LinkedHashSet

This class implements mutable sets using a hashtable. The iterator and all traversal methods of this class visit elements in the order they were inserted.

Type parameters:
A

the type of the elements contained in this set.

Companion:
object
Source:
LinkedHashSet.scala

Type members

Types

type Entry = Entry[A]

Value members

Concrete methods

def addOne(elem: A): LinkedHashSet.this.type

Adds a single element to this linked hash set.

Adds a single element to this linked hash set.

Value parameters:
elem

the element to add.

Returns:

the linked hash set itself

Source:
LinkedHashSet.scala
override def clear(): Unit

Clears the contents of this builder.

Clears the contents of this builder. After execution of this method the builder will contain no elements.

Definition Classes
Source:
LinkedHashSet.scala
override def foreach[U](f: A => U): Unit

Apply f to each element for its side effects Note: [U] parameter needed to help scalac's type inference.

Apply f to each element for its side effects Note: [U] parameter needed to help scalac's type inference.

Definition Classes
Source:
LinkedHashSet.scala
override def head: A

Selects the first element of this linked hash set.

Selects the first element of this linked hash set.

Returns:

the first element of this linked hash set.

Throws:
NoSuchElementException

if the linked hash set is empty.

Definition Classes
Source:
LinkedHashSet.scala
override def headOption: Option[A]

Optionally selects the first element.

Optionally selects the first element.

Returns:

the first element of this linked hash set if it is nonempty, None if it is empty.

Definition Classes
Source:
LinkedHashSet.scala
override def isEmpty: Boolean

Tests whether the linked hash set is empty.

Tests whether the linked hash set is empty.

Note: Implementations in subclasses that are not repeatedly traversable must take care not to consume any elements when isEmpty is called.

Returns:

true if the linked hash set contains no elements, false otherwise.

Definition Classes
Source:
LinkedHashSet.scala

The companion object of this linked hash set, providing various factory methods.

The companion object of this linked hash set, providing various factory methods.

Note:

When implementing a custom collection type and refining CC to the new type, this method needs to be overridden to return a factory for the new type (the compiler will issue an error otherwise).

Definition Classes
Source:
LinkedHashSet.scala

Iterator can be used only once

Iterator can be used only once

Source:
LinkedHashSet.scala
override def knownSize: Int
Returns:

The number of elements in the collection under construction, if it can be cheaply computed, -1 otherwise. The default implementation always returns -1.

Definition Classes
Source:
LinkedHashSet.scala
override def last: A

Selects the last element.

Selects the last element.

Returns:

The last element of this linked hash set.

Throws:
NoSuchElementException

If the linked hash set is empty.

Definition Classes
Source:
LinkedHashSet.scala
override def lastOption: Option[A]

Optionally selects the last element.

Optionally selects the last element.

Returns:

the last element of this linked hash set$ if it is nonempty, None if it is empty.

Definition Classes
Source:
LinkedHashSet.scala
override def remove(elem: A): Boolean

Removes an element from this set.

Removes an element from this set.

Value parameters:
elem

the element to be removed

Returns:

true if this set contained the element before it was removed

Definition Classes
Source:
LinkedHashSet.scala
override def size: Int

The size of this linked hash set.

The size of this linked hash set.

Returns:

the number of elements in this linked hash set.

Definition Classes
Source:
LinkedHashSet.scala
def subtractOne(elem: A): LinkedHashSet.this.type

Removes a single element from this linked hash set.

Removes a single element from this linked hash set.

Value parameters:
elem

the element to remove.

Returns:

the linked hash set itself

Source:
LinkedHashSet.scala

Inherited methods

final def &(that: Set[A]): C

Alias for intersect

Alias for intersect

Inherited from:
SetOps
Source:
Set.scala
final def &~(that: Set[A]): C

Alias for diff

Alias for diff

Inherited from:
SetOps
Source:
Set.scala
final def ++[B >: A](suffix: IterableOnce[B]): CC[B]

Alias for concat

Alias for concat

Inherited from:
IterableOps
Source:
Iterable.scala
final def ++(that: IterableOnce[A]): C

Alias for concat

Alias for concat

Inherited from:
SetOps
Source:
Set.scala
final def ++=(xs: IterableOnce[A]): Growable.this.type

Alias for addAll

Alias for addAll

Inherited from:
Growable
Source:
Growable.scala
final def +=(elem: A): Growable.this.type

Alias for addOne

Alias for addOne

Inherited from:
Growable
Source:
Growable.scala
final def --=(xs: IterableOnce[A]): Shrinkable.this.type

Alias for subtractAll

Alias for subtractAll

Inherited from:
Shrinkable
Source:
Shrinkable.scala
final def -=(elem: A): Shrinkable.this.type

Alias for subtractOne

Alias for subtractOne

Inherited from:
Shrinkable
Source:
Shrinkable.scala
def add(elem: A): Boolean

Check whether the set contains the given element, and add it if not.

Check whether the set contains the given element, and add it if not.

Value parameters:
elem

the element to be added

Returns:

true if the element was added

Inherited from:
SetOps
Source:
Set.scala
def addAll(xs: IterableOnce[A]): Growable.this.type

Adds all elements produced by an IterableOnce to this growable collection.

Adds all elements produced by an IterableOnce to this growable collection.

Value parameters:
xs

the IterableOnce producing the elements to add.

Returns:

the growable collection itself.

Inherited from:
Growable
Source:
Growable.scala

Appends all elements of this collection to a string builder.

Appends all elements of this collection to a string builder. The written text consists of the string representations (w.r.t. the method toString) of all elements of this collection 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
Value parameters:
b

the string builder to which elements are appended.

Returns:

the string builder b to which elements were appended.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala

Appends all elements of this collection to a string builder using a separator string.

Appends all elements of this collection 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 collection, separated by the string sep.

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
Value parameters:
b

the string builder to which elements are appended.

sep

the separator string.

Returns:

the string builder b to which elements were appended.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala

Appends all elements of this collection to a string builder using start, end, and separator strings.

Appends all elements of this collection to a string builder using start, end, and separator strings. The written text 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 are separated by the string sep.

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)
Value parameters:
b

the string builder to which elements are appended.

end

the ending string.

sep

the separator string.

start

the starting string.

Returns:

the string builder b to which elements were appended.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def andThen[A](g: Boolean => A): T1 => A

Composes two instances of Function1 in a new Function1, with this function applied first.

Composes two instances of Function1 in a new Function1, with this function applied first.

Type parameters:
A

the result type of function g

Value parameters:
g

a function R => A

Returns:

a new function f such that f(x) == g(apply(x))

Inherited from:
Function1
Source:
Function1.scala
final def apply(elem: A): Boolean

Tests if some element is contained in this set.

Tests if some element is contained in this set.

This method is equivalent to contains. It allows sets to be interpreted as predicates.

Value parameters:
elem

the element to test for membership.

Returns:

true if elem is contained in this set, false otherwise.

Inherited from:
SetOps
Source:
Set.scala
def canEqual(that: Any): Boolean

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.

Value parameters:
that

the value being probed for possible equality

Returns:

true if this instance can possibly equal that, otherwise false

Inherited from:
Set
Source:
Set.scala
override def clone(): C

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.

Note:

not specified by SLS as a member of AnyRef

Definition Classes
Inherited from:
SetOps
Source:
Set.scala
override def collect[B](pf: PartialFunction[A, B]): CC[B]

Builds a new iterable collection by applying a partial function to all elements of this iterable collection on which the function is defined.

