trait GenTraversableOnce[+A] extends Any
A template trait for all traversable-once objects which may be traversed in parallel.
Methods in this trait are either abstract or can be implemented in terms of other methods.
- Source
- GenTraversableOnce.scala
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- By Inheritance
- GenTraversableOnce
- Any
- by any2stringadd
- by StringFormat
- by Ensuring
- by ArrowAssoc
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Abstract Value Members
-
abstract
def
/:[B](z: B)(op: (B, A) ⇒ B): B
Applies a binary operator to a start value and all elements of this collection or iterator, going left to right.
Applies a binary operator to a start value and all elements of this collection or iterator, going left to right.
Note:
/:
is alternate syntax forfoldLeft
;z /: xs
is the same asxs 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 collection or iterator, going left to right with the start valuez
on the left:op(...op(op(z, x_1), x_2), ..., x_n)
where
x1, ..., xn
are the elements of this collection or iterator.
-
abstract
def
:\[B](z: B)(op: (A, B) ⇒ B): B
Applies a binary operator to all elements of this collection or iterator and a start value, going right to left.
Applies a binary operator to all elements of this collection or iterator and a start value, going right to left.
Note:
:\
is alternate syntax forfoldRight
;xs :\ z
is the same asxs 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 collection or iterator, 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 collection or iterator.
-
abstract
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
andreduce
. It is similar tofoldLeft
in that it doesn't require the result to be a supertype of the element type. In addition, it allows parallel collections to be processed in chunks, and then combines the intermediate results.aggregate
splits the collection or iterator into partitions and processes each partition by sequentially applyingseqop
, starting withz
(likefoldLeft
). Those intermediate results are then combined by usingcombop
(likefold
). The implementation of this operation may operate on an arbitrary number of collection partitions (even 1), socombop
may be invoked an arbitrary number of times (even 0).As an example, consider summing up the integer values of a list of chars. The initial value for the sum is 0. First,
seqop
transforms each input character to an Int and adds it to the sum (of the partition). Then,combop
just needs to sum up the intermediate results of the partitions:List('a', 'b', 'c').aggregate(0)({ (sum, ch) => sum + ch.toInt }, { (p1, p2) => p1 + p2 })
- 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 or0
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
-
abstract
def
count(p: (A) ⇒ Boolean): Int
Counts the number of elements in the collection or iterator which satisfy a predicate.
Counts the number of elements in the collection or iterator which satisfy a predicate.
- p
the predicate used to test elements.
- returns
the number of elements satisfying the predicate
p
.
-
abstract
def
exists(p: (A) ⇒ Boolean): Boolean
Tests whether a predicate holds for at least one element of this collection or iterator.
Tests whether a predicate holds for at least one element of this collection or iterator.
Note: may not terminate for infinite-sized collections.
- p
the predicate used to test elements.
- returns
true
if the given predicatep
is satisfied by at least one element of this collection or iterator, otherwisefalse
-
abstract
def
find(p: (A) ⇒ Boolean): Option[A]
Finds the first element of the collection or iterator satisfying a predicate, if any.
Finds the first element of the collection 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.
- p
the predicate used to test elements.
- returns
an option value containing the first element in the collection or iterator that satisfies
p
, orNone
if none exists.
-
abstract
def
fold[A1 >: A](z: A1)(op: (A1, A1) ⇒ A1): A1
Folds the elements of this collection or iterator using the specified associative binary operator.
Folds the elements of this collection or iterator using the specified associative binary operator.
The order in which operations are performed on elements is unspecified and may be nondeterministic.
Note: will not terminate for infinite-sized collections.
- 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 the fold operator
op
between all the elements andz
, orz
if this collection or iterator is empty.
-
abstract
def
foldLeft[B](z: B)(op: (B, A) ⇒ B): B
Applies a binary operator to a start value and all elements of this collection or iterator, going left to right.
Applies a binary operator to a start value and all elements of this collection 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 collection or iterator, 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 collection or iterator. Returnsz
if this collection or iterator is empty.
-
abstract
def
foldRight[B](z: B)(op: (A, B) ⇒ B): B
Applies a binary operator to all elements of this collection or iterator and a start value, going right to left.
Applies a binary operator to all elements of this collection 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 collection or iterator, 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 collection or iterator. Returnsz
if this collection or iterator is empty.
