The class of the iterator returned by the iterator
method.
The type implementing this traversable
The type implementing this traversable
A class supporting filtered operations.
Selects an element by its index in the sequence.
Selects an element by its index in the sequence.
Example:
scala> val x = LinkedList(1, 2, 3, 4, 5) x: scala.collection.mutable.LinkedList[Int] = LinkedList(1, 2, 3, 4, 5) scala> x(3) res1: Int = 4
The index to select.
the element of this sequence at index idx
, where 0
indicates the first element.
if idx
does not satisfy 0 <= idx < length
.
Returns the runtime class representation of the object.
Returns the runtime class representation of the object.
a class object corresponding to the runtime type of the receiver.
The length of the sequence.
The length of the sequence.
Note: xs.length
and xs.size
yield the same result.
the number of elements in this sequence.
Creates a new builder for this collection type.
Creates a new builder for this collection type.
A version of this collection with all of the operations implemented sequentially (i.
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.
a sequential view of the collection.
Test two objects for inequality.
Test two objects for inequality.
true
if !(this == that), false otherwise.
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
.
a hash value consistent with ==
[use case] Returns a new sequence containing the elements from the left hand operand followed by the elements from the right hand operand.
Returns a new sequence containing the elements from the left hand operand followed by the elements from the right hand operand. The element type of the sequence is the most specific superclass encompassing the element types of the two operands.
Example:
scala> val a = LinkedList(1) a: scala.collection.mutable.LinkedList[Int] = LinkedList(1) scala> val b = LinkedList(2) b: scala.collection.mutable.LinkedList[Int] = LinkedList(2) scala> val c = a ++ b c: scala.collection.mutable.LinkedList[Int] = LinkedList(1, 2) scala> val d = LinkedList('a') d: scala.collection.mutable.LinkedList[Char] = LinkedList(a) scala> val e = c ++ d e: scala.collection.mutable.LinkedList[AnyVal] = LinkedList(1, 2, a)
the element type of the returned collection.
the traversable to append.
a new sequence which contains all elements of this sequence
followed by all elements of that
.
As with ++
, returns a new collection containing the elements from the
left operand followed by the elements from the right operand.
As with ++
, returns a new collection containing the elements from the
left operand followed by the elements from the right operand.
It differs from ++
in that the right operand determines the type of
the resulting collection rather than the left one.
Mnemonic: the COLon is on the side of the new COLlection type.
Example:
scala> val x = List(1) x: List[Int] = List(1) scala> val y = LinkedList(2) y: scala.collection.mutable.LinkedList[Int] = LinkedList(2) scala> val z = x ++: y z: scala.collection.mutable.LinkedList[Int] = LinkedList(1, 2)
This overload exists because: for the implementation of ++:
we should
reuse that of ++
because many collections override it with more
efficient versions.
Since TraversableOnce
has no ++
method, we have to implement that
directly, but Traversable
and down can use the overload.
the element type of the returned collection.
the class of the returned collection. Where possible, That
is
the same class as the current collection class Repr
, but this
depends on the element type B
being admissible for that class,
which means that an implicit instance of type CanBuildFrom[Repr, B, That]
is found.
the traversable to append.
an implicit value of class CanBuildFrom
which determines the
result class That
from the current representation type Repr
and the new element type B
.
a new collection of type That
which contains all elements
of this sequence followed by all elements of that
.
[use case] As with ++
, returns a new collection containing the elements from the left operand followed by the
elements from the right operand.
As with ++
, returns a new collection containing the elements from the left operand followed by the
elements from the right operand.
It differs from ++
in that the right operand determines the type of
the resulting collection rather than the left one.
Mnemonic: the COLon is on the side of the new COLlection type.
Example:
scala> val x = List(1) x: List[Int] = List(1) scala> val y = LinkedList(2) y: scala.collection.mutable.LinkedList[Int] = LinkedList(2) scala> val z = x ++: y z: scala.collection.mutable.LinkedList[Int] = LinkedList(1, 2)
the element type of the returned collection.
the traversable to append.
a new sequence which contains all elements of this sequence
followed by all elements of that
.
[use case] A copy of the sequence with an element prepended.
A copy of the sequence with an element prepended.