Builds a new iterable collection by applying a partial function to all elements of this iterable collection on which the function is defined.

Type parameters:
B

the element type of the returned iterable collection.

Value parameters:
pf

the partial function which filters and maps the iterable collection.

Returns:

a new iterable collection 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
Inherited from:
StrictOptimizedIterableOps
Source:
StrictOptimizedIterableOps.scala
def collectFirst[B](pf: PartialFunction[A, B]): Option[B]

Finds the first element of the collection for which the given partial function is defined, and applies the partial function to it.

Finds the first element of the collection 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.

Value parameters:
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.

Example:

Seq("a", 1, 5L).collectFirst({ case x: Int => x*10 }) = Some(10)

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def compose[A](g: A => A): A => R

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.

Type parameters:
A

the type to which function g can be applied

Value parameters:
g

a function A => T1

Returns:

a new function f such that f(x) == apply(g(x))

Inherited from:
Function1
Source:
Function1.scala
def concat[B >: A](suffix: IterableOnce[B]): CC[B]

Returns a new iterable collection containing the elements from the left hand operand followed by the elements from the right hand operand.

Returns a new iterable collection containing the elements from the left hand operand followed by the elements from the right hand operand. The element type of the iterable collection is the most specific superclass encompassing the element types of the two operands.

Type parameters:
B

the element type of the returned collection.

Value parameters:
suffix

the traversable to append.

Returns:

a new iterable collection which contains all elements of this iterable collection followed by all elements of suffix.

Inherited from:
IterableOps
Source:
Iterable.scala
def concat(that: IterableOnce[A]): C

Creates a new set by adding all elements contained in another collection to this set, omitting duplicates.

Creates a new set by adding all elements contained in another collection to this set, omitting duplicates.

This method takes a collection of elements and adds all elements, omitting duplicates, into set.

Example:

scala> val a = Set(1, 2) concat Set(2, 3)
a: scala.collection.immutable.Set[Int] = Set(1, 2, 3)
Value parameters:
that

the collection containing the elements to add.

Returns:

a new set with the given elements added, omitting duplicates.

Inherited from:
SetOps
Source:
Set.scala
def copyToArray[B >: A](xs: Array[B], start: Int, len: Int): Int

Copy elements to an array, returning the number of elements written.

Copy elements to an array, returning the number of elements written.

Fills the given array xs starting at index start with at most len elements of this collection.

Copying will stop once either all the elements of this collection have been copied, or the end of the array is reached, or len elements have been copied.

Type parameters:
B

the type of the elements of the array.

Value parameters:
len

the maximal number of elements to copy.

start

the starting index of xs.

xs

the array to fill.

Returns:

the number of elements written to the array

Note:

Reuse: After calling this method, one should discard the iterator it was called on. Using it is undefined and subject to change.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def copyToArray[B >: A](xs: Array[B], start: Int): Int

Copy elements to an array, returning the number of elements written.

Copy elements to an array, returning the number of elements written.

Fills the given array xs starting at index start with values of this collection.

Copying will stop once either all the elements of this collection have been copied, or the end of the array is reached.

Type parameters:
B

the type of the elements of the array.

Value parameters:
start

the starting index of xs.

xs

the array to fill.

Returns:

the number of elements written to the array

Note:

Reuse: After calling this method, one should discard the iterator it was called on. Using it is undefined and subject to change.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def copyToArray[B >: A](xs: Array[B]): Int

Copy elements to an array, returning the number of elements written.

Copy elements to an array, returning the number of elements written.

Fills the given array xs starting at index start with values of this collection.

Copying will stop once either all the elements of this collection have been copied, or the end of the array is reached.

Type parameters:
B

the type of the elements of the array.

Value parameters:
xs

the array to fill.

Returns:

the number of elements written to the array

Note:

Reuse: After calling this method, one should discard the iterator it was called on. Using it is undefined and subject to change.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def corresponds[B](that: IterableOnce[B])(p: (A, B) => Boolean): Boolean

Tests whether every element of this collection's iterator relates to the corresponding element of another collection by satisfying a test predicate.

Tests whether every element of this collection's iterator relates to the corresponding element of another collection by satisfying a test predicate.

Note: will not terminate for infinite-sized collections.

Type parameters:
B

the type of the elements of that

Value parameters:
p

the test predicate, which relates elements from both collections

that

the other collection

Returns:

true if both collections have the same length and p(x, y) is true for all corresponding elements x of this iterator and y of that, otherwise false

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def count(p: A => Boolean): Int

Counts the number of elements in the collection which satisfy a predicate.

Counts the number of elements in the collection which satisfy a predicate.

Note: will not terminate for infinite-sized collections.

Value parameters:
p

the predicate used to test elements.

Returns:

the number of elements satisfying the predicate p.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def diff(that: Set[A]): C

Computes the difference of this set and another set.

Computes the difference of this set and another set.

Value parameters:
that

the set of elements to exclude.

Returns:

a set containing those elements of this set that are not also contained in the given set that.

Inherited from:
SetOps
Source:
Set.scala
def drop(n: Int): C

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.

Value parameters:
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 than n elements. If n is negative, don't drop any elements.

Inherited from:
IterableOps
Source:
Iterable.scala
override def dropRight(n: Int): C

The rest of the collection without its n last elements.

The rest of the collection without its n last elements. For linear, immutable collections this should avoid making a copy.

Note: Even when applied to a view or a lazy collection it will always force the elements.

Definition Classes
Inherited from:
StrictOptimizedIterableOps
Source:
StrictOptimizedIterableOps.scala
def dropWhile(p: A => Boolean): C

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.

Value parameters:
p

The predicate used to test elements.

Returns:

the longest suffix of this iterable collection whose first element does not satisfy the predicate p.

Inherited from:
IterableOps
Source:
Iterable.scala
override def empty: CC[A]

The empty iterable of the same type as this iterable

The empty iterable of the same type as this iterable

Returns:

an empty iterable of type C.

Definition Classes
Inherited from:
IterableFactoryDefaults
Source:
Iterable.scala
override def equals(that: Any): Boolean

Equality of sets is implemented using the lookup method contains.

Equality of sets is implemented using the lookup method contains. This method returns true if

  • the argument that is a Set,

  • the two sets have the same size, and

  • for every element this set, other.contains(element) == true.

The implementation of equals checks the canEqual method, so subclasses of Set can narrow down the equality to specific set types. The Set implementations in the standard library can all be compared, their canEqual methods return true.

Note: The equals method only respects the equality laws (symmetry, transitivity) if the two sets use the same element equivalence function in their lookup operation. For example, the element equivalence operation in a scala.collection.immutable.TreeSet is defined by its ordering. Comparing a TreeSet with a HashSet leads to unexpected results if ordering.equiv(e1, e2) (used for lookup in TreeSet) is different from e1 == e2 (used for lookup in HashSet).

scala> import scala.collection.immutable._
scala> val ord: Ordering[String] = _ compareToIgnoreCase _

scala> TreeSet("A")(ord) == HashSet("a")
val res0: Boolean = false

scala> HashSet("a") == TreeSet("A")(ord)
val res1: Boolean = true
Value parameters:
that

The set to which this set is compared

Returns:

true if the two sets are equal according to the description

Definition Classes
Set -> Equals -> Any
Inherited from:
Set
Source:
Set.scala
def exists(p: A => Boolean): Boolean

Tests whether a predicate holds for at least one element of this collection.

Tests whether a predicate holds for at least one element of this collection.

Note: may not terminate for infinite-sized collections.

Value parameters:
p

the predicate used to test elements.

