Scala 3/scala.collection/IterableOnceOps

IterableOnceOps

trait IterableOnceOps[+A, +CC[_], +C]

This implementation trait can be mixed into an IterableOnce to get the basic methods that are shared between Iterator and Iterable. The IterableOnce must support multiple calls to iterator but may or may not return the same Iterator every time.

Source:
IterableOnce.scala
class Any
trait IterableOps[A, CC, C]
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]
trait Iterator[A]
class Source

Value members

Abstract methods

def collect[B](pf: PartialFunction[A, B]): CC[B]

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

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

Type parameters:
B

the element type of the returned collection.

Value parameters:
pf

the partial function which filters and maps the collection.

Returns:

a new 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:
IterableOnce.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 collection.

Returns:

a collection consisting of all elements of this collection except the first n ones, or else the empty collection, if this collection has less than n elements. If n is negative, don't drop any elements.

Source:
IterableOnce.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 collection whose first element does not satisfy the predicate p.

Source:
IterableOnce.scala
def filter(p: A => Boolean): C

Selects all elements of this collection which satisfy a predicate.

Selects all elements of this collection which satisfy a predicate.

Value parameters:
p

the predicate used to test elements.

Returns:

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

Source:
IterableOnce.scala
def filterNot(pred: A => Boolean): C

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

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

Value parameters:
pred

the predicate used to test elements.

Returns:

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

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

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

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

Source:
IterableOnce.scala
def flatten[B](implicit asIterable: A => IterableOnce[B]): CC[B]

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

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

The resulting collection's type will be guided by the type of 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 collection is a GenTraversable.

Returns:

a new collection resulting from concatenating all element collections.

Source:
IterableOnce.scala
def map[B](f: A => B): CC[B]

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

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

Type parameters:
B

the element type of the returned collection.

Value parameters:
f

the function to apply to each element.

Returns:

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

Source:
IterableOnce.scala
def scanLeft[B](z: B)(op: (B, A) => B): CC[B]

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

Produces a 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:
IterableOnce.scala
def slice(from: Int, until: Int): C

Selects an interval of elements.

Selects an interval of elements. The returned collection is made up of all elements x which satisfy the invariant:

from <= indexOf(x) < until

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

Value parameters:
from

the lowest index to include from this collection.

until

the lowest index to EXCLUDE from this collection.

Returns:

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

Source:
IterableOnce.scala
def span(p: A => Boolean): (C, C)

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

Splits this 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 collection whose elements all satisfy p, and the rest of this collection.

Source:
IterableOnce.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 collection.

Returns:

a collection consisting only of the first n elements of this collection, or else the whole collection, if it has less than n elements. If n is negative, returns an empty collection.

Source:
IterableOnce.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 collection whose elements all satisfy the predicate p.

Source:
IterableOnce.scala
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 collection

Returns:

The same logical collection as this

Source:
IterableOnce.scala
def zipWithIndex: CC[(A, Int)]

Zips this collection with its indices.

Zips this collection with its indices.

Returns:

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

Example:

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

Source:
IterableOnce.scala

Concrete methods

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.

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.

Source:
IterableOnce.scala
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.

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)

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.

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.

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.

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

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.

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

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.

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.

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.

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.

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.

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.

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.

Source:
IterableOnce.scala
def isTraversableAgain: Boolean

Tests whether this collection can be repeatedly traversed.

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

Returns:

true if it is repeatedly traversable, false otherwise.

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.

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.

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.

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.

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.

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.

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.

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.

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)"

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"

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.

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.

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.

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.

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.

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.

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.

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.

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.

Source:
IterableOnce.scala
protected def reversed: Iterable[A]
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.

Source:
IterableOnce.scala
def splitAt(n: Int): (C, C)

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

Splits this 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 collections consisting of the first n elements of this collection, and the other elements.

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.

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]

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.

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

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

Source:
IterableOnce.scala
def toSet[B >: A]: Set[B]

Deprecated methods

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

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