scala.collection

# TraversableOnce

###
Related Docs: object TraversableOnce | package collection

#### trait TraversableOnce[+A] extends GenTraversableOnce[A]

A template trait for collections which can be traversed either once only or one or more times.

This trait exists primarily to eliminate code duplication between `Iterator` and `Traversable`, and thus implements some of the common methods that can be implemented solely in terms of foreach without access to a `Builder`. It also includes a number of abstract methods whose implementations are provided by `Iterator`, `Traversable`, etc. It contains implementations common to `Iterators` and `Traversables`, such as folds, conversions, and other operations which traverse some or all of the elements and return a derived value. Directly subclassing `TraversableOnce` is not recommended - instead, consider declaring an `Iterator` with a `next` and `hasNext` method, creating an `Iterator` with one of the methods on the `Iterator` object, or declaring a subclass of `Traversable`.

Self Type
  TraversableOnce[A]
Source
  TraversableOnce.scala
Version

  2.8

Since

  2.8

Linear Supertypes
GenTraversableOnce[A], Any
Known Subclasses
::, AbstractBuffer, AbstractIterable, AbstractIterable, AbstractIterator, AbstractMap, AbstractMap, AbstractMap, AbstractSeq, AbstractSeq, AbstractSet, AbstractSet, AbstractTraversable, AnyRefMap, Appended, Appended, Appended, Appended, Appended, Appended, ArrayBuffer, ArrayLike, ArrayOps, ArraySeq, ArrayStack, BitSet, BitSet, BitSet, BitSet1, BitSet2, BitSetLike, BitSetN, Buffer, BufferLike, BufferProxy, BufferedIterator, BufferedLineIterator, BufferedSource, Cons, DefaultKeySet, DefaultKeySet, DefaultKeySortedSet, DefaultKeySortedSet, DefaultMap, DefaultMap, DefaultMapModel, DefaultValuesIterable, DoubleLinkedList, DoubleLinkedListLike, DroppedWhile, DroppedWhile, DroppedWhile, DroppedWhile, DroppedWhile, Elements, Elements, Empty, EmptyView, EmptyView, EmptyView, EmptyView, EntryIterator, Exclusive, Filtered, Filtered, Filtered, Filtered, Filtered, FilteredKeys, FilteredKeys, FlatMapped, FlatMapped, FlatMapped, FlatMapped, Forced, Forced, Forced, Forced, GroupedIterator, HashMap, HashMap, HashMap1, HashSet, HashSet, HashTrieMap, HashTrieSet, History, ImmutableDefaultKeySet, ImmutableMapAdaptor, ImmutableSetAdaptor, Impl, Inclusive, Inclusive, IndexedSeq, IndexedSeq, IndexedSeq, IndexedSeqLike, IndexedSeqLike, IndexedSeqOptimized, IndexedSeqOptimized, IndexedSeqView, IntMap, Iterable, Iterable, Iterable, IterableForwarder, IterableLike, IterableProxy, IterableProxyLike, IterableSplitter, IterableView, IterableViewLike, Iterator, LineIterator, LinearSeq, LinearSeq, LinearSeq, LinearSeqLike, LinearSeqOptimized, LinkedHashMap, LinkedHashSet, LinkedList, LinkedListLike, List, ListBuffer, ListMap, ListMap, ListSet, LongMap, LongMap, Map, Map, Map, Map, Map1, Map2, Map3, Map4, MapLike, MapLike, MapLike, MapProxy, MapProxy, MapProxy, MapProxyLike, Mapped, Mapped, Mapped, Mapped, Mapped, Mapped, MappedValues, MappedValues, MatchIterator, MultiMap, MutableList, Nil, Node, Node, NumericRange, ObservableBuffer, ObservableMap, ObservableSet, OpenHashMap, PagedSeq, ParArrayIterator, ParFlatHashTableIterator, ParHashMapIterator, ParHashMapIterator, ParHashSetIterator, ParHashSetIterator, ParRangeIterator, ParVectorIterator, Patched, Patched, Patched, PreciseSplitter, Prepended, Prepended, PriorityQueue, PriorityQueueProxy, Queue, Queue, QueueProxy, Range, ResizableArray, Reversed, Reversed, Reversed, RevertibleHistory, Script, Seq, Seq, Seq, SeqForwarder, SeqLike, SeqLike, SeqProxy, SeqProxyLike, SeqSplitter, SeqView, SeqViewLike, Set, Set, Set, Set1, Set2, Set3, Set4, SetLike, SetLike, SetProxy, SetProxy, SetProxy, SetProxyLike, Sliced, Sliced, Sliced, Sliced, Sliced, SortedMap, SortedMap, SortedMapLike, SortedSet, SortedSet, SortedSet, SortedSetLike, Source, Splitter, Stack, Stack, StackProxy, Stream, StreamIterator, StreamView, StreamViewLike, StringBuilder, StringLike, StringOps, SynchronizedBuffer, SynchronizedMap, SynchronizedPriorityQueue, SynchronizedQueue, SynchronizedSet, SynchronizedStack, SystemProperties, Taken, Taken, TakenWhile, TakenWhile, TakenWhile, TakenWhile, TakenWhile, Transformed, Transformed, Transformed, Transformed, Transformed, Traversable, Traversable, Traversable, TraversableForwarder, TraversableLike, TraversableProxy, TraversableProxyLike, TraversableView, TraversableViewLike, TreeMap, TreeSet, TreeSet, TrieMap, UnrolledBuffer, ValueSet, Vector, VectorIterator, WithDefault, WithDefault, WithDefault, WrappedArray, WrappedString, Zipped, Zipped, Zipped, Zipped, Zipped, ZippedAll, ZippedAll, ZippedAll, ZippedAll, ZippedAll, ofBoolean, ofBoolean, ofByte, ofByte, ofChar, ofChar, ofDouble, ofDouble, ofFloat, ofFloat, ofInt, ofInt, ofLong, ofLong, ofRef, ofRef, ofShort, ofShort, ofUnit, ofUnit
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Inherited

