Scala 3/scala.collection/IterableOps

IterableOps

trait IterableOps[+A, +CC[_], +C] extends IterableOnce[A] with IterableOnceOps[A, CC, C]

Base trait for Iterable operations

VarianceNote

We require that for all child classes of Iterable the variance of the child class and the variance of the C parameter passed to IterableOps are the same. We cannot express this since we lack variance polymorphism. That's why we have to resort at some places to write C[A @uncheckedVariance].

Type parameters:
C

type of the collection (e.g. List[Int], String, BitSet). Operations returning a collection with the same type of element (e.g. drop, filter) return a C.

CC

type constructor of the collection (e.g. List, Set). Operations returning a collection with a different type of element B (e.g. map) return a CC[B].

Companion:
object
Source:
Iterable.scala
trait IterableOnceOps[A, CC, C]
trait IterableOnce[A]
class Any
class ArraySeq[A]
class ofBoolean
class ofByte
class ofChar
class ofDouble
class ofFloat
class ofInt
class ofLong
class ofRef[T]
class ofShort
class ofUnit
trait Iterable[A]
class AbstractMap[K, V]
class AbstractMap[K, V]
class HashMap[K, V]
class IntMap[T]
class ListMap[K, V]
class LongMap[T]
class Map1[K, V]
class Map2[K, V]
class Map3[K, V]
class Map4[K, V]
class WithDefault[K, V]
class WithDefault[K, V]
class TreeMap[K, V]
class TreeSeqMap[K, V]
class VectorMap[K, V]
class AbstractMap[K, V]
class TrieMap[K, V]
class AnyRefMap[K, V]
class HashMap[K, V]
class LinkedHashMap[K, V]
class ListMap[K, V]
class LongMap[V]
class WithDefault[K, V]
class WithDefault[K, V]
class OpenHashMap[Key, Value]
class TreeMap[K, V]
class AbstractSeq[A]
class AbstractSeq[A]
class LazyList[A]
class List[A]
class ::[A]
object Nil.type
class NumericRange[T]
class Exclusive[T]
class Inclusive[T]
class Queue[A]
class Range
class Exclusive
class Inclusive
class Stream[A]
class Cons[A]
object Empty.type
class Vector[A]
class AbstractSeq[A]
class ArrayBuffer[A]
class ArrayDeque[A]
class Queue[A]
class Stack[A]
class ListBuffer[A]
class ArraySeq[T]
class ofBoolean
class ofByte
class ofChar
class ofDouble
class ofFloat
class ofInt
class ofLong
class ofRef[T]
class ofShort
class ofUnit
class AbstractSet[A]
class AbstractSet[A]
class ValueSet
class BitSet
class BitSet1
class BitSet2
class BitSetN
class HashSet[A]
class ListSet[A]
class Set1[A]
class Set2[A]
class Set3[A]
class Set4[A]
class TreeSet[A]
class AbstractSet[A]
class BitSet
class HashSet[A]
class LinkedHashSet[A]
class TreeSet[A]
class AbstractView[A]
class AbstractMapView[K, V]
class Filter[K, V]
class FilterKeys[K, V]
class Id[K, V]
class MapValues[K, V, W]
class TapEach[K, V, U]
class Slice[A]
class Id[A]
class Id[A]
class Reverse[A]
class Reverse[A]
class Appended[A]
class Appended[A]
class Appended[A]
class Collect[A, B]
class Concat[A]
class Concat[A]
class Concat[A]
class DistinctBy[A, B]
class Drop[A]
class Drop[A]
class Drop[A]
class DropRight[A]
class DropRight[A]
class DropRight[A]
class DropWhile[A]
class Elems[A]
object Empty.type
class Fill[A]
class Filter[A]
class FlatMap[A, B]
class Iterate[A]
class LeftPartitionMapped[A, A1, A2]
class Map[A, B]
class Map[A, B]
class Map[A, B]
class PadTo[A]
class Prepended[A]