Note that :-ending operators are right associative (see example).
A mnemonic for +:
vs. :+
is: the COLon goes on the COLlection side.
Also, the original sequence is not modified, so you will want to capture the result.
Example:
scala> val x = LinkedList(1) x: scala.collection.mutable.LinkedList[Int] = LinkedList(1) scala> val y = 2 +: x y: scala.collection.mutable.LinkedList[Int] = LinkedList(2, 1) scala> println(x) LinkedList(1)
the prepended element
a new sequence consisting of elem
followed
by all elements of this sequence.
Applies a binary operator to a start value and all elements of this sequence, going left to right.
Applies a binary operator to a start value and all elements of this sequence, 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 = LinkedList(1,2,3,4) a: scala.collection.mutable.LinkedList[Int] = LinkedList(1, 2, 3, 4) scala> val b = (5 /: a)(_+_) b: Int = 15 scala> val c = (5 /: a)((x,y) => x + y) c: Int = 15
the result type of the binary operator.
the start value.
the binary operator.
the result of inserting op
between consecutive elements of this sequence,
going left to right with the start value z
on the left:
op(...op(op(z, x_1), x_2), ..., x_n)
where x_{1}, ..., x_{n}
are the elements of this sequence.
[use case] A copy of this sequence with an element appended.
A copy of this sequence with an element appended.
A mnemonic for +:
vs. :+
is: the COLon goes on the COLlection side.
Example:
scala> import scala.collection.mutable.LinkedList import scala.collection.mutable.LinkedList scala> val a = LinkedList(1) a: scala.collection.mutable.LinkedList[Int] = LinkedList(1) scala> val b = a :+ 2 b: scala.collection.mutable.LinkedList[Int] = LinkedList(1, 2) scala> println(a) LinkedList(1)
the appended element
a new sequence consisting of
all elements of this sequence followed by elem
.
Applies a binary operator to all elements of this sequence and a start value, going right to left.
Applies a binary operator to all elements of this sequence and a start value, going right to left.
Note: :\
is alternate syntax for foldRight
; xs :\ z
is the same as
xs foldRight z
.
Examples:
Note that the folding function used to compute b is equivalent to that used to compute c.
scala> val a = LinkedList(1,2,3,4) a: scala.collection.mutable.LinkedList[Int] = LinkedList(1, 2, 3, 4) scala> val b = (a :\ 5)(_+_) b: Int = 15 scala> val c = (a :\ 5)((x,y) => x + y) c: Int = 15
the result type of the binary operator.
the start value
the binary operator
the result of inserting op
between consecutive elements of this sequence,
going right to left with the start value z
on the right:
op(x_1, op(x_2, ... op(x_n, z)...))
where x_{1}, ..., x_{n}
are the elements of this sequence.
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)
.
true
if the receiver object is equivalent to the argument; false
otherwise.
Appends all elements of this sequence to a string builder.
Appends all elements of this sequence to a string builder.
The written text consists of the string representations (w.r.t. the method
toString
) of all elements of this sequence without any separator string.
Example:
scala> val a = LinkedList(1,2,3,4) a: scala.collection.mutable.LinkedList[Int] = LinkedList(1, 2, 3, 4) scala> val b = new StringBuilder() b: StringBuilder = scala> val h = a.addString(b) b: StringBuilder = 1234
the string builder to which elements are appended.
the string builder b
to which elements were appended.
Appends all elements of this sequence to a string builder using a separator string.
Appends all elements of this sequence 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 sequence, separated by the string sep
.
Example:
scala> val a = LinkedList(1,2,3,4) a: scala.collection.mutable.LinkedList[Int] = LinkedList(1, 2, 3, 4) scala> val b = new StringBuilder() b: StringBuilder = scala> a.addString(b, ", ") res0: StringBuilder = 1, 2, 3, 4
the string builder to which elements are appended.
the separator string.
the string builder b
to which elements were appended.
Appends all elements of this sequence to a string builder using start, end, and separator strings.
Appends all elements of this sequence 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 sequence are separated by the string sep
.