1. TraversableOnce
2. GenTraversableOnce
3. Any

Implicitly

1. by MonadOps
2. by any2stringadd
3. by StringFormat
4. by Ensuring
5. by ArrowAssoc
6. by alternateImplicit

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Visibility

1. Public
2. All

### Abstract Value Members

1. #### abstract def copyToArray[B >: A](xs: Array[B], start: Int, len: Int): Unit

   Definition Classes
     TraversableOnce → GenTraversableOnce

2. #### abstract def exists(p: (A) ⇒ Boolean): Boolean

   Definition Classes
     TraversableOnce → GenTraversableOnce

3. #### abstract def find(p: (A) ⇒ Boolean): Option[A]

   Finds the first element of the traversable or iterator satisfying a predicate, if any.

   Finds the first element of the traversable or iterator satisfying a predicate, if any.

   Note: may not terminate for infinite-sized collections.

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

   returns

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

   Definition Classes
     TraversableOnce → GenTraversableOnce

4. #### abstract def forall(p: (A) ⇒ Boolean): Boolean

   Definition Classes
     TraversableOnce → GenTraversableOnce

5. #### abstract def foreach[U](f: (A) ⇒ U): Unit

   Self-documenting abstract methods.

   Self-documenting abstract methods.

   Definition Classes
     TraversableOnce → GenTraversableOnce

6. #### abstract def getClass(): Class[_]

   Returns the runtime class representation of the object.

   Returns the runtime class representation of the object.

   returns

     a class object corresponding to the runtime type of the receiver.

   Definition Classes
     Any

7. #### abstract def hasDefiniteSize: Boolean

   Definition Classes
     TraversableOnce → GenTraversableOnce

8. #### abstract def isEmpty: Boolean

   Tests whether the traversable or iterator is empty.

   Tests whether the traversable or iterator is empty.

   returns

     `true` if the traversable or iterator contains no elements, `false` otherwise.

   Definition Classes
     TraversableOnce → GenTraversableOnce

9. #### abstract def isTraversableAgain: Boolean

   Tests whether this collection or iterator can be repeatedly traversed.

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

   returns

     `true` if it is repeatedly traversable, `false` otherwise.

   Definition Classes
     GenTraversableOnce

10. #### abstract def seq: TraversableOnce[A]

    A version of this collection with all of the operations implemented sequentially (i.e., in a single-threaded manner).

    A version of this collection with all of the operations implemented sequentially (i.e., in a single-threaded manner).

    This method returns a reference to this collection. In parallel collections, it is redefined to return a sequential implementation of this collection. In both cases, it has O(1) complexity.

    returns

      a sequential view of the collection.

    Definition Classes
      TraversableOnce → GenTraversableOnce

11. #### abstract def toIterator: Iterator[A]

    Returns an Iterator over the elements in this collection or iterator.

    Returns an Iterator over the elements in this collection or iterator. Will return the same Iterator if this instance is already an Iterator.

    Note: will not terminate for infinite-sized collections.

    returns

      an Iterator containing all elements of this collection or iterator.

    Definition Classes
      GenTraversableOnce

12. #### abstract def toStream: Stream[A]

    Converts this collection or iterator to a stream.

    Converts this collection or iterator to a stream.

    returns

      a stream containing all elements of this collection or iterator.

    Definition Classes
      GenTraversableOnce

13. #### abstract def toTraversable: Traversable[A]

    Converts this traversable or iterator to an unspecified Traversable.

    Converts this traversable or iterator to an unspecified Traversable. Will return the same collection if this instance is already Traversable.

    Note: will not terminate for infinite-sized collections.

    returns

      a Traversable containing all elements of this traversable or iterator.

    Definition Classes
      TraversableOnce → GenTraversableOnce

### Concrete Value Members

1. #### final def !=(arg0: Any): Boolean

   Test two objects for inequality.