-
abstract
def
forall(p: (A) ⇒ Boolean): Boolean
Tests whether a predicate holds for all elements of this collection or iterator.
Tests whether a predicate holds for all elements of this collection or iterator.
Note: may not terminate for infinite-sized collections.
- p
the predicate used to test elements.
- returns
true
if this collection or iterator is empty or the given predicatep
holds for all elements of this collection or iterator, otherwisefalse
.
-
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
hasDefiniteSize: Boolean
Tests whether this collection or iterator is known to have a finite size.
Tests whether this collection or iterator 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 returnstrue
if all elements have been computed. It returnsfalse
if the stream is not yet evaluated to the end. Non-empty Iterators usually returnfalse
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
returnstrue
. However, checkinghasDefiniteSize
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.
-
abstract
def
isEmpty: Boolean
Tests whether the collection or iterator is empty.
Tests whether the collection or iterator 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 or iterator contains no elements,false
otherwise.
-
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.
-
abstract
def
mkString: String
Displays all elements of this collection or iterator in a string.
Displays all elements of this collection or iterator in a string.
- returns
a string representation of this collection or iterator. In the resulting string the string representations (w.r.t. the method
toString
) of all elements of this collection or iterator follow each other without any separator string.
-
abstract
def
mkString(sep: String): String
Displays all elements of this collection or iterator in a string using a separator string.
Displays all elements of this collection or iterator in a string using a separator string.
- sep
the separator string.
- returns
a string representation of this collection or iterator. In the resulting string the string representations (w.r.t. the method
toString
) of all elements of this collection or iterator are separated by the stringsep
.
List(1, 2, 3).mkString("|") = "1|2|3"
Example: -
abstract
def
mkString(start: String, sep: String, end: String): String
Displays all elements of this collection or iterator in a string using start, end, and separator strings.
Displays all elements of this collection 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 collection or iterator. 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 collection or iterator are separated by the stringsep
.
List(1, 2, 3).mkString("(", "; ", ")") = "(1; 2; 3)"
Example: -
abstract
def
nonEmpty: Boolean
Tests whether the collection or iterator is not empty.
Tests whether the collection or iterator is not empty.
- returns
true
if the collection or iterator contains at least one element,false
otherwise.
-
abstract
def
reduce[A1 >: A](op: (A1, A1) ⇒ A1): A1
Reduces the elements of this collection or iterator using the specified associative binary operator.
Reduces the elements of this collection 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 collection or iterator is nonempty.
- Exceptions thrown
UnsupportedOperationException
if this collection or iterator is empty.
-
abstract
def
reduceLeftOption[B >: A](op: (B, A) ⇒ B): Option[B]
Optionally applies a binary operator to all elements of this collection or iterator, going left to right.
Optionally applies a binary operator to all elements of this collection 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 collection or iterator is nonempty,None
otherwise.
-
abstract
def
reduceOption[A1 >: A](op: (A1, A1) ⇒ A1): Option[A1]
Reduces the elements of this collection or iterator, if any, using the specified associative binary operator.
Reduces the elements of this collection 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, andNone
otherwise.
-
abstract
def
reduceRight[B >: A](op: (A, B) ⇒ B): B
Applies a binary operator to all elements of this collection or iterator, going right to left.
Applies a binary operator to all elements of this collection 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 collection 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 collection or iterator.
- Exceptions thrown
UnsupportedOperationException
if this collection or iterator is empty.
-
abstract
def
reduceRightOption[B >: A](op: (A, B) ⇒ B): Option[B]
Optionally applies a binary operator to all elements of this collection or iterator, going right to left.
Optionally applies a binary operator to all elements of this collection 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 collection or iterator is nonempty,None
otherwise.
- abstract def seq: TraversableOnce[A]
-
abstract
def
size: Int
The size of this collection or iterator.
The size of this collection or iterator.
Note: will not terminate for infinite-sized collections.
- returns
the number of elements in this collection or iterator.
-
abstract
def
toBuffer[A1 >: A]: Buffer[A1]
Uses the contents of this collection or iterator to create a new mutable buffer.
Uses the contents of this collection or iterator to create a new mutable buffer.
Note: will not terminate for infinite-sized collections.
- returns
a buffer containing all elements of this collection or iterator.
-
abstract
def
toIndexedSeq: immutable.IndexedSeq[A]
Converts this collection or iterator to an indexed sequence.
