trait IterableOnceOps[+A, +CC[_], +C] extends Any
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.
- Self Type
- IterableOnceOps[A, CC, C] with IterableOnce[A]
- Source
- IterableOnce.scala
- Alphabetic
- By Inheritance
- IterableOnceOps
- Any
- by any2stringadd
- by StringFormat
- by Ensuring
- by ArrowAssoc
- Hide All
- Show All
- Public
- All
Abstract Value Members
-
abstract
def
collect[B](pf: PartialFunction[A, B]): CC[B]
Builds a new $coll by applying a partial function to all elements of this $coll on which the function is defined.
Builds a new $coll by applying a partial function to all elements of this $coll on which the function is defined.
- B
the element type of the returned $coll.
- pf
the partial function which filters and maps the $coll.
- returns
a new $coll 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.
- Note
Reuse: $consumesAndProducesIterator
-
abstract
def
drop(n: Int): C
Selects all elements except first n ones.
Selects all elements except first n ones. $orderDependent
- n
the number of elements to drop from this $coll.
- returns
a $coll consisting of all elements of this $coll except the first
n
ones, or else the empty $coll, if this $coll has less thann
elements. Ifn
is negative, don't drop any elements.
- Note
Reuse: $consumesAndProducesIterator
-
abstract
def
dropWhile(p: (A) ⇒ Boolean): C
Drops longest prefix of elements that satisfy a predicate.
Drops longest prefix of elements that satisfy a predicate. $orderDependent
- p
The predicate used to test elements.
- returns
the longest suffix of this $coll whose first element does not satisfy the predicate
p
.
- Note
Reuse: $consumesAndProducesIterator
-
abstract
def
filter(p: (A) ⇒ Boolean): C
Selects all elements of this $coll which satisfy a predicate.
Selects all elements of this $coll which satisfy a predicate.
- p
the predicate used to test elements.
- returns
a new iterator consisting of all elements of this $coll that satisfy the given predicate
p
. The order of the elements is preserved.
-
abstract
def
filterNot(pred: (A) ⇒ Boolean): C
Selects all elements of this $coll which do not satisfy a predicate.
Selects all elements of this $coll which do not satisfy a predicate.
- pred
the predicate used to test elements.
- returns
a new $coll consisting of all elements of this $coll that do not satisfy the given predicate
pred
. Their order may not be preserved.
-
abstract
def
flatMap[B](f: (A) ⇒ IterableOnce[B]): CC[B]
Builds a new $coll by applying a function to all elements of this $coll and using the elements of the resulting collections.
Builds a new $coll by applying a function to all elements of this $coll 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 $coll. This might cause unexpected results sometimes. For example:
// lettersOf will return a Seq[Char] of likely repeated letters, instead of a Set def lettersOf(words: Seq[String]) = words flatMap (word => word.toSet) // lettersOf will return a Set[Char], not a Seq def lettersOf(words: Seq[String]) = words.toSet flatMap (word => word.toSeq) // xs will be an Iterable[Int] val xs = Map("a" -> List(11,111), "b" -> List(22,222)).flatMap(_._2) // ys will be a Map[Int, Int] val ys = Map("a" -> List(1 -> 11,1 -> 111), "b" -> List(2 -> 22,2 -> 222)).flatMap(_._2)
- B
the element type of the returned collection.
- f
the function to apply to each element.
- returns
a new $coll resulting from applying the given collection-valued function
f
to each element of this $coll and concatenating the results.
- Note
Reuse: $consumesAndProducesIterator
-
abstract
def
flatten[B](implicit asIterable: (A) ⇒ IterableOnce[B]): CC[B]
Converts this $coll of traversable collections into a $coll formed by the elements of these traversable collections.
Converts this $coll of traversable collections into a $coll formed by the elements of these traversable collections.
The resulting collection's type will be guided by the type of $coll. 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)
- B
the type of the elements of each traversable collection.
- asIterable
an implicit conversion which asserts that the element type of this $coll is a
GenTraversable
.- returns
a new $coll resulting from concatenating all element ${coll}s.
- Note
Reuse: $consumesAndProducesIterator
-
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
-
abstract
def
map[B](f: (A) ⇒ B): CC[B]
Builds a new $coll by applying a function to all elements of this $coll.