   Test two objects for inequality.

   returns

     `true` if !(this == that), false otherwise.

   Definition Classes
     Any

2. #### final def ##(): Int

   Equivalent to `x.hashCode` except for boxed numeric types and `null`.

   Equivalent to `x.hashCode` except for boxed numeric types and `null`. For numerics, it returns a hash value which is consistent with value equality: if two value type instances compare as true, then ## will produce the same hash value for each of them. For `null` returns a hashcode where `null.hashCode` throws a `NullPointerException`.

   returns

     a hash value consistent with ==

   Definition Classes
     Any

3. #### def +(other: String): String

   Implicit information
     This member is added by an implicit conversion from TraversableOnce[A] to any2stringadd[TraversableOnce[A]] performed by method any2stringadd in scala.Predef.
   Definition Classes
     any2stringadd

4. #### def ->[B](y: B): (TraversableOnce[A], B)

   Implicit information
     This member is added by an implicit conversion from TraversableOnce[A] to ArrowAssoc[TraversableOnce[A]] performed by method ArrowAssoc in scala.Predef.
   Definition Classes
     ArrowAssoc
   Annotations
     @inline()

5. #### def /:[B](z: B)(op: (B, A) ⇒ B): B

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

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

   Note: `/:` is alternate syntax for `foldLeft`; `z /: xs` is the same as `xs foldLeft z`.

   Examples:

   Note that the folding function used to compute b is equivalent to that used to compute c.

       scala> val a = List(1,2,3,4)
       a: List[Int] = List(1, 2, 3, 4)

       scala> val b = (5 /: a)(_+_)
       b: Int = 15

       scala> val c = (5 /: a)((x,y) => x + y)
       c: Int = 15

   Note: will not terminate for infinite-sized collections.

   Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.

   B

     the result type of the binary operator.

   z

     the start value.

   op

     the binary operator.

   returns

     the result of inserting `op` between consecutive elements of this traversable or iterator, going left to right with the start value `z` on the left:

         op(...op(op(z, x_1), x_2), ..., x_n)

     where `x1, ..., xn` are the elements of this traversable or iterator.

   Definition Classes
     TraversableOnce → GenTraversableOnce

6. #### def :\[B](z: B)(op: (A, B) ⇒ B): B

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

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

   Note: `:\` is alternate syntax for `foldRight`; `xs :\ z` is the same as `xs foldRight z`.

   Note: will not terminate for infinite-sized collections.

   Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.

   Examples:

   Note that the folding function used to compute b is equivalent to that used to compute c.

       scala> val a = List(1,2,3,4)
       a: List[Int] = List(1, 2, 3, 4)

       scala> val b = (a :\ 5)(_+_)
       b: Int = 15

       scala> val c = (a :\ 5)((x,y) => x + y)
       c: Int = 15

   B

     the result type of the binary operator.

   z

     the start value

   op

     the binary operator

   returns

     the result of inserting `op` between consecutive elements of this traversable or iterator, going right to left with the start value `z` on the right:

         op(x_1, op(x_2, ... op(x_n, z)...))

     where `x1, ..., xn` are the elements of this traversable or iterator.

   Definition Classes
     TraversableOnce → GenTraversableOnce

7. #### final def ==(arg0: Any): Boolean

   Test two objects for equality.

   Test two objects for equality. The expression `x == that` is equivalent to `if (x eq null) that eq null else x.equals(that)`.

   returns

     `true` if the receiver object is equivalent to the argument; `false` otherwise.

   Definition Classes
     Any

8. #### def addString(b: StringBuilder): StringBuilder

   Appends all elements of this traversable or iterator to a string builder.

   Appends all elements of this traversable or iterator to a string builder. The written text consists of the string representations (w.r.t. the method `toString`) of all elements of this traversable or iterator without any separator string.

   Example:

       scala> val a = List(1,2,3,4)
       a: List[Int] = List(1, 2, 3, 4)

       scala> val b = new StringBuilder()
       b: StringBuilder =

       scala> val h = a.addString(b)
       h: StringBuilder = 1234

   b

     the string builder to which elements are appended.

   returns

     the string builder `b` to which elements were appended.

9. #### def addString(b: StringBuilder, sep: String): StringBuilder

   Appends all elements of this traversable or iterator to a string builder using a separator string.

   Appends all elements of this traversable or iterator to a string builder using a separator string. The written text consists of the string representations (w.r.t. the method `toString`) of all elements of this traversable or iterator, separated by the 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

   b

     the string builder to which elements are appended.

   sep

     the separator string.

   returns

     the string builder `b` to which elements were appended.

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

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

    Appends all elements of this traversable or iterator to a string builder using start, end, and separator strings. The written text begins with the string `start` and ends with the string `end`. Inside, the string representations (w.r.t. the method `toString`) of all elements of this traversable or iterator 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)

    b

      the string builder to which elements are appended.

    start

      the starting string.

    sep

      the separator string.

    end

      the ending string.

    returns

      the string builder `b` to which elements were appended.