Converts this collection or iterator to an indexed sequence.
Note: will not terminate for infinite-sized collections.
- returns
an indexed sequence containing all elements of this collection or iterator.
-
abstract
def
toIterable: GenIterable[A]
Converts this collection or iterator to an iterable collection.
Converts this collection or iterator to an iterable collection. Note that the choice of target
Iterable
is lazy in this default implementation as thisTraversableOnce
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 collection or iterator.
-
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.
-
abstract
def
toList: List[A]
Converts this collection or iterator to a list.
Converts this collection or iterator to a list.
Note: will not terminate for infinite-sized collections.
- returns
a list containing all elements of this collection or iterator.
-
abstract
def
toSeq: GenSeq[A]
Converts this collection or iterator to a sequence.
Converts this collection or iterator to a sequence. As with
toIterable
, it's lazy in this default implementation, as thisTraversableOnce
may be lazy and unevaluated.Note: will not terminate for infinite-sized collections.
- returns
a sequence containing all elements of this collection or iterator.
-
abstract
def
toSet[A1 >: A]: GenSet[A1]
Converts this collection or iterator to a set.
Converts this collection or iterator to a set.
Note: will not terminate for infinite-sized collections.
- returns
a set containing all elements of this collection or iterator.
-
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.
-
abstract
def
toTraversable: GenTraversable[A]
Converts this collection or iterator to an unspecified Traversable.
Converts this collection 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 collection or iterator.
-
abstract
def
toVector: Vector[A]
Converts this collection or iterator to a Vector.
Converts this collection or iterator to a Vector.
Note: will not terminate for infinite-sized collections.
- returns
a vector containing all elements of this collection or iterator.
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 GenTraversableOnce[A] to any2stringadd[GenTraversableOnce[A]] performed by method any2stringadd in scala.Predef.
- Definition Classes
- any2stringadd
-
def
->[B](y: B): (GenTraversableOnce[A], B)
- Implicit
- This member is added by an implicit conversion from GenTraversableOnce[A] to ArrowAssoc[GenTraversableOnce[A]] 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
-
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
.
-
abstract
def
copyToArray(xs: Array[A], start: Int, len: Int): Unit
[use case] Copies the elements of this collection or iterator to an array.
[use case]Copies the elements of this collection or iterator to an array. Fills the given array
xs
with at mostlen
elements of this collection or iterator, starting at positionstart
. Copying will stop once either the end of the current collection or iterator is reached, or the end of the target array is reached, orlen
elements have been copied.Note: will not terminate for infinite-sized collections.
- xs
the array to fill.
- start
the starting index.
- len
the maximal number of elements to copy.
-
abstract
def
copyToArray(xs: Array[A], start: Int): Unit
[use case] Copies the elements of this collection or iterator to an array.
[use case]Copies the elements of this collection or iterator to an array. Fills the given array
xs
with values of this collection or iterator, beginning at indexstart
. Copying will stop once either the end of the current collection or iterator is reached, or the end of the target array is reached.Note: will not terminate for infinite-sized collections.
- xs
the array to fill.
- start
the starting index.
-
abstract
def
copyToArray(xs: Array[A]): Unit
[use case] Copies the elements of this collection or iterator to an array.
[use case]Copies the elements of this collection or iterator to an array. Fills the given array
xs
with values of this collection or iterator. Copying will stop once either the end of the current collection or iterator is reached, or the end of the target array is reached.Note: will not terminate for infinite-sized collections.
- xs
the array to fill.
-
def
ensuring(cond: (GenTraversableOnce[A]) ⇒ Boolean, msg: ⇒ Any): GenTraversableOnce[A]
- Implicit
- This member is added by an implicit conversion from GenTraversableOnce[A] to Ensuring[GenTraversableOnce[A]] performed by method Ensuring in scala.Predef.
- Definition Classes
- Ensuring
-
def
ensuring(cond: (GenTraversableOnce[A]) ⇒ Boolean): GenTraversableOnce[A]
- Implicit
- This member is added by an implicit conversion from GenTraversableOnce[A] to Ensuring[GenTraversableOnce[A]] performed by method Ensuring in scala.Predef.
- Definition Classes
- Ensuring
-
def
ensuring(cond: Boolean, msg: ⇒ Any): GenTraversableOnce[A]
- Implicit
- This member is added by an implicit conversion from GenTraversableOnce[A] to Ensuring[GenTraversableOnce[A]] performed by method Ensuring in scala.Predef.