Builds a new $coll by applying a function to all elements of this $coll.
- B
the element type of the returned $coll.
- f
the function to apply to each element.
- returns
a new $coll resulting from applying the given function
f
to each element of this $coll and collecting the results.
- Note
Reuse: $consumesAndProducesIterator
-
abstract
def
scanLeft[B](z: B)(op: (B, A) ⇒ B): CC[B]
Produces a $coll containing cumulative results of applying the operator going left to right, including the initial value.
Produces a $coll containing cumulative results of applying the operator going left to right, including the initial value.
$willNotTerminateInf $orderDependent
- B
the type of the elements in the resulting collection
- z
the initial value
- op
the binary operator applied to the intermediate result and the element
- returns
collection with intermediate results
- Note
Reuse: $consumesAndProducesIterator
-
abstract
def
slice(from: Int, until: Int): C
Selects an interval of elements.
Selects an interval of elements. The returned $coll is made up of all elements
x
which satisfy the invariant:from <= indexOf(x) < until
$orderDependent
- from
the lowest index to include from this $coll.
- until
the lowest index to EXCLUDE from this $coll.
- returns
a $coll containing the elements greater than or equal to index
from
extending up to (but not including) indexuntil
of this $coll.
- Note
Reuse: $consumesAndProducesIterator
-
abstract
def
span(p: (A) ⇒ Boolean): (C, C)
Splits this $coll into a prefix/suffix pair according to a predicate.
Splits this $coll 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 predicatep
does not cause any side-effects. $orderDependent- p
the test predicate
- returns
a pair consisting of the longest prefix of this $coll whose elements all satisfy
p
, and the rest of this $coll.
- Note
Reuse: $consumesOneAndProducesTwoIterators
-
abstract
def
take(n: Int): C
Selects first n elements.
Selects first n elements. $orderDependent
- n
the number of elements to take from this $coll.
- returns
a $coll consisting only of the first
n
elements of this $coll, or else the whole $coll, if it has less thann
elements. Ifn
is negative, returns an empty $coll.
- Note
Reuse: $consumesAndProducesIterator
-
abstract
def
takeWhile(p: (A) ⇒ Boolean): C
Takes longest prefix of elements that satisfy a predicate.
Takes longest prefix of elements that satisfy a predicate. $orderDependent
- p
The predicate used to test elements.
- returns
the longest prefix of this $coll whose elements all satisfy the predicate
p
.
- Note
Reuse: $consumesAndProducesIterator
-
abstract
def
zipWithIndex: CC[(A, Int)]
Zips this $coll with its indices.
Zips this $coll with its indices.
- returns
A new $coll containing pairs consisting of all elements of this $coll paired with their index. Indices start at
0
.
List("a", "b", "c").zipWithIndex == List(("a", 0), ("b", 1), ("c", 2))
- Note
Reuse: $consumesAndProducesIterator
Example:
Concrete Value Members
-
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
-
final
def
##(): Int
Equivalent to
x.hashCode
except for boxed numeric types andnull
.Equivalent to
x.hashCode
except for boxed numeric types andnull
. 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. Fornull
returns a hashcode wherenull.hashCode
throws aNullPointerException
.- returns
a hash value consistent with ==
- Definition Classes
- Any
-
def
+(other: String): String
- Implicit
- This member is added by an implicit conversion from IterableOnceOps[A, CC, C] to any2stringadd[IterableOnceOps[A, CC, C]] performed by method any2stringadd in scala.Predef.
- Definition Classes
- any2stringadd
-
def
->[B](y: B): (IterableOnceOps[A, CC, C], B)
- Implicit
- This member is added by an implicit conversion from IterableOnceOps[A, CC, C] to ArrowAssoc[IterableOnceOps[A, CC, C]] performed by method ArrowAssoc in scala.Predef.
- Definition Classes
- ArrowAssoc
- Annotations
- @inline()
-
final
def
==(arg0: Any): Boolean
Test two objects for equality.
Test two objects for equality. The expression
x == that
is equivalent toif (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
-
def
addString(b: mutable.StringBuilder): mutable.StringBuilder
Appends all elements of this $coll to a string builder.