Example:
scala> val a = LinkedList(1,2,3,4) a: scala.collection.mutable.LinkedList[Int] = LinkedList(1, 2, 3, 4) scala> val b = new StringBuilder() b: StringBuilder = scala> a.addString(b, "LinkedList(", ", ", ")") res1: StringBuilder = LinkedList(1, 2, 3, 4)
the string builder to which elements are appended.
the starting string.
the separator string.
the ending string.
the string builder b
to which elements were appended.
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).
the type of accumulated results
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)
an operator used to accumulate results within a partition
an associative operator used to combine results from different partitions
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.
the receiver object.
if the receiver object is not an instance of the erasure of type T0
.
Method called from equality methods, so that user-defined subclasses can refuse to be equal to other collections of the same kind.
Method called from equality methods, so that user-defined subclasses can refuse to be equal to other collections of the same kind.
The object with which this sequence should be compared
true
, if this sequence can possibly equal that
, false
otherwise. The test
takes into consideration only the run-time types of objects but ignores their elements.
[use case] Builds a new collection by applying a partial function to all elements of this sequence on which the function is defined.
Builds a new collection by applying a partial function to all elements of this sequence on which the function is defined.
the element type of the returned collection.
the partial function which filters and maps the sequence.
a new sequence 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.
Finds the first element of the sequence for which the given partial function is defined, and applies the partial function to it.
Finds the first element of the sequence for which the given partial function is defined, and applies the partial function to it.
the partial function
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)
Iterates over combinations.
Iterates over combinations.
An Iterator which traverses the possible n-element combinations of this sequence.
"abbbc".combinations(2) = Iterator(ab, ac, bb, bc)
Tests whether this sequence contains a given value as an element.
Tests whether this sequence contains a given value as an element.
the element to test.
true
if this sequence has an element that is equal (as
determined by ==
) to elem
, false
otherwise.
Tests whether this sequence contains a given sequence as a slice.
Tests whether this sequence contains a given sequence as a slice.
the sequence to test
true
if this sequence contains a slice with the same elements
as that
, otherwise false
.
[use case] Copies elements of this sequence to an array.
Copies elements of this sequence to an array.
Fills the given array xs
with at most len
elements of
this sequence, starting at position start
.
Copying will stop once either the end of the current sequence is reached,
or the end of the array is reached, or len
elements have been copied.
the array to fill.
the starting index.
the maximal number of elements to copy.
[use case] Copies values of this sequence to an array.
Copies values of this sequence to an array.
Fills the given array xs
with values of this sequence.
Copying will stop once either the end of the current sequence is reached,
or the end of the array is reached.
the array to fill.
[use case] Copies values of this sequence to an array.
Copies values of this sequence to an array.
Fills the given array xs
with values of this sequence, beginning at index start
.
Copying will stop once either the end of the current sequence is reached,
or the end of the array is reached.
the array to fill.
the starting index.
Copies all elements of this sequence to a buffer.
Copies all elements of this sequence to a buffer.
The buffer to which elements are copied.
Tests whether every element of this sequence relates to the corresponding element of another sequence by satisfying a test predicate.
Tests whether every element of this sequence relates to the corresponding element of another sequence by satisfying a test predicate.
the type of the elements of that
the other sequence
the test predicate, which relates elements from both sequences
true
if both sequences have the same length and
p(x, y)
is true
for all corresponding elements x
of this sequence
and y
of that
, otherwise false
.
Counts the number of elements in the sequence which satisfy a predicate.
Counts the number of elements in the sequence which satisfy a predicate.
the predicate used to test elements.
the number of elements satisfying the predicate p
.
[use case] Computes the multiset difference between this sequence and another sequence.
Computes the multiset difference between this sequence and another sequence.
the sequence of elements to remove
a new sequence which contains all elements of this sequence
except some of occurrences of elements that also appear in that
.
If an element value x
appears
n times in that
, then the first n occurrences of x
will not form
part of the result, but any following occurrences will.
Builds a new sequence from this sequence without any duplicate elements.
Builds a new sequence from this sequence without any duplicate elements.
A new sequence which contains the first occurrence of every element of this sequence.
Selects all elements except first n ones.
Selects all elements except first n ones.
the number of elements to drop from this sequence.
a sequence consisting of all elements of this sequence except the first n
ones, or else the
empty sequence, if this sequence has less than n
elements.