- Definition Classes
- Ensuring
-
def
ensuring(cond: Boolean): GenTraversableOnce[A]
- Implicit
- This member is added by an implicit conversion from GenTraversableOnce[A] to Ensuring[GenTraversableOnce[A]] 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
-
abstract
def
foreach(f: (A) ⇒ Unit): Unit
[use case] Applies a function
f
to all elements of this collection or iterator.[use case]Applies a function
f
to all elements of this collection or iterator.Note: this method underlies the implementation of most other bulk operations. It's important to implement this method in an efficient way.
- f
the function that is applied for its side-effect to every element. The result of function
f
is discarded.
Full Signatureabstract def foreach[U](f: (A) ⇒ U): Unit
-
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 GenTraversableOnce[A] to StringFormat[GenTraversableOnce[A]] 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
-
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
-
abstract
def
max: A
[use case] Finds the largest element.
[use case]Finds the largest element.
- returns
the largest element of this collection or iterator.
Full Signatureabstract def max[A1 >: A](implicit ord: Ordering[A1]): A
-
abstract
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 collection or iterator with the largest value measured by function f.
Full Signatureabstract def maxBy[B](f: (A) ⇒ B)(implicit cmp: Ordering[B]): A
-
abstract
def
min: A
[use case] Finds the smallest element.
[use case]Finds the smallest element.
- returns
the smallest element of this collection or iterator
Full Signatureabstract def min[A1 >: A](implicit ord: Ordering[A1]): A
-
abstract
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 collection or iterator with the smallest value measured by function f.
Full Signatureabstract def minBy[B](f: (A) ⇒ B)(implicit cmp: Ordering[B]): A
-
abstract
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 collection or iterator of numbers of type
Int
. Instead ofInt
, any other typeT
with an implicitNumeric[T]
implementation can be used as element type of the collection or iterator and as result type ofproduct
. Examples of such types are:Long
,Float
,Double
,BigInt
.
Full Signatureabstract def product[A1 >: A](implicit num: Numeric[A1]): A1
-
def
sizeHintIfCheap: Int
The size of this collection or iterator, if it can be cheaply computed
The size of this collection or iterator, if it can be cheaply computed
- returns
the number of elements in this collection or iterator, or -1 if the size cannot be determined cheaply
- Attributes
- protected[scala.collection]
-
abstract
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 collection or iterator of numbers of type
Int
. Instead ofInt
, any other typeT
with an implicitNumeric[T]
implementation can be used as element type of the collection or iterator and as result type ofsum
. Examples of such types are:Long
,Float
,Double
,BigInt
.
Full Signatureabstract def sum[A1 >: A](implicit num: Numeric[A1]): A1
-
abstract
def
to[Col[_]]: Col[A]
[use case] Converts this collection or iterator into another by copying all elements.
[use case]Converts this collection 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 collection or iterator.
Full Signatureabstract def to[Col[_]](implicit cbf: CanBuildFrom[Nothing, A, Col[A]]): Col[A]
-
abstract
def
toArray: Array[A]
[use case] Converts this collection or iterator to an array.
[use case]Converts this collection or iterator to an array.
Note: will not terminate for infinite-sized collections.
- returns
an array containing all elements of this collection or iterator. An
ClassTag
must be available for the element type of this collection or iterator.
-
abstract
def
toMap[T, U]: Map[T, U]
[use case] Converts this collection or iterator to a map.
[use case]Converts this collection 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 collection or iterator.
-
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
→[B](y: B): (GenTraversableOnce[A], B)
- Implicit
- This member is added by an implicit conversion from GenTraversableOnce[A] to ArrowAssoc[GenTraversableOnce[A]] performed by method ArrowAssoc in scala.Predef.
- Definition Classes
- ArrowAssoc
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.collection.parallel.immutable
- Immutable, parallel data-structures such asParVector
,ParRange
,ParHashMap
orParHashSet
scala.collection.parallel.mutable
- Mutable, parallel data-structures such asParArray
,ParHashMap
,ParTrieMap
orParHashSet
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.swing
- A convenient wrapper around Java's GUI framework called Swing (scala-swing.jar)scala.util.parsing
- Parser combinators (scala-parser-combinators.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
.