Appends all elements of this $coll to a string builder. The written text consists of the string representations (w.r.t. the method
toString
) of all elements of this $coll 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.
-
def
addString(b: mutable.StringBuilder, sep: String): mutable.StringBuilder
Appends all elements of this $coll to a string builder using a separator string.
Appends all elements of this $coll 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 $coll, separated by the stringsep
.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.
-
def
addString(b: mutable.StringBuilder, start: String, sep: String, end: String): b.type
Appends all elements of this $coll to a string builder using start, end, and separator strings.
Appends all elements of this $coll to a string builder using start, end, and separator strings. The written text begins with the string
start
and ends with the stringend
. Inside, the string representations (w.r.t. the methodtoString
) of all elements of this $coll are separated by the stringsep
.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.
-
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 aClassCastException
at runtime, while the expressionList(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 typeT0
.
-
def
collectFirst[B](pf: PartialFunction[A, B]): Option[B]
Finds the first element of the $coll for which the given partial function is defined, and applies the partial function to it.
Finds the first element of the $coll for which the given partial function is defined, and applies the partial function to it.
$mayNotTerminateInf $orderDependent
- 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.
Seq("a", 1, 5L).collectFirst({ case x: Int => x*10 }) = Some(10)
Example: -
def
copyToArray(xs: Array[A], start: Int, len: Int): Unit
[use case] $willNotTerminateInf
-
def
copyToArray(xs: Array[A], start: Int): Unit
[use case] $willNotTerminateInf
-
def
count(p: (A) ⇒ Boolean): Int
Counts the number of elements in the $coll which satisfy a predicate.
Counts the number of elements in the $coll which satisfy a predicate.
- p
the predicate used to test elements.
- returns
the number of elements satisfying the predicate
p
.
-
def
ensuring(cond: (IterableOnceOps[A, CC, C]) ⇒ Boolean, msg: ⇒ Any): IterableOnceOps[A, CC, C]
- Implicit
- This member is added by an implicit conversion from IterableOnceOps[A, CC, C] to Ensuring[IterableOnceOps[A, CC, C]] performed by method Ensuring in scala.Predef.
- Definition Classes
- Ensuring
-
def
ensuring(cond: (IterableOnceOps[A, CC, C]) ⇒ Boolean): IterableOnceOps[A, CC, C]
- Implicit
- This member is added by an implicit conversion from IterableOnceOps[A, CC, C] to Ensuring[IterableOnceOps[A, CC, C]] performed by method Ensuring in scala.Predef.
- Definition Classes
- Ensuring
-
def
ensuring(cond: Boolean, msg: ⇒ Any): IterableOnceOps[A, CC, C]
- Implicit
- This member is added by an implicit conversion from IterableOnceOps[A, CC, C] to Ensuring[IterableOnceOps[A, CC, C]] performed by method Ensuring in scala.Predef.
- Definition Classes
- Ensuring
-
def
ensuring(cond: Boolean): IterableOnceOps[A, CC, C]
- Implicit
- This member is added by an implicit conversion from IterableOnceOps[A, CC, C] to Ensuring[IterableOnceOps[A, CC, C]] performed by method Ensuring in scala.Predef.
- Definition Classes
- Ensuring
-
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 typeAny
,x.equals(x)
should returntrue
. - It is symmetric: for any instances
x
andy
of typeAny
,x.equals(y)
should returntrue
if and only ify.equals(x)
returnstrue
. - It is transitive: for any instances
x
,y
, andz
of typeAny
ifx.equals(y)
returnstrue
andy.equals(z)
returnstrue
, thenx.equals(z)
should returntrue
.
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)
returnstrue
) 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
- It is reflexive: for any instance
-
def
exists(p: (A) ⇒ Boolean): Boolean
Tests whether a predicate holds for at least one element of this $coll.
Tests whether a predicate holds for at least one element of this $coll.
$mayNotTerminateInf
- p
the predicate used to test elements.
- returns
true
if the given predicatep
is satisfied by at least one element of this $coll, otherwisefalse
-
def
find(p: (A) ⇒ Boolean): Option[A]
Finds the first element of the $coll satisfying a predicate, if any.
Finds the first element of the $coll satisfying a predicate, if any.