Returns:

true if the given predicate p is satisfied by at least one element of this collection, otherwise false

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
override def filter(pred: A => Boolean): C

Selects all elements of this iterable collection which satisfy a predicate.

Selects all elements of this iterable collection which satisfy a predicate.

Value parameters:
p

the predicate used to test elements.

Returns:

a new iterable collection consisting of all elements of this iterable collection that satisfy the given predicate p. The order of the elements is preserved.

Definition Classes
Inherited from:
StrictOptimizedIterableOps
Source:
StrictOptimizedIterableOps.scala
def filterInPlace(p: A => Boolean): SetOps.this.type

Removes all elements from the set for which do not satisfy a predicate.

Removes all elements from the set for which do not satisfy a predicate.

Value parameters:
p

the predicate used to test elements. Only elements for which p returns true are retained in the set; all others are removed.

Inherited from:
SetOps
Source:
Set.scala
override def filterNot(pred: A => Boolean): C

Selects all elements of this iterable collection which do not satisfy a predicate.

Selects all elements of this iterable collection which do not satisfy a predicate.

Value parameters:
pred

the predicate used to test elements.

Returns:

a new iterable collection consisting of all elements of this iterable collection that do not satisfy the given predicate pred. Their order may not be preserved.

Definition Classes
Inherited from:
StrictOptimizedIterableOps
Source:
StrictOptimizedIterableOps.scala
def find(p: A => Boolean): Option[A]

Finds the first element of the collection satisfying a predicate, if any.

Finds the first element of the 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.

Value parameters:
p

the predicate used to test elements.

Returns:

an option value containing the first element in the collection that satisfies p, or None if none exists.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
override def flatMap[B](f: A => IterableOnce[B]): CC[B]

Builds a new iterable collection by applying a function to all elements of this iterable collection and using the elements of the resulting collections.

Builds a new iterable collection by applying a function to all elements of this iterable collection 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 iterable collection. 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: String) => 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)
Type parameters:
B

the element type of the returned collection.

Value parameters:
f

the function to apply to each element.

Returns:

a new iterable collection resulting from applying the given collection-valued function f to each element of this iterable collection and concatenating the results.

Definition Classes
Inherited from:
StrictOptimizedIterableOps
Source:
StrictOptimizedIterableOps.scala
override def flatten[B](implicit toIterableOnce: A => IterableOnce[B]): CC[B]

Converts this iterable collection of traversable collections into a iterable collection formed by the elements of these traversable collections.

Converts this iterable collection of traversable collections into a iterable collection formed by the elements of these traversable collections.

The resulting collection's type will be guided by the type of iterable collection. 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)
Type parameters:
B

the type of the elements of each traversable collection.

Value parameters:
asIterable

an implicit conversion which asserts that the element type of this iterable collection is a GenTraversable.

Returns:

a new iterable collection resulting from concatenating all element iterable collections.

Definition Classes
Inherited from:
StrictOptimizedIterableOps
Source:
StrictOptimizedIterableOps.scala
def fold[A1 >: A](z: A1)(op: (A1, A1) => A1): A1

Folds the elements of this collection using the specified associative binary operator.

Folds the elements of this collection using the specified associative binary operator. The default implementation in IterableOnce is equivalent to foldLeft but may be overridden for more efficient traversal orders.

The order in which operations are performed on elements is unspecified and may be nondeterministic.

Note: will not terminate for infinite-sized collections.

Type parameters:
A1

a type parameter for the binary operator, a supertype of A.

Value parameters:
op

a binary operator that must be associative.

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).

Returns:

the result of applying the fold operator op between all the elements and z, or z if this collection is empty.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def foldLeft[B](z: B)(op: (B, A) => B): B

Applies a binary operator to a start value and all elements of this collection, going left to right.

Applies a binary operator to a start value and all elements of this collection, 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.

Type parameters:
B

the result type of the binary operator.

Value parameters:
op

the binary operator.

z

the start value.

Returns:

the result of inserting op between consecutive elements of this collection, going left to right with the start value z on the left: op(...op(z, x1), x2, ..., xn) where x1, ..., xn are the elements of this collection. Returns z if this collection is empty.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def foldRight[B](z: B)(op: (A, B) => B): B

Applies a binary operator to all elements of this collection and a start value, going right to left.

Applies a binary operator to all elements of this 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.

Type parameters:
B

the result type of the binary operator.

Value parameters:
op

the binary operator.

z

the start value.

Returns:

the result of inserting op between consecutive elements of this collection, going right to left with the start value z on the right: op(x1, op(x2, ... op(xn, z)...)) where x1, ..., xn are the elements of this collection. Returns z if this collection is empty.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def forall(p: A => Boolean): Boolean

Tests whether a predicate holds for all elements of this collection.

Tests whether a predicate holds for all elements of this collection.

Note: may not terminate for infinite-sized collections.

Value parameters:
p

the predicate used to test elements.

Returns:

true if this collection is empty or the given predicate p holds for all elements of this collection, otherwise false.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
protected def fromSpecific(coll: IterableOnce[A]): CC[A]

Defines how to turn a given Iterable[A] into a collection of type C.

Defines how to turn a given Iterable[A] into a collection of type C.

This process can be done in a strict way or a non-strict way (ie. without evaluating the elements of the resulting collections). In other words, this methods defines the evaluation model of the collection.

Note:

When implementing a custom collection type and refining C to the new type, this method needs to be overridden (the compiler will issue an error otherwise). In the common case where C =:= CC[A], this can be done by mixing in the scala.collection.IterableFactoryDefaults trait, which implements the method using iterableFactory.

As witnessed by the @uncheckedVariance annotation, using this method might be unsound. However, as long as it is called with an Iterable[A] obtained from this collection (as it is the case in the implementations of operations where we use a View[A]), it is safe.

Inherited from:
IterableFactoryDefaults
Source:
Iterable.scala
def groupBy[K](f: A => K): Map[K, C]

Partitions this iterable collection into a map of iterable collections according to some discriminator function.

Partitions this iterable collection into a map of iterable collections according to some discriminator function.

Note: Even when applied to a view or a lazy collection it will always force the elements.

Type parameters:
K

the type of keys returned by the discriminator function.

Value parameters:
f

the discriminator function.

Returns:

A map from keys to iterable 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 iterable collection of those elements x for which f(x) equals k.

Inherited from:
IterableOps
Source:
Iterable.scala
def groupMap[K, B](key: A => K)(f: A => B): Map[K, CC[B]]

Partitions this iterable collection into a map of iterable collections according to a discriminator function key.

Partitions this iterable collection into a map of iterable collections according to a discriminator function key. Each element in a group is transformed into a value of type B using the value function.

It is equivalent to groupBy(key).mapValues(_.map(f)), but more efficient.

case class User(name: String, age: Int)

def namesByAge(users: Seq[User]): Map[Int, Seq[String]] =
  users.groupMap(_.age)(_.name)

Note: Even when applied to a view or a lazy collection it will always force the elements.

Type parameters:
B

the type of values returned by the transformation function

K

the type of keys returned by the discriminator function

Value parameters:
f

the element transformation function

key

the discriminator function

Inherited from:
IterableOps
Source:
Iterable.scala
def groupMapReduce[K, B](key: A => K)(f: A => B)(reduce: (B, B) => B): Map[K, B]

Partitions this iterable collection into a map according to a discriminator function key.

Partitions this iterable collection into a map according to a discriminator function key. All the values that have the same discriminator are then transformed by the f function and then reduced into a single value with the reduce function.