11. #### def aggregate[B](z: ⇒ B)(seqop: (B, A) ⇒ B, combop: (B, B) ⇒ B): B

    Aggregates the results of applying an operator to subsequent elements.

    Aggregates the results of applying an operator to subsequent elements.

    This is a more general form of `fold` and `reduce`. It has similar semantics, but does not require the result to be a supertype of the element type. It traverses the elements in different partitions sequentially, using `seqop` to update the result, and then applies `combop` to results from different partitions. The implementation of this operation may operate on an arbitrary number of collection partitions, so `combop` may be invoked an arbitrary number of times.

    For example, one might want to process some elements and then produce a `Set`. In this case, `seqop` would process an element and append it to the list, while `combop` would concatenate two lists from different partitions together. The initial value `z` would be an empty set.

        pc.aggregate(Set[Int]())(_ += process(_), _ ++ _)

    Another example is calculating geometric mean from a collection of doubles (one would typically require big doubles for this).

    B

      the type of accumulated results

    z

      the initial value for the accumulated result of the partition - this will typically be the neutral element for the `seqop` operator (e.g. `Nil` for list concatenation or `0` for summation) and may be evaluated more than once

    seqop

      an operator used to accumulate results within a partition

    combop

      an associative operator used to combine results from different partitions

    Definition Classes
      TraversableOnce → GenTraversableOnce

12. #### final def asInstanceOf[T0]: T0

    Cast the receiver object to be of type `T0`.

    Cast the receiver object to be of type `T0`.

    Note that the success of a cast at runtime is modulo Scala's erasure semantics. Therefore the expression `1.asInstanceOf[String]` will throw a `ClassCastException` at runtime, while the expression `List(1).asInstanceOf[List[String]]` will not. In the latter example, because the type argument is erased as part of compilation it is not possible to check whether the contents of the list are of the requested type.

    returns

      the receiver object.

    Definition Classes
      Any
    Exceptions thrown

      `ClassCastException` if the receiver object is not an instance of the erasure of type `T0`.

13. #### def collectFirst[B](pf: PartialFunction[A, B]): Option[B]

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

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

    Note: may not terminate for infinite-sized collections.

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

    pf

      the partial function

    returns

      an option value containing pf applied to the first value for which it is defined, or `None` if none exists.

    Example:

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

14. #### def copyToArray(xs: Array[A]): Unit

    [use case] Copies values of this traversable or iterator to an array.

    [use case]

    Copies values of this traversable or iterator to an array. Fills the given array `xs` with values of this traversable or iterator. Copying will stop once either the end of the current traversable or iterator is reached, or the end of the array is reached.

    Note: will not terminate for infinite-sized collections.

    xs

      the array to fill.

    Definition Classes
      TraversableOnce → GenTraversableOnce
    Full Signature

    #### def copyToArray[B >: A](xs: Array[B]): Unit

15. #### def copyToArray(xs: Array[A], start: Int): Unit

    [use case] Copies values of this traversable or iterator to an array.

    [use case]

    Copies values of this traversable or iterator to an array. Fills the given array `xs` with values of this traversable or iterator, beginning at index `start`. Copying will stop once either the end of the current traversable or iterator is reached, or the end of the array is reached.

    Note: will not terminate for infinite-sized collections.

    xs

      the array to fill.

    start

      the starting index.

    Definition Classes
      TraversableOnce → GenTraversableOnce
    Full Signature

    #### def copyToArray[B >: A](xs: Array[B], start: Int): Unit

16. #### def copyToBuffer[B >: A](dest: Buffer[B]): Unit

    Copies all elements of this traversable or iterator to a buffer.

    Copies all elements of this traversable or iterator to a buffer.

    Note: will not terminate for infinite-sized collections.

    dest

      The buffer to which elements are copied.

17. #### def count(p: (A) ⇒ Boolean): Int

    Counts the number of elements in the traversable or iterator which satisfy a predicate.

    Counts the number of elements in the traversable or iterator which satisfy a predicate.

    p

      the predicate used to test elements.

    returns

      the number of elements satisfying the predicate `p`.