Selects all elements except last n ones.
Selects all elements except last n ones.
The number of elements to take
a sequence consisting of all elements of this sequence except the last n
ones, or else the
empty sequence, if this sequence has less than n
elements.
Drops longest prefix of elements that satisfy a predicate.
Drops longest prefix of elements that satisfy a predicate.
the longest suffix of this sequence whose first element
does not satisfy the predicate p
.
Tests whether this sequence ends with the given sequence.
Tests whether this sequence ends with the given sequence.
the sequence to test
true
if this sequence has that
as a suffix, false
otherwise.
The equals method for arbitrary sequences.
The equals method for arbitrary sequences. Compares this sequence to some other object.
The object to compare the sequence to
true
if that
is a sequence that has the same elements as
this sequence in the same order, false
otherwise
Tests whether a predicate holds for some of the elements of this sequence.
Tests whether a predicate holds for some of the elements of this sequence.
the predicate used to test elements.
true
if the given predicate p
holds for some of the
elements of this sequence, otherwise false
.
Selects all elements of this sequence which satisfy a predicate.
Selects all elements of this sequence which satisfy a predicate.
the predicate used to test elements.
a new sequence consisting of all elements of this sequence that satisfy the given
predicate p
. The order of the elements is preserved.
Selects all elements of this sequence which do not satisfy a predicate.
Selects all elements of this sequence which do not satisfy a predicate.
the predicate used to test elements.
a new sequence consisting of all elements of this sequence that do not satisfy the given
predicate p
. The order of the elements is preserved.
Finds the first element of the sequence satisfying a predicate, if any.
Finds the first element of the sequence satisfying a predicate, if any.
the predicate used to test elements.
an option value containing the first element in the sequence
that satisfies p
, or None
if none exists.
[use case] Builds a new collection by applying a function to all elements of this sequence and using the elements of the resulting collections.
Builds a new collection by applying a function to all elements of this sequence 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 sequence. 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 a 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)
the element type of the returned collection.
the function to apply to each element.
a new sequence resulting from applying the given collection-valued function
f
to each element of this sequence and concatenating the results.
Folds the elements of this sequence using the specified associative binary operator.
Folds the elements of this sequence using the specified associative binary operator.
The order in which operations are performed on elements is unspecified and may be nondeterministic.
a type parameter for the binary operator, a supertype of A
.
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.)
a binary operator that must be associative
the result of applying fold operator op
between all the elements and z
Applies a binary operator to a start value and all elements of this sequence, going left to right.
Applies a binary operator to a start value and all elements of this sequence, going left to right.
the result type of the binary operator.
the start value.
the binary operator.
the result of inserting op
between consecutive elements of this sequence,
going left to right with the start value z
on the left:
op(...op(z, x_1), x_2, ..., x_n)
where x_{1}, ..., x_{n}
are the elements of this sequence.
Applies a binary operator to all elements of this sequence and a start value, going right to left.
Applies a binary operator to all elements of this sequence and a start value, going right to left.
the result type of the binary operator.
the start value.
the binary operator.
the result of inserting op
between consecutive elements of this sequence,
going right to left with the start value z
on the right:
op(x_1, op(x_2, ... op(x_n, z)...))
where x_{1}, ..., x_{n}
are the elements of this sequence.
Tests whether a predicate holds for all elements of this sequence.
Tests whether a predicate holds for all elements of this sequence.
the predicate used to test elements.
true
if the given predicate p
holds for all elements
of this sequence, otherwise false
.
[use case] Applies a function f
to all elements of this sequence.
Applies a function f
to all elements of this sequence.
Note: this method underlies the implementation of most other bulk operations. Subclasses should re-implement this method if a more efficient implementation exists.
the function that is applied for its side-effect to every element.
The result of function f
is discarded.
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).
Partitions this sequence into a map of sequences according to some discriminator function.
Partitions this sequence into a map of sequences according to some discriminator function.
Note: this method is not re-implemented by views. This means when applied to a view it will always force the view and return a new sequence.
the type of keys returned by the discriminator function.
the discriminator function.
A map from keys to sequences such that the following invariant holds:
(xs partition f)(k) = xs filter (x => f(x) == k)
That is, every key k
is bound to a sequence of those elements x
for which f(x)
equals k
.