It is equivalent to groupBy(key).mapValues(_.map(f).reduce(reduce)), but more efficient.

def occurrences[A](as: Seq[A]): Map[A, Int] =
  as.groupMapReduce(identity)(_ => 1)(_ + _)

Note: Even when applied to a view or a lazy collection it will always force the elements.

Inherited from:
IterableOps
Source:
Iterable.scala
def grouped(size: Int): Iterator[C]

Partitions elements in fixed size iterable collections.

Partitions elements in fixed size iterable collections.

Value parameters:
size

the number of elements per group

Returns:

An iterator producing iterable collections of size size, except the last will be less than size size if the elements don't divide evenly.

See also:
Inherited from:
IterableOps
Source:
Iterable.scala
override def hashCode(): Int

Calculate a hash code value for the object.

Calculate a hash code value for the object.

The default hashing algorithm is platform dependent.

Note that it is allowed for two objects to have identical hash codes (o1.hashCode.equals(o2.hashCode)) yet not be equal (o1.equals(o2) returns false). A degenerate implementation could always return 0. However, it is required that if two objects are equal (o1.equals(o2) returns true) that they have identical hash codes (o1.hashCode.equals(o2.hashCode)). Therefore, when overriding this method, be sure to verify that the behavior is consistent with the equals method.

Returns:

the hash code value for this object.

Definition Classes
Set -> Any
Inherited from:
Set
Source:
Set.scala
def init: C

The initial part of the collection without its last element.

The initial part of the collection without its last element.

Note: Even when applied to a view or a lazy collection it will always force the elements.

Inherited from:
IterableOps
Source:
Iterable.scala
def inits: Iterator[C]

Iterates over the inits of this iterable collection.

Iterates over the inits of this iterable collection. The first value will be this iterable collection and the final one will be an empty iterable collection, with the intervening values the results of successive applications of init.

Note: Even when applied to a view or a lazy collection it will always force the elements.

Returns:

an iterator over all the inits of this iterable collection

Example:

List(1,2,3).inits = Iterator(List(1,2,3), List(1,2), List(1), Nil)

Inherited from:
IterableOps
Source:
Iterable.scala
def intersect(that: Set[A]): C

Computes the intersection between this set and another set.

Computes the intersection between this set and another set.

Value parameters:
that

the set to intersect with.

Returns:

a new set consisting of all elements that are both in this set and in the given set that.

Inherited from:
SetOps
Source:
Set.scala

Tests whether this iterable collection can be repeatedly traversed.

Tests whether this iterable collection can be repeatedly traversed. Always true for Iterables and false for Iterators unless overridden.

Returns:

true if it is repeatedly traversable, false otherwise.

Definition Classes
Inherited from:
IterableOps
Source:
Iterable.scala
def lazyZip[B](that: Iterable[B]): LazyZip2[A, B, Iterable]

Analogous to zip except that the elements in each collection are not consumed until a strict operation is invoked on the returned LazyZip2 decorator.

Analogous to zip except that the elements in each collection are not consumed until a strict operation is invoked on the returned LazyZip2 decorator.

Calls to lazyZip can be chained to support higher arities (up to 4) without incurring the expense of constructing and deconstructing intermediary tuples.

val xs = List(1, 2, 3)
val res = (xs lazyZip xs lazyZip xs lazyZip xs).map((a, b, c, d) => a + b + c + d)
// res == List(4, 8, 12)
Type parameters:
B

the type of the second element in each eventual pair

Value parameters:
that

the iterable providing the second element of each eventual pair

Returns:

a decorator LazyZip2 that allows strict operations to be performed on the lazily evaluated pairs or chained calls to lazyZip. Implicit conversion to Iterable[(A, B)] is also supported.

Inherited from:
Iterable
Source:
Iterable.scala
override def map[B](f: A => B): CC[B]

Builds a new iterable collection by applying a function to all elements of this iterable collection.

Builds a new iterable collection by applying a function to all elements of this iterable collection.

Type parameters:
B

the element type of the returned iterable collection.

Value parameters:
f

the function to apply to each element.

Returns:

a new iterable collection resulting from applying the given function f to each element of this iterable collection and collecting the results.

Definition Classes
Inherited from:
StrictOptimizedIterableOps
Source:
StrictOptimizedIterableOps.scala
def mapResult[NewTo](f: LinkedHashSet[A] => NewTo): Builder[A, NewTo]

A builder resulting from this builder my mapping the result using f.

A builder resulting from this builder my mapping the result using f.

Inherited from:
Builder
Source:
Builder.scala
def max[B >: A](implicit ord: Ordering[B]): A

Finds the largest element.

Finds the largest element.

Note: will not terminate for infinite-sized collections.

Type parameters:
B

The type over which the ordering is defined.

Value parameters:
ord

An ordering to be used for comparing elements.

Returns:

the largest element of this collection with respect to the ordering ord.

Throws:
UnsupportedOperationException

if this collection is empty.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def maxBy[B](f: A => B)(implicit cmp: Ordering[B]): A

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.

Note: will not terminate for infinite-sized collections.

Type parameters:
B

The result type of the function f.

Value parameters:
cmp

An ordering to be used for comparing elements.

f

The measuring function.

Returns:

the first element of this collection with the largest value measured by function f with respect to the ordering cmp.

Throws:
UnsupportedOperationException

if this collection is empty.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def maxByOption[B](f: A => B)(implicit cmp: Ordering[B]): Option[A]

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.

Note: will not terminate for infinite-sized collections.

Type parameters:
B

The result type of the function f.

Value parameters:
cmp

An ordering to be used for comparing elements.

f

The measuring function.

Returns:

an option value containing the first element of this collection with the largest value measured by function f with respect to the ordering cmp.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def maxOption[B >: A](implicit ord: Ordering[B]): Option[A]

Finds the largest element.

Finds the largest element.

Note: will not terminate for infinite-sized collections.

Type parameters:
B

The type over which the ordering is defined.

Value parameters:
ord

An ordering to be used for comparing elements.

Returns:

an option value containing the largest element of this collection with respect to the ordering ord.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def min[B >: A](implicit ord: Ordering[B]): A

Finds the smallest element.

Finds the smallest element.

Note: will not terminate for infinite-sized collections.

Type parameters:
B

The type over which the ordering is defined.

Value parameters:
ord

An ordering to be used for comparing elements.

Returns:

the smallest element of this collection with respect to the ordering ord.

Throws:
UnsupportedOperationException

if this collection is empty.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def minBy[B](f: A => B)(implicit cmp: Ordering[B]): A

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.

Note: will not terminate for infinite-sized collections.

Type parameters:
B

The result type of the function f.

Value parameters:
cmp

An ordering to be used for comparing elements.

f

The measuring function.

Returns:

the first element of this collection with the smallest value measured by function f with respect to the ordering cmp.

Throws:
UnsupportedOperationException

if this collection is empty.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def minByOption[B](f: A => B)(implicit cmp: Ordering[B]): Option[A]

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.

Note: will not terminate for infinite-sized collections.

Type parameters:
B

The result type of the function f.

Value parameters:
cmp

An ordering to be used for comparing elements.

f

The measuring function.

Returns:

an option value containing the first element of this collection with the smallest value measured by function f with respect to the ordering cmp.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def minOption[B >: A](implicit ord: Ordering[B]): Option[A]

Finds the smallest element.

Finds the smallest element.

Note: will not terminate for infinite-sized collections.

Type parameters:
B

The type over which the ordering is defined.

Value parameters:
ord

An ordering to be used for comparing elements.