$mayNotTerminateInf $orderDependent
- p
the predicate used to test elements.
- returns
an option value containing the first element in the $coll that satisfies
p
, orNone
if none exists.
-
def
foldLeft[B](z: B)(op: (B, A) ⇒ B): B
Applies a binary operator to a start value and all elements of this $coll, going left to right.
Applies a binary operator to a start value and all elements of this $coll, going left to right.
$willNotTerminateInf $orderDependentFold
- 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 $coll, going left to right with the start valuez
on the left:op(...op(z, x_1), x_2, ..., x_n)
where
x1, ..., xn
are the elements of this $coll. Returnsz
if this $coll is empty.
-
def
foldRight[B](z: B)(op: (A, B) ⇒ B): B
Applies a binary operator to all elements of this $coll and a start value, going right to left.
Applies a binary operator to all elements of this $coll and a start value, going right to left.
$willNotTerminateInf $orderDependentFold
- 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 $coll, going right to left with the start valuez
on the right:op(x_1, op(x_2, ... op(x_n, z)...))
where
x1, ..., xn
are the elements of this $coll. Returnsz
if this $coll is empty.
-
def
forall(p: (A) ⇒ Boolean): Boolean
Tests whether a predicate holds for all elements of this $coll.
Tests whether a predicate holds for all elements of this $coll.
$mayNotTerminateInf
- p
the predicate used to test elements.
- returns
true
if this $coll is empty or the given predicatep
holds for all elements of this $coll, otherwisefalse
.
-
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. -
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 forString.format
(@see java.lang.String.format).- Implicit
- This member is added by an implicit conversion from IterableOnceOps[A, CC, C] to StringFormat[IterableOnceOps[A, CC, C]] performed by method StringFormat in scala.Predef.
- Definition Classes
- StringFormat
- Annotations
- @inline()
-
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)
returnsfalse
). A degenerate implementation could always return0
. However, it is required that if two objects are equal (o1.equals(o2)
returnstrue
) 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 theequals
method.- returns
the hash code value for this object.
- Definition Classes
- Any
-
def
isEmpty: Boolean
Tests whether the $coll is empty.
Tests whether the $coll 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 $coll contains no elements,false
otherwise.
-
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 returnfalse
, while the expressionList(1).isInstanceOf[List[String]]
will returntrue
. 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 typeT0
;false
otherwise.
- Definition Classes
- Any
-
def
knownSize: Int
The number of elements in this $coll, if it can be cheaply computed, -1 otherwise.
The number of elements in this $coll, if it can be cheaply computed, -1 otherwise. Cheaply usually means: Not requiring a collection traversal.
-
def
max: A
[use case] Finds the largest element.
[use case]Finds the largest element.
- returns
the largest element of this $coll.
- Exceptions thrown
UnsupportedOperationException
if this $coll is empty.
Full Signaturedef max[B >: A](implicit ord: math.Ordering[B]): A
-
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 $coll with the largest value measured by function f.
- Exceptions thrown
UnsupportedOperationException
if this $coll is empty.
Full Signaturedef maxBy[B](f: (A) ⇒ B)(implicit cmp: math.Ordering[B]): A
-
def
min: A
[use case] Finds the smallest element.
[use case]Finds the smallest element.
- returns
the smallest element of this $coll
- Exceptions thrown
UnsupportedOperationException
if this $coll is empty.
Full Signaturedef min[B >: A](implicit ord: math.Ordering[B]): A
-
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 $coll with the smallest value measured by function f.
- Exceptions thrown
UnsupportedOperationException
if this $coll is empty.
Full Signaturedef minBy[B](f: (A) ⇒ B)(implicit cmp: math.Ordering[B]): A
-
def
mkString: String
Displays all elements of this $coll in a string.
Displays all elements of this $coll in a string.
- returns
a string representation of this $coll. In the resulting string the string representations (w.r.t. the method
toString
) of all elements of this $coll follow each other without any separator string.
-
def
mkString(sep: String): String
Displays all elements of this $coll in a string using a separator string.
Displays all elements of this $coll in a string using a separator string.
- sep
the separator string.
- returns
a string representation of this $coll. In the resulting string the string representations (w.r.t. the method
toString
) of all elements of this $coll are separated by the stringsep
.