Partitions elements in fixed size sequences.
Partitions elements in fixed size sequences.
the number of elements per group
An iterator producing sequences of size size
, except the
last will be truncated if the elements don't divide evenly.
scala.collection.Iterator, method grouped
Tests whether this sequence is known to have a finite size.
Tests whether this sequence is known to have a finite size.
All strict collections are known to have finite size. For a non-strict
collection such as Stream
, the predicate returns true
if all
elements have been computed. It returns false
if the stream is
not yet evaluated to the end.
Note: many collection methods will not work on collections of infinite sizes.
true
if this collection is known to have finite size,
false
otherwise.
Hashcodes for IndexedSeq produce a value from the hashcodes of all the elements of the sequence.
Hashcodes for IndexedSeq produce a value from the hashcodes of all the elements of the sequence.
the hash code value for this object.
Selects the first element of this sequence.
Selects the first element of this sequence.
the first element of this sequence.
if the sequence is empty.
Optionally selects the first element.
Optionally selects the first element.
the first element of this sequence if it is nonempty,
None
if it is empty.
[use case] Finds index of first occurrence of some value in this sequence after or at some start index.
Finds index of first occurrence of some value in this sequence after or at some start index.
the element value to search for.
the start index
the index >= from
of the first element of this sequence that is equal (as determined by ==
)
to elem
, or -1
, if none exists.
[use case] Finds index of first occurrence of some value in this sequence.
Finds index of first occurrence of some value in this sequence.
the element value to search for.
the index of the first element of this sequence that is equal (as determined by ==
)
to elem
, or -1
, if none exists.
Finds first index after or at a start index where this sequence contains a given sequence as a slice.
Finds first index after or at a start index where this sequence contains a given sequence as a slice.
the sequence to test
the start index
the first index >= from
such that the elements of this sequence starting at this index
match the elements of sequence that
, or -1
of no such subsequence exists.
Finds first index where this sequence contains a given sequence as a slice.
Finds first index where this sequence contains a given sequence as a slice.
the sequence to test
the first index such that the elements of this sequence starting at this index
match the elements of sequence that
, or -1
of no such subsequence exists.
Finds index of the first element satisfying some predicate after or at some start index.
Finds index of the first element satisfying some predicate after or at some start index.
the predicate used to test elements.
the start index
the index >= from
of the first element of this sequence that satisfies the predicate p
,
or -1
, if none exists.
Finds index of first element satisfying some predicate.
Finds index of first element satisfying some predicate.
the predicate used to test elements.
the index of the first element of this sequence that satisfies the predicate p
,
or -1
, if none exists.
Produces the range of all indices of this sequence.
Produces the range of all indices of this sequence.
a Range
value from 0
to one less than the length of this sequence.
Selects all elements except the last.
Selects all elements except the last.
a sequence consisting of all elements of this sequence except the last one.
if the sequence is empty.
Iterates over the inits of this sequence.
Iterates over the inits of this sequence. The first value will be this
sequence and the final one will be an empty sequence, with the intervening
values the results of successive applications of init
.
an iterator over all the inits of this sequence
List(1,2,3).inits = Iterator(List(1,2,3), List(1,2), List(1), Nil)
[use case] Computes the multiset intersection between this sequence and another sequence.
Computes the multiset intersection between this sequence and another sequence.
the sequence of elements to intersect with.
a new sequence which contains all elements of this sequence
which also appear in that
.
If an element value x
appears
n times in that
, then the first n occurrences of x
will be retained
in the result, but any following occurrences will be omitted.
Tests whether this sequence contains given index.
Tests whether this sequence contains given index.
The implementations of methods apply
and isDefinedAt
turn a Seq[A]
into
a PartialFunction[Int, A]
.
the index to test
true
if this sequence contains an element at position idx
, false
otherwise.
Tests whether this sequence is empty.
Tests whether this sequence is empty.
true
if the sequence contain no elements, false
otherwise.
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.
true
if the receiver object is an instance of erasure of type T0
; false
otherwise.
Tests whether this sequence can be repeatedly traversed.