Returns:

an option value containing the smallest element of this collection with respect to the ordering ord.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
final def mkString: String

Displays all elements of this collection in a string.

Displays all elements of this collection in a string.

Delegates to addString, which can be overridden.

Returns:

a string representation of this collection. In the resulting string the string representations (w.r.t. the method toString) of all elements of this collection follow each other without any separator string.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
final def mkString(sep: String): String

Displays all elements of this collection in a string using a separator string.

Displays all elements of this collection in a string using a separator string.

Delegates to addString, which can be overridden.

Value parameters:
sep

the separator string.

Returns:

a string representation of this collection. In the resulting string the string representations (w.r.t. the method toString) of all elements of this collection are separated by the string sep.

Example:

List(1, 2, 3).mkString("|") = "1|2|3"

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
final def mkString(start: String, sep: String, end: String): String

Displays all elements of this collection in a string using start, end, and separator strings.

Displays all elements of this collection in a string using start, end, and separator strings.

Delegates to addString, which can be overridden.

Value parameters:
end

the ending string.

sep

the separator string.

start

the starting string.

Returns:

a string representation of this collection. 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 are separated by the string sep.

Example:

List(1, 2, 3).mkString("(", "; ", ")") = "(1; 2; 3)"

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
protected def newSpecificBuilder: Builder[A, CC[A]]
Returns:

a strict builder for the same collection type. Note that in the case of lazy collections (e.g. scala.collection.View or scala.collection.immutable.LazyList), it is possible to implement this method but the resulting Builder will break laziness. As a consequence, operations should preferably be implemented with fromSpecific instead of this method.

Note:

When implementing a custom collection type and refining C to the new type, this method needs to be overridden (the compiler will issue an error otherwise). In the common case where C =:= CC[A], this can be done by mixing in the scala.collection.IterableFactoryDefaults trait, which implements the method using iterableFactory.

As witnessed by the @uncheckedVariance annotation, using this method might be unsound. However, as long as the returned builder is only fed with A values taken from this instance, it is safe.

Inherited from:
IterableFactoryDefaults
Source:
Iterable.scala

Tests whether the collection is not empty.

Tests whether the collection is not empty.

Returns:

true if the collection contains at least one element, false otherwise.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
override def partition(p: A => Boolean): (C, C)

A pair of, first, all elements that satisfy predicate p and, second, all elements that do not.

A pair of, first, all elements that satisfy predicate p and, second, all elements that do not. Interesting because it splits a collection in two.

The default implementation provided here needs to traverse the collection twice. Strict collections have an overridden version of partition in StrictOptimizedIterableOps, which requires only a single traversal.

Definition Classes
Inherited from:
StrictOptimizedIterableOps
Source:
StrictOptimizedIterableOps.scala
override def partitionMap[A1, A2](f: A => Either[A1, A2]): (CC[A1], CC[A2])

Applies a function f to each element of the iterable collection and returns a pair of iterable collections: the first one made of those values returned by f that were wrapped in scala.util.Left, and the second one made of those wrapped in scala.util.Right.

Applies a function f to each element of the iterable collection and returns a pair of iterable collections: the first one made of those values returned by f that were wrapped in scala.util.Left, and the second one made of those wrapped in scala.util.Right.

Example:

val xs = Iterable(1, "one", 2, "two", 3, "three") partitionMap {
 case i: Int => Left(i)
 case s: String => Right(s)
}
// xs == (Iterable(1, 2, 3),
//        Iterable(one, two, three))
Type parameters:
A1

the element type of the first resulting collection

A2

the element type of the second resulting collection

Value parameters:
f

the 'split function' mapping the elements of this iterable collection to an scala.util.Either

Returns:

a pair of iterable collections: the first one made of those values returned by f that were wrapped in scala.util.Left, and the second one made of those wrapped in scala.util.Right.

Definition Classes
Inherited from:
StrictOptimizedIterableOps
Source:
StrictOptimizedIterableOps.scala
def product[B >: A](implicit num: Numeric[B]): B

Multiplies up the elements of this collection.

Multiplies up the elements of this collection.

Note: will not terminate for infinite-sized collections.

Type parameters:
B

the result type of the * operator.

Value parameters:
num

an implicit parameter defining a set of numeric operations which includes the * operator to be used in forming the product.

Returns:

the product of all elements of this collection with respect to the * operator in num.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def reduce[B >: A](op: (B, B) => B): B

Reduces the elements of this collection using the specified associative binary operator.

Reduces the elements of this collection using the specified associative binary operator.

The order in which operations are performed on elements is unspecified and may be nondeterministic.

Type parameters:
B

A type parameter for the binary operator, a supertype of A.

Value parameters:
op

A binary operator that must be associative.

Returns:

The result of applying reduce operator op between all the elements if the collection is nonempty.

Throws:
UnsupportedOperationException

if this collection is empty.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def reduceLeft[B >: A](op: (B, A) => B): B

Applies a binary operator to all elements of this collection, going left to right.

Applies a binary operator to all elements of this collection, 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.

Type parameters:
B

the result type of the binary operator.

Value parameters:
op

the binary operator.

Returns:

the result of inserting op between consecutive elements of this collection, going left to right: op( op( ... op(x1, x2) ..., xn-1), xn) where x1, ..., xn are the elements of this collection.

Throws:
UnsupportedOperationException

if this collection is empty.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def reduceLeftOption[B >: A](op: (B, A) => B): Option[B]

Optionally applies a binary operator to all elements of this collection, going left to right.

Optionally applies a binary operator to all elements of this collection, 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.

Type parameters:
B

the result type of the binary operator.

Value parameters:
op

the binary operator.

Returns:

an option value containing the result of reduceLeft(op) if this collection is nonempty, None otherwise.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def reduceOption[B >: A](op: (B, B) => B): Option[B]

Reduces the elements of this collection, if any, using the specified associative binary operator.

Reduces the elements of this collection, if any, using the specified associative binary operator.

The order in which operations are performed on elements is unspecified and may be nondeterministic.

Type parameters:
B

A type parameter for the binary operator, a supertype of A.

Value parameters:
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, and None otherwise.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def reduceRight[B >: A](op: (A, B) => B): B

Applies a binary operator to all elements of this collection, going right to left.

Applies a binary operator to all elements of this 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.

Type parameters:
B

the result type of the binary operator.

Value parameters:
op

the binary operator.

Returns:

the result of inserting op between consecutive elements of this collection, going right to left: op(x1, op(x2, ..., op(xn-1, xn)...)) where x1, ..., xn are the elements of this collection.

Throws:
UnsupportedOperationException

if this collection is empty.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def reduceRightOption[B >: A](op: (A, B) => B): Option[B]

Optionally applies a binary operator to all elements of this collection, going right to left.

Optionally applies a binary operator to all elements of this 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.

Type parameters:
B

the result type of the binary operator.

Value parameters:
op

the binary operator.

Returns:

an option value containing the result of reduceRight(op) if this collection is nonempty, None otherwise.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def result(): C

Result collection consisting of all elements appended so far.

Result collection consisting of all elements appended so far.

Inherited from:
SetOps
Source:
Set.scala
protected def reversed: Iterable[A]
Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def scan[B >: A](z: B)(op: (B, B) => B): CC[B]

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.

Type parameters:
B

element type of the resulting collection

Value parameters:
op

the associative operator for the scan

z

neutral element for the operator op

Returns:

a new iterable collection containing the prefix scan of the elements in this iterable collection

Inherited from:
IterableOps
Source:
Iterable.scala
override def scanLeft[B](z: B)(op: (B, A) => B): CC[B]

Produces a iterable collection containing cumulative results of applying the operator going left to right, including the initial value.

