by applying a partial function to all elements of this general sequence on which the function is defined.
the element type of the returned collection.
the partial function which filters and maps the general sequence.
a new general 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.
[use case] Copies values of this general sequence to an array.
Copies values of this general sequence to an array.
Fills the given array xs
with values of this general sequence, beginning at index start
.
Copying will stop once either the end of the current general sequence is reached,
or the end of the array is reached.
Note: will not terminate for infinite-sized collections.
the array to fill.
the starting index.
[use case] Copies values of this general sequence to an array.
Copies values of this general sequence to an array.
Fills the given array xs
with values of this general sequence.
Copying will stop once either the end of the current general sequence is reached,
or the end of the array is reached.
Note: will not terminate for infinite-sized collections.
the array to fill.
[use case] Computes the multiset difference between this general sequence and another sequence.
Computes the multiset difference between this general sequence and another sequence.
Note: will not terminate for infinite-sized collections.
the sequence of elements to remove
a new general sequence which contains all elements of this general sequence
except some of occurrences of elements that also appear in that
.
If an element value x
appears
n times in that
, then the first n occurrences of x
will not form
part of the result, but any following occurrences will.
The equals method for arbitrary sequences.
The equals method for arbitrary sequences. Compares this sequence to some other object.
The object to compare the sequence to
true
if that
is a sequence that has the same elements as
this sequence in the same order, false
otherwise
[use case] Builds a new collection by applying a function to all elements of this general sequence and using the elements of the resulting collections.
Builds a new collection by applying a function to all elements of this general 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 general 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)
the element type of the returned collection.
the function to apply to each element.
a new general sequence resulting from applying the given collection-valued function
f
to each element of this general sequence and concatenating the results.
[use case] Applies a function f
to all elements of this general sequence.
Applies a function f
to all elements of this general sequence.
the function that is applied for its side-effect to every element.
The result of function f
is discarded.
Returns string formatted according to given format
string.
Returns string formatted according to given format
string.
Format strings are as for String.format
(@see java.lang.String.format).
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.
[use case] Finds index of first occurrence of some value in this general sequence after or at some start index.
Finds index of first occurrence of some value in this general sequence after or at some start index.
Note: may not terminate for infinite-sized collections.
the element value to search for.
the start index
the index >= from
of the first element of this general sequence that is equal (as determined by ==
)
to elem
, or -1
, if none exists.
[use case] Finds index of first occurrence of some value in this general sequence.
Finds index of first occurrence of some value in this general sequence.
Note: may not terminate for infinite-sized collections.
the element value to search for.
the index of the first element of this general sequence that is equal (as determined by ==
)
to elem
, or -1
, if none exists.
Finds index of first element satisfying some predicate.
Finds index of first element satisfying some predicate.
Note: may not terminate for infinite-sized collections.
the predicate used to test elements.
the index of the first element of this general sequence that satisfies the predicate p
,
or -1
, if none exists.
[use case] Computes the multiset intersection between this general sequence and another sequence.
Computes the multiset intersection between this general sequence and another sequence.
Note: may not terminate for infinite-sized collections.
the sequence of elements to intersect with.
a new general sequence which contains all elements of this general sequence
which also appear in that
.
If an element value x
appears
n times in that
, then the first n occurrences of x
will be retained
in the result, but any following occurrences will be omitted.
Tests whether this general sequence contains given index.
Tests whether this general sequence contains given index.
The implementations of methods apply
and isDefinedAt
turn a Seq[A]
into
a PartialFunction[Int, A]
.
the index to test
true
if this general sequence contains an element at position idx
, false
otherwise.
[use case] Finds index of last occurrence of some value in this general sequence before or at a given end index.
Finds index of last occurrence of some value in this general sequence before or at a given end index.
the element value to search for.
the end index.
the index <= end
of the last element of this general sequence that is equal (as determined by ==
)
to elem
, or -1
, if none exists.
[use case] Finds index of last occurrence of some value in this general sequence.
Finds index of last occurrence of some value in this general sequence.
Note: will not terminate for infinite-sized collections.
the element value to search for.
the index of the last element of this general sequence that is equal (as determined by ==
)
to elem
, or -1
, if none exists.
Finds index of last element satisfying some predicate.
Finds index of last element satisfying some predicate.
Note: will not terminate for infinite-sized collections.
the predicate used to test elements.
the index of the last element of this general sequence that satisfies the predicate p
,
or -1
, if none exists.
[use case] Builds a new collection by applying a function to all elements of this general sequence.
Builds a new collection by applying a function to all elements of this general sequence.
the element type of the returned collection.
the function to apply to each element.
a new general sequence resulting from applying the given function
f
to each element of this general sequence and collecting the results.
[use case] Finds the largest element.
Finds the largest element.
the largest element of this general sequence.
[use case] Finds the first element which yields the largest value measured by function f.
Finds the first element which yields the largest value measured by function f.
The result type of the function f.
The measuring function.
the first element of this general sequence with the largest value measured by function f.
[use case] Finds the smallest element.
Finds the smallest element.
the smallest element of this general sequence
[use case] Finds the first element which yields the smallest value measured by function f.
Finds the first element which yields the smallest value measured by function f.
The result type of the function f.
The measuring function.
the first element of this general sequence with the smallest value measured by function f.
[use case] A copy of this general sequence with an element value appended until a given target length is reached.