List(1, 2, 3).mkString("|") = "1|2|3"
Example: -
def
mkString(start: String, sep: String, end: String): String
Displays all elements of this $coll in a string using start, end, and separator strings.
Displays all elements of this $coll 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 $coll. The resulting string begins with the string
start
and ends with the stringend
. Inside, the string representations (w.r.t. the methodtoString
) of all elements of this $coll are separated by the stringsep
.
List(1, 2, 3).mkString("(", "; ", ")") = "(1; 2; 3)"
Example: -
def
nonEmpty: Boolean
Tests whether the $coll is not empty.
Tests whether the $coll is not empty.
- returns
true
if the $coll contains at least one element,false
otherwise.
- Annotations
- @deprecatedOverriding( message = ... , since = "2.13.0" )
-
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 $coll of numbers of type
Int
. Instead ofInt
, any other typeT
with an implicitNumeric[T]
implementation can be used as element type of the $coll and as result type ofproduct
. Examples of such types are:Long
,Float
,Double
,BigInt
.
Full Signaturedef product[B >: A](implicit num: math.Numeric[B]): B
-
def
reduce[B >: A](op: (B, B) ⇒ B): B
Reduces the elements of this $coll using the specified associative binary operator.
Reduces the elements of this $coll using the specified associative binary operator.
$undefinedorder
- B
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 $coll is nonempty.
- Exceptions thrown
UnsupportedOperationException
if this $coll is empty.
-
def
reduceLeft[B >: A](op: (B, A) ⇒ B): B
Applies a binary operator to all elements of this $coll, going left to right.
Applies a binary operator to all elements of this $coll, going left to right. $willNotTerminateInf $orderDependentFold
- B
the result type of the binary operator.
- op
the binary operator.
- returns
the result of inserting
op
between consecutive elements of this $coll, going left to right:op( op( ... op(x_1, x_2) ..., x_{n-1}), x_n)
where
x1, ..., xn
are the elements of this $coll.
- Exceptions thrown
UnsupportedOperationException
if this $coll is empty.
-
def
reduceLeftOption[B >: A](op: (B, A) ⇒ B): Option[B]
Optionally applies a binary operator to all elements of this $coll, going left to right.
Optionally applies a binary operator to all elements of this $coll, going left to right. $willNotTerminateInf $orderDependentFold
- B
the result type of the binary operator.
- op
the binary operator.
- returns
an option value containing the result of
reduceLeft(op)
if this $coll is nonempty,None
otherwise.
-
def
reduceOption[B >: A](op: (B, B) ⇒ B): Option[B]
Reduces the elements of this $coll, if any, using the specified associative binary operator.
Reduces the elements of this $coll, if any, using the specified associative binary operator.
$undefinedorder
- B
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, andNone
otherwise.
-
def
reduceRight[B >: A](op: (A, B) ⇒ B): B
Applies a binary operator to all elements of this $coll, going right to left.
Applies a binary operator to all elements of this $coll, going right to left. $willNotTerminateInf $orderDependentFold
- B
the result type of the binary operator.
- op
the binary operator.
- returns
the result of inserting
op
between consecutive elements of this $coll, going right to left:op(x_1, op(x_2, ..., op(x_{n-1}, x_n)...))
where
x1, ..., xn
are the elements of this $coll.
- Exceptions thrown
UnsupportedOperationException
if this $coll is empty.
-
def
reduceRightOption[B >: A](op: (A, B) ⇒ B): Option[B]
Optionally applies a binary operator to all elements of this $coll, going right to left.
Optionally applies a binary operator to all elements of this $coll, going right to left. $willNotTerminateInf $orderDependentFold
- B
the result type of the binary operator.
- op
the binary operator.
- returns
an option value containing the result of
reduceRight(op)
if this $coll is nonempty,None
otherwise.
-
def
reversed: Iterable[A]
- Attributes
- protected[this]
-
def
size: Int
The size of this $coll.
The size of this $coll.
$willNotTerminateInf
- returns
the number of elements in this $coll.
-
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 $coll of numbers of type
Int
. Instead ofInt
, any other typeT
with an implicitNumeric[T]
implementation can be used as element type of the $coll and as result type ofsum
. Examples of such types are:Long
,Float
,Double
,BigInt
.