Produces a iterable collection containing cumulative results of applying the operator going left to right, including the initial value.

Note: will not terminate for infinite-sized collections.

Note: might return different results for different runs, unless the underlying collection type is ordered.

Type parameters:
B

the type of the elements in the resulting collection

Value parameters:
op

the binary operator applied to the intermediate result and the element

z

the initial value

Returns:

collection with intermediate results

Definition Classes
Inherited from:
StrictOptimizedIterableOps
Source:
StrictOptimizedIterableOps.scala
def scanRight[B](z: B)(op: (A, B) => B): CC[B]

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.

Note: Even when applied to a view or a lazy collection it will always force the elements.

Example:

List(1, 2, 3, 4).scanRight(0)(_ + _) == List(10, 9, 7, 4, 0)
Type parameters:
B

the type of the elements in the resulting collection

Value parameters:
op

the binary operator applied to the intermediate result and the element

z

the initial value

Returns:

collection with intermediate results

Inherited from:
IterableOps
Source:
Iterable.scala
def sizeCompare(that: Iterable[_]): Int

Compares the size of this iterable collection to the size of another Iterable.

Compares the size of this iterable collection to the size of another Iterable.

Value parameters:
that

the Iterable whose size is compared with this iterable collection's size.

Returns:

A value x where

x <  0       if this.size <  that.size
x == 0       if this.size == that.size
x >  0       if this.size >  that.size

The method as implemented here does not call size directly; its running time is O(this.size min that.size) instead of O(this.size + that.size). The method should be overridden if computing size is cheap and knownSize returns -1.

Inherited from:
IterableOps
Source:
Iterable.scala
def sizeCompare(otherSize: Int): Int

Compares the size of this iterable collection to a test value.

Compares the size of this iterable collection to a test value.

Value parameters:
otherSize

the test value that gets compared with the size.

Returns:

A value x where

x <  0       if this.size <  otherSize
x == 0       if this.size == otherSize
x >  0       if this.size >  otherSize

The method as implemented here does not call size directly; its running time is O(size min otherSize) instead of O(size). The method should be overridden if computing size is cheap and knownSize returns -1.

See also:
Inherited from:
IterableOps
Source:
Iterable.scala
final def sizeHint(coll: IterableOnce[_], delta: Int): Unit

Gives a hint that one expects the result of this builder to have the same size as the given collection, plus some delta.

Gives a hint that one expects the result of this builder to have the same size as the given collection, plus some delta. This will provide a hint only if the collection has a known size Some builder classes will optimize their representation based on the hint. However, builder implementations are still required to work correctly even if the hint is wrong, i.e. a different number of elements is added.

Value parameters:
coll

the collection which serves as a hint for the result's size.

delta

a correction to add to the coll.size to produce the size hint.

Inherited from:
Builder
Source:
Builder.scala
def sizeHint(size: Int): Unit

Gives a hint how many elements are expected to be added when the next result is called.

Gives a hint how many elements are expected to be added when the next result is called. Some builder classes will optimize their representation based on the hint. However, builder implementations are still required to work correctly even if the hint is wrong, i.e. a different number of elements is added.

Value parameters:
size

the hint how many elements will be added.

Inherited from:
Builder
Source:
Builder.scala
final def sizeHintBounded(size: Int, boundingColl: Iterable[_]): Unit

Gives a hint how many elements are expected to be added when the next result is called, together with an upper bound given by the size of some other collection.

Gives a hint how many elements are expected to be added when the next result is called, together with an upper bound given by the size of some other collection. Some builder classes will optimize their representation based on the hint. However, builder implementations are still required to work correctly even if the hint is wrong, i.e. a different number of elements is added.

Value parameters:
boundingColl

the bounding collection. If it is an IndexedSeqLike, then sizes larger than collection's size are reduced.

size

the hint how many elements will be added.

Inherited from:
Builder
Source:
Builder.scala

Returns a value class containing operations for comparing the size of this iterable collection to a test value.

Returns a value class containing operations for comparing the size of this iterable collection to a test value.

These operations are implemented in terms of sizeCompare(Int), and allow the following more readable usages:

this.sizeIs < size     // this.sizeCompare(size) < 0
this.sizeIs <= size    // this.sizeCompare(size) <= 0
this.sizeIs == size    // this.sizeCompare(size) == 0
this.sizeIs != size    // this.sizeCompare(size) != 0
this.sizeIs >= size    // this.sizeCompare(size) >= 0
this.sizeIs > size     // this.sizeCompare(size) > 0
Inherited from:
IterableOps
Source:
Iterable.scala
def slice(from: Int, until: Int): C

Selects an interval of elements.

Selects an interval of elements. The returned iterable 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.

Value parameters:
from

the lowest index to include from this iterable collection.

until

the lowest index to EXCLUDE from this iterable collection.

Returns:

a iterable collection containing the elements greater than or equal to index from extending up to (but not including) index until of this iterable collection.

Inherited from:
IterableOps
Source:
Iterable.scala
def sliding(size: Int, step: Int): Iterator[C]

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.)

The returned iterator will be empty when called on an empty collection. The last element the iterator produces may be smaller than the window size when the original collection isn't exhausted by the window before it and its last element isn't skipped by the step before it.

Value parameters:
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 smaller if there are fewer than size elements remaining to be grouped.

See also:
Example:

List(1, 2, 3, 4, 5).sliding(2, 2) = Iterator(List(1, 2), List(3, 4), List(5))

List(1, 2, 3, 4, 5, 6).sliding(2, 3) = Iterator(List(1, 2), List(4, 5))

Inherited from:
IterableOps
Source:
Iterable.scala
def sliding(size: Int): Iterator[C]

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.)

An empty collection returns an empty iterator, and a non-empty collection containing fewer elements than the window size returns an iterator that will produce the original collection as its only element.

Value parameters:
size

the number of elements per group

Returns:

An iterator producing iterable collections of size size, except for a non-empty collection with less than size elements, which returns an iterator that produces the source collection itself as its only element.

See also:
Example:

List().sliding(2) = empty iterator

List(1).sliding(2) = Iterator(List(1))

List(1, 2).sliding(2) = Iterator(List(1, 2))

List(1, 2, 3).sliding(2) = Iterator(List(1, 2), List(2, 3))

Inherited from:
IterableOps
Source:
Iterable.scala
override def span(p: A => Boolean): (C, C)

Splits this iterable collection into a prefix/suffix pair according to a predicate.

Splits this iterable 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.

Value parameters:
p

the test predicate

Returns:

a pair consisting of the longest prefix of this iterable collection whose elements all satisfy p, and the rest of this iterable collection.

Definition Classes
Inherited from:
StrictOptimizedIterableOps
Source:
StrictOptimizedIterableOps.scala
override def splitAt(n: Int): (C, C)

Splits this iterable collection into a prefix/suffix pair at a given position.

Splits this iterable collection into a prefix/suffix pair 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.

Value parameters:
n

the position at which to split.

Returns:

a pair of iterable collections consisting of the first n elements of this iterable collection, and the other elements.

Definition Classes
Inherited from:
IterableOps
Source:
Iterable.scala
def stepper[S <: Stepper[_]](implicit shape: StepperShape[A, S]): S

Returns a scala.collection.Stepper for the elements of this collection.

Returns a scala.collection.Stepper for the elements of this collection.

The Stepper enables creating a Java stream to operate on the collection, see scala.jdk.StreamConverters. For collections holding primitive values, the Stepper can be used as an iterator which doesn't box the elements.