    Definition Classes
      TraversableOnce → GenTraversableOnce

18. #### def ensuring(cond: (TraversableOnce[A]) ⇒ Boolean, msg: ⇒ Any): TraversableOnce[A]

    Implicit information
      This member is added by an implicit conversion from TraversableOnce[A] to Ensuring[TraversableOnce[A]] performed by method Ensuring in scala.Predef.
    Definition Classes
      Ensuring

19. #### def ensuring(cond: (TraversableOnce[A]) ⇒ Boolean): TraversableOnce[A]

    Implicit information
      This member is added by an implicit conversion from TraversableOnce[A] to Ensuring[TraversableOnce[A]] performed by method Ensuring in scala.Predef.
    Definition Classes
      Ensuring

20. #### def ensuring(cond: Boolean, msg: ⇒ Any): TraversableOnce[A]

    Implicit information
      This member is added by an implicit conversion from TraversableOnce[A] to Ensuring[TraversableOnce[A]] performed by method Ensuring in scala.Predef.
    Definition Classes
      Ensuring

21. #### def ensuring(cond: Boolean): TraversableOnce[A]

    Implicit information
      This member is added by an implicit conversion from TraversableOnce[A] to Ensuring[TraversableOnce[A]] performed by method Ensuring in scala.Predef.
    Definition Classes
      Ensuring

22. #### def equals(arg0: Any): Boolean

    Compares the receiver object (`this`) with the argument object (`that`) for equivalence.

    Compares the receiver object (`this`) with the argument object (`that`) for equivalence.

    Any implementation of this method should be an equivalence relation:

    - It is reflexive: for any instance `x` of type `Any`, `x.equals(x)` should return `true`.
    - It is symmetric: for any instances `x` and `y` of type `Any`, `x.equals(y)` should return `true` if and only if `y.equals(x)` returns `true`.
    - It is transitive: for any instances `x`, `y`, and `z` of type `AnyRef` if `x.equals(y)` returns `true` and `y.equals(z)` returns `true`, then `x.equals(z)` should return `true`.

    If you override this method, you should verify that your implementation remains an equivalence relation. Additionally, when overriding this method it is usually necessary to override `hashCode` to ensure that objects which are "equal" (`o1.equals(o2)` returns `true`) hash to the same scala.Int. (`o1.hashCode.equals(o2.hashCode)`).

    returns

      `true` if the receiver object is equivalent to the argument; `false` otherwise.

    Definition Classes
      Any

23. #### def filter(p: (A) ⇒ Boolean): TraversableOnce[A]

    Implicit information
      This member is added by an implicit conversion from TraversableOnce[A] to MonadOps[A] performed by method MonadOps in scala.collection.TraversableOnce.
    Definition Classes
      MonadOps

24. #### def flatMap[B](f: (A) ⇒ GenTraversableOnce[B]): TraversableOnce[B]

    Implicit information
      This member is added by an implicit conversion from TraversableOnce[A] to MonadOps[A] performed by method MonadOps in scala.collection.TraversableOnce.
    Definition Classes
      MonadOps

25. #### def fold[A1 >: A](z: A1)(op: (A1, A1) ⇒ A1): A1

    Folds the elements of this traversable or iterator using the specified associative binary operator.

    Folds the elements of this traversable or iterator using the specified associative binary operator.

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

    A1

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

    z

      a neutral element for the fold operation; may be added to the result an arbitrary number of times, and must not change the result (e.g., `Nil` for list concatenation, 0 for addition, or 1 for multiplication.)

    op

      a binary operator that must be associative

    returns

      the result of applying fold operator `op` between all the elements and `z`

    Definition Classes
      TraversableOnce → GenTraversableOnce

26. #### def foldLeft[B](z: B)(op: (B, A) ⇒ B): B

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

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

    Note: will not terminate for infinite-sized collections.

    Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.

    B

      the result type of the binary operator.

    z

      the start value.

    op

      the binary operator.

    returns

      the result of inserting `op` between consecutive elements of this traversable or iterator, going left to right with the start value `z` on the left:

          op(...op(z, x_1), x_2, ..., x_n)

      where `x1, ..., xn` are the elements of this traversable or iterator.

    Definition Classes
      TraversableOnce → GenTraversableOnce

27. #### def foldRight[B](z: B)(op: (A, B) ⇒ B): B

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

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

    Note: will not terminate for infinite-sized collections.

    Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.

    B

      the result type of the binary operator.

    z

      the start value.

    op

      the binary operator.

    returns

      the result of inserting `op` between consecutive elements of this traversable or iterator, going right to left with the start value `z` on the right:

          op(x_1, op(x_2, ... op(x_n, z)...))

      where `x1, ..., xn` are the elements of this traversable or iterator.

    Definition Classes
      TraversableOnce → GenTraversableOnce

28. #### def formatted(fmtstr: String): String

    Returns string formatted according to given `format` string.

    Returns string formatted according to given `format` string. Format strings are as for `String.format` (@see java.lang.String.format).

    Implicit information
      This member is added by an implicit conversion from TraversableOnce[A] to StringFormat[TraversableOnce[A]] performed by method StringFormat in scala.Predef.
    Definition Classes
      StringFormat
    Annotations
      @inline()

29. #### def hashCode(): Int

    Calculate a hash code value for the object.

    Calculate a hash code value for the object.

    The default hashing algorithm is platform dependent.

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

    returns

      the hash code value for this object.

    Definition Classes
      Any

30. #### final def isInstanceOf[T0]: Boolean

    Test whether the dynamic type of the receiver object is `T0`.

    Test whether the dynamic type of the receiver object is `T0`.