Full Signaturedef sum[B >: A](implicit num: math.Numeric[B]): B
-
def
to[C1](factory: Factory[A, C1]): C1
Given a collection factory
factory
, convert this collection to the appropriate representation for the current element typeA
.Given a collection factory
factory
, convert this collection to the appropriate representation for the current element typeA
. Example uses:xs.to(List) xs.to(ArrayBuffer) xs.to(BitSet) // for xs: Iterable[Int]
-
def
toArray[B >: A](implicit arg0: ClassTag[B]): Array[B]
Convert collection to array.
- def toIndexedSeq: immutable.IndexedSeq[A]
- def toList: immutable.List[A]
- def toMap[K, V](implicit ev: <:<[A, (K, V)]): immutable.Map[K, V]
-
def
toSeq: immutable.Seq[A]
- returns
This collection as a
Seq[A]
. This is equivalent toto(Seq)
but might be faster.
- def toSet[B >: A]: immutable.Set[B]
-
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
- def toVector: immutable.Vector[A]
-
def
→[B](y: B): (IterableOnceOps[A, CC, C], B)
- Implicit
- This member is added by an implicit conversion from IterableOnceOps[A, CC, C] to ArrowAssoc[IterableOnceOps[A, CC, C]] performed by method ArrowAssoc in scala.Predef.
- Definition Classes
- ArrowAssoc
Deprecated Value Members
-
final
def
/:[B](z: B)(op: (B, A) ⇒ B): B
- Annotations
- @deprecated @inline()
- Deprecated
(Since version 2.13.0) Use foldLeft instead of /:
-
final
def
:\[B](z: B)(op: (A, B) ⇒ B): B
- Annotations
- @deprecated @inline()
- Deprecated
(Since version 2.13.0) Use foldRight instead of :\
-
final
def
toBuffer[B >: A]: Buffer[B]
- Annotations
- @deprecated @inline()
- Deprecated
(Since version 2.13.0) Use ArrayBuffer.from(it) instead of it.toBuffer
-
final
def
toIterator: Iterator[A]
- Annotations
- @deprecated @inline()
- Deprecated
(Since version 2.13.0) Use .iterator() instead of .toIterator
-
final
def
toStream: immutable.Stream[A]
- Annotations
- @deprecated @inline()
- Deprecated
(Since version 2.13.0) Use Stream.from(it) instead of it.toStream
This is the documentation for the Scala standard library.
Package structure
The scala package contains core types like
Int
,Float
,Array
orOption
which are accessible in all Scala compilation units without explicit qualification or imports.Notable packages include:
scala.collection
and its sub-packages contain Scala's collections frameworkscala.collection.immutable
- Immutable, sequential data-structures such asVector
,List
,Range
,HashMap
orHashSet
scala.collection.mutable
- Mutable, sequential data-structures such asArrayBuffer
,StringBuilder
,HashMap
orHashSet
scala.collection.concurrent
- Mutable, concurrent data-structures such asTrieMap
scala.concurrent
- Primitives for concurrent programming such asFutures
andPromises
scala.io
- Input and output operationsscala.math
- Basic math functions and additional numeric types likeBigInt
andBigDecimal
scala.sys
- Interaction with other processes and the operating systemscala.util.matching
- Regular expressionsOther packages exist. See the complete list on the right.
Additional parts of the standard library are shipped as separate libraries. These include:
scala.reflect
- Scala's reflection API (scala-reflect.jar)scala.xml
- XML parsing, manipulation, and serialization (scala-xml.jar)scala.collection.parallel
- Parallel collections (scala-parallel-collections.jar)scala.util.parsing
- Parser combinators (scala-parser-combinators.jar)scala.swing
- A convenient wrapper around Java's GUI framework called Swing (scala-swing.jar)Automatic imports
Identifiers in the scala package and the
scala.Predef
object are always in scope by default.Some of these identifiers are type aliases provided as shortcuts to commonly used classes. For example,
List
is an alias forscala.collection.immutable.List
.Other aliases refer to classes provided by the underlying platform. For example, on the JVM,
String
is an alias forjava.lang.String
.