The implicit scala.collection.StepperShape parameter defines the resulting Stepper type according to the element type of this collection.

Note that this method is overridden in subclasses and the return type is refined to S with EfficientSplit, for example scala.collection.IndexedSeqOps.stepper. For Steppers marked with scala.collection.Stepper.EfficientSplit, the converters in scala.jdk.StreamConverters allow creating parallel streams, whereas bare Steppers can be converted only to sequential streams.

Inherited from:
IterableOnce
Source:
IterableOnce.scala
def subsetOf(that: Set[A]): Boolean

Tests whether this set is a subset of another set.

Tests whether this set is a subset of another set.

Value parameters:
that

the set to test.

Returns:

true if this set is a subset of that, i.e. if every element of this set is also an element of that.

Inherited from:
SetOps
Source:
Set.scala
def subsets(): Iterator[C]

An iterator over all subsets of this set.

An iterator over all subsets of this set.

Returns:

the iterator.

Inherited from:
SetOps
Source:
Set.scala
def subsets(len: Int): Iterator[C]

An iterator over all subsets of this set of the given size.

An iterator over all subsets of this set of the given size. If the requested size is impossible, an empty iterator is returned.

Value parameters:
len

the size of the subsets.

Returns:

the iterator.

Inherited from:
SetOps
Source:
Set.scala
def subtractAll(xs: IterableOnce[A]): Shrinkable.this.type

Removes all elements produced by an iterator from this shrinkable collection.

Removes all elements produced by an iterator from this shrinkable collection.

Value parameters:
xs

the iterator producing the elements to remove.

Returns:

the shrinkable collection itself

Inherited from:
Shrinkable
Source:
Shrinkable.scala
def sum[B >: A](implicit num: Numeric[B]): B

Sums up the elements of this collection.

Sums up the elements of this collection.

Note: will not terminate for infinite-sized collections.

Type parameters:
B

the result type of the + operator.

Value parameters:
num

an implicit parameter defining a set of numeric operations which includes the + operator to be used in forming the sum.

Returns:

the sum of all elements of this collection with respect to the + operator in num.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def tail: C

The rest of the collection without its first element.

The rest of the collection without its first element.

Inherited from:
IterableOps
Source:
Iterable.scala
def tails: Iterator[C]

Iterates over the tails of this iterable collection.

Iterates over the tails of this iterable collection. The first value will be this iterable collection and the final one will be an empty iterable collection, with the intervening values the results of successive applications of tail.

Returns:

an iterator over all the tails of this iterable collection

Example:

List(1,2,3).tails = Iterator(List(1,2,3), List(2,3), List(3), Nil)

Inherited from:
IterableOps
Source:
Iterable.scala
def take(n: Int): C

Selects the first n elements.

Selects the first n elements.

Note: might return different results for different runs, unless the underlying collection type is ordered.

Value parameters:
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 than n elements. If n is negative, returns an empty iterable collection.

Inherited from:
IterableOps
Source:
Iterable.scala
override def takeRight(n: Int): C

A collection containing the last n elements of this collection.

A collection containing the last n elements of this collection.

Note: Even when applied to a view or a lazy collection it will always force the elements.

Definition Classes
Inherited from:
StrictOptimizedIterableOps
Source:
StrictOptimizedIterableOps.scala
def takeWhile(p: A => Boolean): C

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.

Value parameters:
p

The predicate used to test elements.

Returns:

the longest prefix of this iterable collection whose elements all satisfy the predicate p.

Inherited from:
IterableOps
Source:
Iterable.scala
override def tapEach[U](f: A => U): C

Applies a side-effecting function to each element in this collection.

Applies a side-effecting function to each element in this collection. Strict collections will apply f to their elements immediately, while lazy collections like Views and LazyLists will only apply f on each element if and when that element is evaluated, and each time that element is evaluated.

Type parameters:
U

the return type of f

Value parameters:
f

a function to apply to each element in this iterable collection

Returns:

The same logical collection as this

Definition Classes
Inherited from:
StrictOptimizedIterableOps
Source:
StrictOptimizedIterableOps.scala
def to[C1](factory: Factory[A, C1]): C1

Given a collection factory factory, convert this collection to the appropriate representation for the current element type A.

Given a collection factory factory, convert this collection to the appropriate representation for the current element type A. Example uses:

xs.to(List) xs.to(ArrayBuffer) xs.to(BitSet) // for xs: Iterable[Int]

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def toArray[B >: A : ClassTag]: Array[B]

Convert collection to array.

Convert collection to array.

Implementation note: DO NOT call Array.from from this method.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
final def toBuffer[B >: A]: Buffer[B]
Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def toList: List[A]
Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def toMap[K, V](implicit ev: A <:< (K, V)): Map[K, V]
Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def toSeq: Seq[A]
Returns:

This collection as a Seq[A]. This is equivalent to to(Seq) but might be faster.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def toSet[B >: A]: Set[B]
Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
override def toString(): String

Returns a string representation of the object.

Returns a string representation of the object.

The default representation is platform dependent.

Returns:

a string representation of the object.

Definition Classes
Inherited from:
Set
Source:
Set.scala
def transpose[B](implicit asIterable: A => Iterable[B]): CC[CC[B]]

Transposes this iterable collection of iterable collections into a iterable collection of iterable collections.

Transposes this iterable collection of iterable collections into a iterable collection of iterable collections.

The resulting collection's type will be guided by the static type of iterable 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))

Note: Even when applied to a view or a lazy collection it will always force the elements.

Type parameters:
B

the type of the elements of each iterable collection.

Value parameters:
asIterable

an implicit conversion which asserts that the element type of this iterable collection is an Iterable.

Returns:

a two-dimensional iterable collection of iterable collections which has as nth row the nth column of this iterable collection.

Throws:
IllegalArgumentException

if all collections in this iterable collection are not of the same size.

Inherited from:
IterableOps
Source:
Iterable.scala
final def union(that: Set[A]): C

Computes the union between of set and another set.

Computes the union between of set and another set.

Value parameters:
that

the set to form the union with.

Returns:

a new set consisting of all elements that are in this set or in the given set that.

Inherited from:
SetOps
Source:
Set.scala
override def unzip[A1, A2](implicit asPair: A => (A1, A2)): (CC[A1], CC[A2])

Converts this iterable collection of pairs into two collections of the first and second half of each pair.

Converts this iterable collection of pairs into two collections of the first and second half of each pair.

val xs = Iterable(
           (1, "one"),
           (2, "two"),
           (3, "three")).unzip
// xs == (Iterable(1, 2, 3),
//        Iterable(one, two, three))
Type parameters:
A1

the type of the first half of the element pairs

A2

the type of the second half of the element pairs

Value parameters:
asPair

an implicit conversion which asserts that the element type of this iterable collection is a pair.

Returns:

a pair of iterable collections, containing the first, respectively second half of each element pair of this iterable collection.

Definition Classes
Inherited from:
StrictOptimizedIterableOps
Source:
StrictOptimizedIterableOps.scala
override def unzip3[A1, A2, A3](implicit asTriple: A => (A1, A2, A3)): (CC[A1], CC[A2], CC[A3])

Converts this iterable collection of triples into three collections of the first, second, and third element of each triple.

Converts this iterable collection of triples into three collections of the first, second, and third element of each triple.

val xs = Iterable(
           (1, "one", '1'),
           (2, "two", '2'),
           (3, "three", '3')).unzip3
// xs == (Iterable(1, 2, 3),
//        Iterable(one, two, three),
//        Iterable(1, 2, 3))
Type parameters:
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

Value parameters:
asTriple

an implicit conversion which asserts that the element type of this iterable collection is a triple.