    Note that the result of the test is modulo Scala's erasure semantics. Therefore the expression `1.isInstanceOf[String]` will return `false`, while the expression `List(1).isInstanceOf[List[String]]` will return `true`. In the latter example, because the type argument is erased as part of compilation it is not possible to check whether the contents of the list are of the specified type.

    returns

      `true` if the receiver object is an instance of erasure of type `T0`; `false` otherwise.

    Definition Classes
      Any

31. #### def map[B](f: (A) ⇒ B): TraversableOnce[B]

    Implicit information
      This member is added by an implicit conversion from TraversableOnce[A] to MonadOps[A] performed by method MonadOps in scala.collection.TraversableOnce.
    Definition Classes
      MonadOps

32. #### def max: A

    [use case] Finds the largest element.

    [use case]

    Finds the largest element.

    returns

      the largest element of this traversable or iterator.

    Definition Classes
      TraversableOnce → GenTraversableOnce
    Full Signature

    #### def max[B >: A](implicit cmp: Ordering[B]): A

33. #### def maxBy[B](f: (A) ⇒ B): A

    [use case] Finds the first element which yields the largest value measured by function f.

    [use case]

    Finds the first element which yields the largest value measured by function f.

    B

      The result type of the function f.

    f

      The measuring function.

    returns

      the first element of this traversable or iterator with the largest value measured by function f.

    Definition Classes
      TraversableOnce → GenTraversableOnce
    Full Signature

    #### def maxBy[B](f: (A) ⇒ B)(implicit cmp: Ordering[B]): A

34. #### def min: A

    [use case] Finds the smallest element.

    [use case]

    Finds the smallest element.

    returns

      the smallest element of this traversable or iterator

    Definition Classes
      TraversableOnce → GenTraversableOnce
    Full Signature

    #### def min[B >: A](implicit cmp: Ordering[B]): A

35. #### def minBy[B](f: (A) ⇒ B): A

    [use case] Finds the first element which yields the smallest value measured by function f.

    [use case]

    Finds the first element which yields the smallest value measured by function f.

    B

      The result type of the function f.

    f

      The measuring function.

    returns

      the first element of this traversable or iterator with the smallest value measured by function f.

    Definition Classes
      TraversableOnce → GenTraversableOnce
    Full Signature

    #### def minBy[B](f: (A) ⇒ B)(implicit cmp: Ordering[B]): A

36. #### def mkString: String

    Displays all elements of this traversable or iterator in a string.

    Displays all elements of this traversable or iterator in a string.

    returns

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

    Definition Classes
      TraversableOnce → GenTraversableOnce

37. #### def mkString(sep: String): String

    Displays all elements of this traversable or iterator in a string using a separator string.

    Displays all elements of this traversable or iterator in a string using a separator string.

    sep

      the separator string.

    returns

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

    Definition Classes
      TraversableOnce → GenTraversableOnce
    Example:

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

38. #### def mkString(start: String, sep: String, end: String): String

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

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

    start

      the starting string.

    sep

      the separator string.

    end

      the ending string.

    returns

      a string representation of this traversable or iterator. The resulting string begins with the string `start` and ends with the string `end`. Inside, the string representations (w.r.t. the method `toString`) of all elements of this traversable or iterator are separated by the string `sep`.

    Definition Classes
      TraversableOnce → GenTraversableOnce
    Example:

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

39. #### def nonEmpty: Boolean

    Tests whether the traversable or iterator is not empty.

    Tests whether the traversable or iterator is not empty.

    returns

      `true` if the traversable or iterator contains at least one element, `false` otherwise.

    Definition Classes
      TraversableOnce → GenTraversableOnce

40. #### def product: A

    [use case] Multiplies up the elements of this collection.

    [use case]

    Multiplies up the elements of this collection.

    returns

      the product of all elements in this traversable or iterator of numbers of type `Int`. Instead of `Int`, any other type `T` with an implicit `Numeric[T]` implementation can be used as element type of the traversable or iterator and as result type of `product`. Examples of such types are: `Long`, `Float`, `Double`, `BigInt`.

    Definition Classes
      TraversableOnce → GenTraversableOnce
    Full Signature

    #### def product[B >: A](implicit num: Numeric[B]): B

41. #### def reduce[A1 >: A](op: (A1, A1) ⇒ A1): A1

    Reduces the elements of this traversable or iterator using the specified associative binary operator.

    Reduces the elements of this traversable or iterator using the specified associative binary operator.

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

    A1

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

    op

      A binary operator that must be associative.

    returns

      The result of applying reduce operator `op` between all the elements if the traversable or iterator is nonempty.

    Definition Classes
      TraversableOnce → GenTraversableOnce
    Exceptions thrown

      `UnsupportedOperationException` if this traversable or iterator is empty.

42. #### def reduceLeft[B >: A](op: (B, A) ⇒ B): B

    Applies a binary operator to all elements of this traversable or iterator, going left to right.