A copy of this general sequence with an element value appended until a given target length is reached.
the target length
the padding value
a new general sequence consisting of
all elements of this general sequence followed by the minimal number of occurrences of elem
so
that the resulting general sequence has a length of at least len
.
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
or mutable.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.
a parallel implementation of this collection
[use case] Produces a new general sequence where a slice of elements in this general sequence is replaced by another sequence.
Produces a new general sequence where a slice of elements in this general sequence is replaced by another sequence.
the index of the first replaced element
the number of elements to drop in the original general sequence
a new general sequence consisting of all elements of this general sequence
except that replaced
elements starting from from
are replaced
by patch
.
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.
the predicate used to test elements.
the length of the longest prefix of this general sequence
such that every element of the segment satisfies the predicate p
.
[use case] Multiplies up the elements of this collection.
Multiplies up the elements of this collection.
the product of all elements in this general sequence of numbers of type Int
.
Instead of Int
, any other type T
with an implicit Numeric[T]
implementation
can be used as element type of the general sequence and as result type of product
.
Examples of such types are: Long
, Float
, Double
, BigInt
.
[use case] Builds a new collection by applying a function to all elements of this general sequence and collecting the results in reversed order.
Builds a new collection by applying a function to all elements of this general sequence and collecting the results in reversed order.
Note: will not terminate for infinite-sized collections.
Note: xs.reverseMap(f)
is the same as xs.reverse.map(f)
but might be more efficient.
the element type of the returned collection.
the function to apply to each element.
a new general sequence resulting from applying the given function
f
to each element of this general sequence and collecting the results in reversed order.
[use case] Checks if the other iterable collection contains the same elements in the same order as this general sequence.
Checks if the other iterable collection contains the same elements in the same order as this general sequence.
Note: might return different results for different runs, unless the underlying collection type is ordered.
Note: will not terminate for infinite-sized collections.
the collection to compare with.
true
, if both collections contain the same elements in the same order, false
otherwise.
Tests whether this general sequence starts with the given sequence.
Tests whether this general sequence starts with the given sequence.
the sequence to test
true
if this collection has that
as a prefix, false
otherwise.
[use case] Sums up the elements of this collection.
Sums up the elements of this collection.
the sum of all elements in this general sequence of numbers of type Int
.
Instead of Int
, any other type T
with an implicit Numeric[T]
implementation
can be used as element type of the general sequence and as result type of sum
.
Examples of such types are: Long
, Float
, Double
, BigInt
.
[use case] Converts this general sequence into another by copying all elements.
Converts this general sequence into another by copying all elements.
Note: will not terminate for infinite-sized collections.
The collection type to build.
a new collection containing all elements of this general sequence.
[use case] Converts this general sequence to an array.
Converts this general sequence to an array.
Note: will not terminate for infinite-sized collections.
an array containing all elements of this general sequence.
An ClassTag
must be available for the element type of this general sequence.
[use case] Converts this general sequence to a map.
Converts this general 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.
a map of type immutable.Map[T, U]
containing all key/value pairs of type (T, U)
of this general sequence.
[use case] Produces a new sequence which contains all elements of this general sequence and also all elements of a given sequence.
Produces a new sequence which contains all elements of this general sequence and also all elements of
a given sequence. xs union ys
is equivalent to xs ++ ys
.
Another way to express this
is that xs union ys
computes the order-presevring multi-set union of xs
and ys
.
union
is hence a counter-part of diff
and intersect
which also work on multi-sets.
Note: will not terminate for infinite-sized collections.
the sequence to add.
a new general sequence which contains all elements of this general sequence
followed by all elements of that
.
[use case] A copy of this general sequence with one single replaced element.
A copy of this general sequence with one single replaced element.
the position of the replacement
the replacing element
a copy of this general sequence with the element at position index
replaced by elem
.
[use case] Returns a general sequence formed from this general sequence and another iterable collection by combining corresponding elements in pairs.
Returns a general sequence formed from this general 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.
Note: might return different results for different runs, unless the underlying collection type is ordered.
the type of the second half of the returned pairs
The iterable providing the second half of each result pair
a new general sequence containing pairs consisting of
corresponding elements of this general sequence and that
. The length
of the returned collection is the minimum of the lengths of this general sequence and that
.
[use case] Returns a general sequence formed from this general sequence and another iterable collection by combining corresponding elements in pairs.
Returns a general sequence formed from this general 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.
Note: might return different results for different runs, unless the underlying collection type is ordered.
the type of the second half of the returned pairs
The iterable providing the second half of each result pair
the element to be used to fill up the result if this general sequence is shorter than that
.
the element to be used to fill up the result if that
is shorter than this general sequence.
a new general sequence containing pairs consisting of
corresponding elements of this general sequence and that
. The length
of the returned collection is the maximum of the lengths of this general sequence and that
.
If this general sequence is shorter than that
, thisElem
values are used to pad the result.
If that
is shorter than this general sequence, thatElem
values are used to pad the result.
[use case] Zips this general sequence with its indices.
Zips this general sequence with its indices.
Note: might return different results for different runs, unless the underlying collection type is ordered.
A new general sequence containing pairs consisting of all elements of this
general sequence paired with their index. Indices start at 0
.
List("a", "b", "c").zipWithIndex = List(("a", 0), ("b", 1), ("c", 2))
A template trait for all sequences which may be traversed in parallel.