Returns:

a triple of iterable collections, containing the first, second, respectively third member of each element triple of this iterable collection.

Definition Classes
Inherited from:
StrictOptimizedIterableOps
Source:
StrictOptimizedIterableOps.scala
def update(elem: A, included: Boolean): Unit

Updates the presence of a single element in this set.

Updates the presence of a single element in this set.

This method allows one to add or remove an element elem from this set depending on the value of parameter included. Typically, one would use the following syntax:

set(elem) = true  // adds element
set(elem) = false // removes element
Value parameters:
elem

the element to be added or removed

included

a flag indicating whether element should be included or excluded.

Inherited from:
SetOps
Source:
Set.scala
def view: View[A]

A view over the elements of this collection.

A view over the elements of this collection.

Inherited from:
IterableOps
Source:
Iterable.scala
def withFilter(p: A => Boolean): WithFilter[A, CC]

Creates a non-strict filter of this iterable collection.

Creates a non-strict filter of this iterable collection.

Note: the difference between c filter p and c withFilter p is that the former creates a new collection, whereas the latter only restricts the domain of subsequent map, flatMap, foreach, and withFilter operations.

Note: might return different results for different runs, unless the underlying collection type is ordered.

Value parameters:
p

the predicate used to test elements.

Returns:

an object of class WithFilter, which supports map, flatMap, foreach, and withFilter operations. All these operations apply to those elements of this iterable collection which satisfy the predicate p.

Inherited from:
IterableOps
Source:
Iterable.scala
override def zip[B](that: IterableOnce[B]): CC[(A, B)]

Returns a iterable collection formed from this iterable collection and another iterable collection by combining corresponding elements in pairs.

Returns a iterable collection formed from this iterable collection 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.

Type parameters:
B

the type of the second half of the returned pairs

Value parameters:
that

The iterable providing the second half of each result pair

Returns:

a new iterable collection containing pairs consisting of corresponding elements of this iterable collection and that. The length of the returned collection is the minimum of the lengths of this iterable collection and that.

Definition Classes
Inherited from:
StrictOptimizedIterableOps
Source:
StrictOptimizedIterableOps.scala
def zipAll[A1 >: A, B](that: Iterable[B], thisElem: A1, thatElem: B): CC[(A1, B)]

Returns a iterable collection formed from this iterable collection and another iterable collection by combining corresponding elements in pairs.

Returns a iterable collection formed from this iterable collection 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.

Value parameters:
that

the iterable providing the second half of each result pair

thatElem

the element to be used to fill up the result if that is shorter than this iterable collection.

thisElem

the element to be used to fill up the result if this iterable collection is shorter than that.

Returns:

a new collection of type That containing pairs consisting of corresponding elements of this iterable collection and that. The length of the returned collection is the maximum of the lengths of this iterable collection and that. If this iterable collection is shorter than that, thisElem values are used to pad the result. If that is shorter than this iterable collection, thatElem values are used to pad the result.

Inherited from:
IterableOps
Source:
Iterable.scala
override def zipWithIndex: CC[(A, Int)]

Zips this iterable collection with its indices.

Zips this iterable collection with its indices.

Returns:

A new iterable collection containing pairs consisting of all elements of this iterable collection paired with their index. Indices start at 0.

Example:

List("a", "b", "c").zipWithIndex == List(("a", 0), ("b", 1), ("c", 2))

Definition Classes
Inherited from:
StrictOptimizedIterableOps
Source:
StrictOptimizedIterableOps.scala
final def |(that: Set[A]): C

Alias for union

Alias for union

Inherited from:
SetOps
Source:
Set.scala

Deprecated and Inherited methods

def +(elem1: A, elem2: A, elems: A*): C
Deprecated
Inherited from:
SetOps
Source:
Set.scala
def +(elem: A): C
Deprecated
Inherited from:
SetOps
Source:
Set.scala
def ++:[B >: A](that: IterableOnce[B]): CC[B]
Deprecated
Inherited from:
IterableOps
Source:
Iterable.scala
final def +=(elem1: A, elem2: A, elems: A*): Growable.this.type

Adds two or more elements to this growable collection.

Adds two or more elements to this growable collection.

Value parameters:
elem1

the first element to add.

elem2

the second element to add.

elems

the remaining elements to add.

Returns:

the growable collection itself

Deprecated
Inherited from:
Growable
Source:
Growable.scala
def -(elem1: A, elem2: A, elems: A*): C
Deprecated
Inherited from:
SetOps
Source:
Set.scala
def -(elem: A): C
Deprecated
Inherited from:
SetOps
Source:
Set.scala
def --(that: IterableOnce[A]): C
Deprecated
Inherited from:
SetOps
Source:
Set.scala
def -=(elem1: A, elem2: A, elems: A*): Shrinkable.this.type

Removes two or more elements from this shrinkable collection.

Removes two or more elements from this shrinkable collection.

Value parameters:
elem1

the first element to remove.

elem2

the second element to remove.

elems

the remaining elements to remove.

Returns:

the shrinkable collection itself

Deprecated
Inherited from:
Shrinkable
Source:
Shrinkable.scala
final def /:[B](z: B)(op: (B, A) => B): B
Deprecated
Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
final def :\[B](z: B)(op: (A, B) => B): B
Deprecated
Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def aggregate[B](z: => B)(seqop: (B, A) => B, combop: (B, B) => B): B
Deprecated
Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
Deprecated
Inherited from:
IterableOps
Source:
Iterable.scala
final def copyToBuffer[B >: A](dest: Buffer[B]): Unit
Deprecated
Inherited from:
IterableOnceOps
Source:
IterableOnce.scala

Tests whether this collection is known to have a finite size.

Tests whether this 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 returns true if all elements have been computed. It returns false if the stream is not yet evaluated to the end. Non-empty Iterators usually return false 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 returns true. However, checking hasDefiniteSize 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.

See also:

method knownSize for a more useful alternative

Deprecated

This method is deprecated in 2.13 because it does not provide any actionable information. As noted above, even the collection library itself does not use it. When there is no guarantee that a collection is finite, it is generally best to attempt a computation anyway and document that it will not terminate for infinite collections rather than backing out because this would prevent performing the computation on collections that are in fact finite even though hasDefiniteSize returns false.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
final def repr: C
Deprecated
Inherited from:
IterableOps
Source:
Iterable.scala
final def retain(p: A => Boolean): Unit
Deprecated
Inherited from:
SetOps
Source:
Set.scala
def seq: Iterable.this.type
Deprecated
Inherited from:
Iterable
Source:
Iterable.scala
final def toIterable: Iterable.this.type
Returns:

This collection as an Iterable[A]. No new collection will be built if this is already an Iterable[A].

Deprecated
Inherited from:
Iterable
Source:
Iterable.scala
final def toIterator: Iterator[A]
Deprecated
Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
final def toStream: Stream[A]
Deprecated
Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
final def toTraversable: Iterable[A]

Converts this iterable collection to an unspecified Iterable.

Converts this iterable collection to an unspecified Iterable. Will return the same collection if this instance is already Iterable.

Returns:

An Iterable containing all elements of this iterable collection.

Deprecated
Inherited from:
IterableOps
Source:
Iterable.scala
def view(from: Int, until: Int): View[A]

A view over a slice of the elements of this collection.

A view over a slice of the elements of this collection.

Deprecated
Inherited from:
IterableOps
Source:
Iterable.scala