class Prepended[A]
class Prepended[A]
class RightPartitionMapped[A, A1, A2]
class ScanLeft[A, B]
class Single[A]
class Tabulate[A]
class Take[A]
class Take[A]
class Take[A]
class TakeRight[A]
class TakeRight[A]
class TakeRight[A]
class TakeWhile[A]
class Unfold[A, S]
class Updated[A]
class Zip[A, B]
class ZipAll[A, B]
class ZipWithIndex[A]
class PriorityQueue[A]
trait Map[K, V]
trait DefaultMap[K, V]
trait SeqMap[K, V]
trait SeqMap[K, V]
trait SeqMap[K, V]
trait SortedMap[K, V]
trait SortedMap[K, V]
trait SortedMap[K, V]
trait Map[K, V]
trait Map[K, V]
trait Map[K, V]
trait MultiMap[K, V]
trait Seq[A]
trait IndexedSeq[A]
trait IndexedSeq[A]
trait IndexedSeq[T]
trait IndexedBuffer[A]
trait LinearSeq[A]
trait LinearSeq[A]
trait Seq[A]
trait Seq[A]
trait Buffer[A]
class Accumulator[A, CC, C]
trait Set[A]
trait SortedSet[A]
trait BitSet
trait SortedSet[A]
trait SortedSet[A]
trait Set[A]
trait Set[A]
trait View[A]
trait MapView[K, V]
trait SeqView[A]
class Sorted[A, B]
trait Iterable[A]
trait Iterable[A]
trait MapFactoryDefaults[K, V, CC, WithFilterCC]
class WeakHashMap[K, V]
trait MapOps[K, V, CC, C]
trait SortedMapFactoryDefaults[K, V, CC, WithFilterCC, UnsortedCC]
trait SortedMapOps[K, V, CC, C]
trait StrictOptimizedSortedMapOps[K, V, CC, C]
trait StrictOptimizedSortedMapOps[K, V, CC, C]
trait SortedMapOps[K, V, CC, C]
trait SortedMapOps[K, V, CC, C]
trait StrictOptimizedMapOps[K, V, CC, C]
trait StrictOptimizedMapOps[K, V, CC, C]
trait MapOps[K, V, CC, C]
trait MapOps[K, V, CC, C]
trait SeqOps[A, CC, C]
trait IndexedSeqOps[A, CC, C]
trait IndexedSeqOps[A, CC, C]
trait IndexedSeqOps[A, CC, C]
trait LinearSeqOps[A, CC, C]
trait LinearSeqOps[A, CC, C]
trait StrictOptimizedSeqOps[A, CC, C]
trait StrictOptimizedSeqOps[A, CC, C]
trait ArrayDequeOps[A, CC, C]
trait SeqOps[A, CC, C]
trait SeqOps[A, CC, C]
trait SetOps[A, CC, C]
trait SortedSetOps[A, CC, C]
trait BitSetOps[C]
trait SortedSetFactoryDefaults[A, CC, WithFilterCC]
trait SortedSetOps[A, CC, C]
trait SortedSetOps[A, CC, C]
trait StrictOptimizedSetOps[A, CC, C]
trait StrictOptimizedSetOps[A, CC, C]
trait SetOps[A, CC, C]
trait SetOps[A, CC, C]

Value members

Abstract methods

def iterableFactory: IterableFactory[CC]

The companion object of this iterable collection, providing various factory methods.

The companion object of this iterable collection, 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).

Source:
Iterable.scala

Concrete methods

final def ++[B >: A](suffix: IterableOnce[B]): CC[B]

Alias for concat

Alias for concat

Source:
Iterable.scala
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.

Source:
Iterable.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.

Source:
Iterable.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.

Source:
Iterable.scala
def dropRight(n: Int): C

Selects all elements except last n ones.

Selects all elements except last n ones.

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

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 last 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.

Source:
Iterable.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.

Source:
Iterable.scala
def empty: C

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.