    Applies a binary operator to all elements of this traversable or iterator, going left to right.

    Note: will not terminate for infinite-sized collections.

    Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.

    B

      the result type of the binary operator.

    op

      the binary operator.

    returns

      the result of inserting `op` between consecutive elements of this traversable or iterator, going left to right:

          op( op( ... op(x_1, x_2) ..., x_{n-1}), x_n)

      where `x1, ..., xn` are the elements of this traversable or iterator.

    Exceptions thrown

      `UnsupportedOperationException` if this traversable or iterator is empty.

43. #### def reduceLeftOption[B >: A](op: (B, A) ⇒ B): Option[B]

    Optionally applies a binary operator to all elements of this traversable or iterator, going left to right.

    Optionally applies a binary operator to all elements of this traversable or iterator, going left to right.

    Note: will not terminate for infinite-sized collections.

    Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.

    B

      the result type of the binary operator.

    op

      the binary operator.

    returns

      an option value containing the result of `reduceLeft(op)` if this traversable or iterator is nonempty, `None` otherwise.

    Definition Classes
      TraversableOnce → GenTraversableOnce

44. #### def reduceOption[A1 >: A](op: (A1, A1) ⇒ A1): Option[A1]

    Reduces the elements of this traversable or iterator, if any, using the specified associative binary operator.

    Reduces the elements of this traversable or iterator, if any, using the specified associative binary operator.

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

    A1

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

    op

      A binary operator that must be associative.

    returns

      An option value containing result of applying reduce operator `op` between all the elements if the collection is nonempty, and `None` otherwise.

    Definition Classes
      TraversableOnce → GenTraversableOnce

45. #### def reduceRight[B >: A](op: (A, B) ⇒ B): B

    Applies a binary operator to all elements of this traversable or iterator, going right to left.

    Applies a binary operator to all elements of this traversable or iterator, going right to left.

    Note: will not terminate for infinite-sized collections.

    Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.

    B

      the result type of the binary operator.

    op

      the binary operator.

    returns

      the result of inserting `op` between consecutive elements of this traversable or iterator, going right to left:

          op(x_1, op(x_2, ..., op(x_{n-1}, x_n)...))

      where `x1, ..., xn` are the elements of this traversable or iterator.

    Definition Classes
      TraversableOnce → GenTraversableOnce
    Exceptions thrown

      `UnsupportedOperationException` if this traversable or iterator is empty.

46. #### def reduceRightOption[B >: A](op: (A, B) ⇒ B): Option[B]

    Optionally applies a binary operator to all elements of this traversable or iterator, going right to left.

    Optionally applies a binary operator to all elements of this traversable or iterator, going right to left.

    Note: will not terminate for infinite-sized collections.

    Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.

    B

      the result type of the binary operator.

    op

      the binary operator.

    returns

      an option value containing the result of `reduceRight(op)` if this traversable or iterator is nonempty, `None` otherwise.

    Definition Classes
      TraversableOnce → GenTraversableOnce

47. #### def reversed: List[A]

    Attributes
      protected[this]

48. #### def size: Int

    The size of this traversable or iterator.

    The size of this traversable or iterator.

    Note: will not terminate for infinite-sized collections.

    returns

      the number of elements in this traversable or iterator.

    Definition Classes
      TraversableOnce → GenTraversableOnce

49. #### def sum: A

    [use case] Sums up the elements of this collection.

    [use case]

    Sums up the elements of this collection.

    returns

      the sum of all elements in this traversable or iterator of numbers of type `Int`. Instead of `Int`, any other type `T` with an implicit `Numeric[T]` implementation can be used as element type of the traversable or iterator and as result type of `sum`. Examples of such types are: `Long`, `Float`, `Double`, `BigInt`.

    Definition Classes
      TraversableOnce → GenTraversableOnce
    Full Signature

    #### def sum[B >: A](implicit num: Numeric[B]): B

50. #### def to[Col[_]]: Col[A]

    [use case] Converts this traversable or iterator into another by copying all elements.

    [use case]

    Converts this traversable or iterator into another by copying all elements.

    Note: will not terminate for infinite-sized collections.

    Col

      The collection type to build.

    returns

      a new collection containing all elements of this traversable or iterator.

    Definition Classes
      TraversableOnce → GenTraversableOnce
    Full Signature

    #### def to[Col[_]](implicit cbf: CanBuildFrom[Nothing, A, Col[A]]): Col[A]

51. #### def toArray: Array[A]

    [use case] Converts this traversable or iterator to an array.

    [use case]

    Converts this traversable or iterator to an array.

    Note: will not terminate for infinite-sized collections.

    returns

      an array containing all elements of this traversable or iterator. An `ClassTag` must be available for the element type of this traversable or iterator.

    Definition Classes
      TraversableOnce → GenTraversableOnce
    Full Signature

    #### def toArray[B >: A](implicit arg0: ClassTag[B]): Array[B]

52. #### def toBuffer[B >: A]: Buffer[B]

    Uses the contents of this traversable or iterator to create a new mutable buffer.