Source:
Iterable.scala
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.

Source:
Iterable.scala
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.

Source:
Iterable.scala
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.

Source:
Iterable.scala
def flatten[B](implicit asIterable: 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.

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.

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

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.

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:
Source:
Iterable.scala
def head: A

Selects the first element of this iterable collection.

Selects the first element of this iterable collection.

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

Returns:

the first element of this iterable collection.

Throws:
NoSuchElementException

if the iterable collection is empty.

Source:
Iterable.scala
def headOption: Option[A]

Optionally selects the first element.

Optionally selects the first element.

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

Returns:

the first element of this iterable collection if it is nonempty, None if it is empty.

Source:
Iterable.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.

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)

Source:
Iterable.scala
override def isTraversableAgain: Boolean

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
Source:
Iterable.scala
def last: A

Selects the last element.

Selects the last element.

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

Returns:

The last element of this iterable collection.

Throws:
NoSuchElementException

If the iterable collection is empty.

Source:
Iterable.scala
def lastOption: Option[A]

Optionally selects the last element.

Optionally selects the last element.

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

Returns:

the last element of this iterable collection$ if it is nonempty, None if it is empty.

Source:
Iterable.scala
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.

Source:
Iterable.scala
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.

Source:
Iterable.scala
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.

Source:
Iterable.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

Source:
Iterable.scala
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

Source:
Iterable.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

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:
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.

Source:
Iterable.scala
final def sizeIs: SizeCompareOps

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
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.

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))

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))

Source:
Iterable.scala
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.

Source:
Iterable.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
Source:
Iterable.scala
def tail: C

The rest of the collection without its first element.

The rest of the collection without its first element.

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)

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.

Source:
Iterable.scala
def takeRight(n: Int): C

Selects the last n elements.

Selects the last 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 last 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.

Source:
Iterable.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.

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
Source:
Iterable.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.

Source:
Iterable.scala
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.

Source:
Iterable.scala
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.

Source:
Iterable.scala
def view: View[A]

A view over the elements of this collection.

A view over the elements of this collection.

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.

Source:
Iterable.scala
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.

Source:
Iterable.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.

Source:
Iterable.scala
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))

Source:
Iterable.scala

Deprecated methods

def ++:[B >: A](that: IterableOnce[B]): CC[B]
Deprecated
Source:
Iterable.scala
def companion: IterableFactory[CC]
Deprecated
Source:
Iterable.scala
final def repr: C
Deprecated
Source:
Iterable.scala
def toIterable: Iterable[A]
Returns:

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

Deprecated
Source:
Iterable.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
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
Source:
Iterable.scala

Inherited methods

final def addString(b: StringBuilder): StringBuilder

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
final def addString(b: StringBuilder, sep: String): StringBuilder

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
def addString(b: StringBuilder, start: String, sep: String, end: String): StringBuilder

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 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 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 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
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
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
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.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def isEmpty: Boolean

Tests whether the collection is empty.

Tests whether the collection 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 collection contains no elements, false otherwise.

Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def iterator: Iterator[A]

Iterator can be used only once

Iterator can be used only once

Inherited from:
IterableOnce
Source:
IterableOnce.scala
def knownSize: Int
Returns:

The number of elements in this collection, if it can be cheaply computed, -1 otherwise. Cheaply usually means: Not requiring a collection traversal.

Inherited from:
IterableOnce
Source:
IterableOnce.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
def nonEmpty: Boolean

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
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
protected def reversed: Iterable[A]
Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def size: Int

The size of this collection.

The size of this collection.

Note: will not terminate for infinite-sized collections.

Returns:

the number of elements in this collection.

Inherited from:
IterableOnceOps
Source:
IterableOnce.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 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 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

Deprecated and Inherited methods

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
final def copyToBuffer[B >: A](dest: Buffer[B]): Unit
Deprecated
Inherited from:
IterableOnceOps
Source:
IterableOnce.scala
def hasDefiniteSize: Boolean

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