    Uses the contents of this traversable or iterator to create a new mutable buffer.

    Note: will not terminate for infinite-sized collections.

    returns

      a buffer containing all elements of this traversable or iterator.

    Definition Classes
      TraversableOnce → GenTraversableOnce

53. #### def toIndexedSeq: immutable.IndexedSeq[A]

    Converts this traversable or iterator to an indexed sequence.

    Converts this traversable or iterator to an indexed sequence.

    Note: will not terminate for infinite-sized collections.

    returns

      an indexed sequence containing all elements of this traversable or iterator.

    Definition Classes
      TraversableOnce → GenTraversableOnce

54. #### def toIterable: Iterable[A]

    Converts this traversable or iterator to an iterable collection.

    Converts this traversable or iterator to an iterable collection. Note that the choice of target `Iterable` is lazy in this default implementation as this `TraversableOnce` may be lazy and unevaluated (i.e. it may be an iterator which is only traversable once).

    Note: will not terminate for infinite-sized collections.

    returns

      an `Iterable` containing all elements of this traversable or iterator.

    Definition Classes
      TraversableOnce → GenTraversableOnce

55. #### def toList: List[A]

    Converts this traversable or iterator to a list.

    Converts this traversable or iterator to a list.

    Note: will not terminate for infinite-sized collections.

    returns

      a list containing all elements of this traversable or iterator.

    Definition Classes
      TraversableOnce → GenTraversableOnce

56. #### def toMap[T, U]: Map[T, U]

    [use case] Converts this traversable or iterator to a map.

    [use case]

    Converts this traversable or iterator to a map. This method is unavailable unless the elements are members of Tuple2, each ((T, U)) becoming a key-value pair in the map. Duplicate keys will be overwritten by later keys: if this is an unordered collection, which key is in the resulting map is undefined.

    Note: will not terminate for infinite-sized collections.

    returns

      a map of type `immutable.Map[T, U]` containing all key/value pairs of type `(T, U)` of this traversable or iterator.

    Definition Classes
      TraversableOnce → GenTraversableOnce
    Full Signature

    #### def toMap[T, U](implicit ev: <:<[A, (T, U)]): immutable.Map[T, U]

57. #### def toSeq: Seq[A]

    Converts this traversable or iterator to a sequence.

    Converts this traversable or iterator to a sequence. As with `toIterable`, it's lazy in this default implementation, as this `TraversableOnce` may be lazy and unevaluated.

    Note: will not terminate for infinite-sized collections.

    returns

      a sequence containing all elements of this traversable or iterator.

    Definition Classes
      TraversableOnce → GenTraversableOnce

58. #### def toSet[B >: A]: immutable.Set[B]

    Converts this traversable or iterator to a set.

    Converts this traversable or iterator to a set.

    Note: will not terminate for infinite-sized collections.

    returns

      a set containing all elements of this traversable or iterator.

    Definition Classes
      TraversableOnce → GenTraversableOnce

59. #### def toString(): String

    Returns a string representation of the object.

    Returns a string representation of the object.

    The default representation is platform dependent.

    returns

      a string representation of the object.

    Definition Classes
      Any

60. #### def toVector: Vector[A]

    Converts this traversable or iterator to a Vector.

    Converts this traversable or iterator to a Vector.

    Note: will not terminate for infinite-sized collections.

    returns

      a vector containing all elements of this traversable or iterator.

    Definition Classes
      TraversableOnce → GenTraversableOnce

61. #### def withFilter(p: (A) ⇒ Boolean): Iterator[A]

    Implicit information
      This member is added by an implicit conversion from TraversableOnce[A] to MonadOps[A] performed by method MonadOps in scala.collection.TraversableOnce.
    Definition Classes
      MonadOps

62. #### def →[B](y: B): (TraversableOnce[A], B)

    Implicit information
      This member is added by an implicit conversion from TraversableOnce[A] to ArrowAssoc[TraversableOnce[A]] performed by method ArrowAssoc in scala.Predef.
    Definition Classes
      ArrowAssoc

### Inherited from GenTraversableOnce[A]

### Inherited from Any

### Inherited by implicit conversion MonadOps from TraversableOnce[A] to MonadOps[A]

### Inherited by implicit conversion any2stringadd from TraversableOnce[A] to any2stringadd[TraversableOnce[A]]

### Inherited by implicit conversion StringFormat from TraversableOnce[A] to StringFormat[TraversableOnce[A]]

### Inherited by implicit conversion Ensuring from TraversableOnce[A] to Ensuring[TraversableOnce[A]]

### Inherited by implicit conversion ArrowAssoc from TraversableOnce[A] to ArrowAssoc[TraversableOnce[A]]

### Inherited by implicit conversion alternateImplicit from TraversableOnce[A] to ForceImplicitAmbiguity

### Ungrouped