Tests whether this sequence can be repeatedly traversed.
true
Creates a new iterator over all elements contained in this iterable object.
Creates a new iterator over all elements contained in this iterable object.
the new iterator
Selects the last element.
Selects the last element.
The last element of this sequence.
If the sequence is empty.
[use case] Finds index of last occurrence of some value in this sequence before or at a given end index.
Finds index of last occurrence of some value in this sequence before or at a given end index.
the element value to search for.
the end index.
the index <= end
of the last element of this sequence that is equal (as determined by ==
)
to elem
, or -1
, if none exists.
[use case] Finds index of last occurrence of some value in this sequence.
Finds index of last occurrence of some value in this sequence.
the element value to search for.
the index of the last element of this sequence that is equal (as determined by ==
)
to elem
, or -1
, if none exists.
Finds last index before or at a given end index where this sequence contains a given sequence as a slice.
Finds last index before or at a given end index where this sequence contains a given sequence as a slice.
the sequence to test
the end index
the last index <= end
such that the elements of this sequence starting at this index
match the elements of sequence that
, or -1
of no such subsequence exists.
Finds last index where this sequence contains a given sequence as a slice.
Finds last index where this sequence contains a given sequence as a slice.
the sequence to test
the last index such that the elements of this sequence starting a this index
match the elements of sequence that
, or -1
of no such subsequence exists.
Finds index of last element satisfying some predicate before or at given end index.
Finds index of last element satisfying some predicate before or at given end index.
the predicate used to test elements.
the index <= end
of the last element of this sequence that satisfies the predicate p
,
or -1
, if none exists.
Finds index of last element satisfying some predicate.
Finds index of last element satisfying some predicate.
the predicate used to test elements.
the index of the last element of this sequence that satisfies the predicate p
,
or -1
, if none exists.
Optionally selects the last element.
Optionally selects the last element.
the last element of this sequence$ if it is nonempty,
None
if it is empty.
Compares the length of this sequence to a test value.
Compares the length of this sequence to a test value.
the test value that gets compared with the length.
A value x
where
x < 0 if this.length < len x == 0 if this.length == len x > 0 if this.length > len
The method as implemented here does not call length
directly; its running time
is O(length min len)
instead of O(length)
. The method should be overwritten
if computing length
is cheap.
[use case] Builds a new collection by applying a function to all elements of this sequence.
Builds a new collection by applying a function to all elements of this sequence.
the element type of the returned collection.
the function to apply to each element.
a new sequence resulting from applying the given function
f
to each element of this sequence and collecting the results.
[use case] Finds the largest element.
Finds the largest element.
the largest element of this sequence.
[use case] Finds the smallest element.
Finds the smallest element.
the smallest element of this sequence
Displays all elements of this sequence in a string.
Displays all elements of this sequence in a string.
a string representation of this sequence. In the resulting string
the string representations (w.r.t. the method toString
)
of all elements of this sequence follow each other without any
separator string.
Displays all elements of this sequence in a string using a separator string.
Displays all elements of this sequence in a string using a separator string.
the separator string.
a string representation of this sequence. In the resulting string
the string representations (w.r.t. the method toString
)
of all elements of this sequence are separated by the string sep
.
List(1, 2, 3).mkString("|") = "1|2|3"
Displays all elements of this sequence in a string using start, end, and separator strings.
Displays all elements of this sequence in a string using start, end, and separator strings.
the starting string.
the separator string.
the ending string.
a string representation of this sequence. 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 sequence are separated by
the string sep
.
List(1, 2, 3).mkString("(", "; ", ")") = "(1; 2; 3)"
Tests whether the sequence is not empty.
Tests whether the sequence is not empty.
true
if the sequence contains at least one element, false
otherwise.
[use case] A copy of this sequence with an element value appended until a given target length is reached.
A copy of this sequence with an element value appended until a given target length is reached.
the target length
the padding value
a new sequence consisting of
all elements of this sequence followed by the minimal number of occurrences of elem
so
that the resulting sequence has a length of at least len
.
Returns a parallel implementation of this collection.
Returns a parallel implementation of this collection.
For most collection types, this method creates a new parallel collection by copying
all the elements. For these collection, par
takes linear time. Mutable collections
in this category do not produce a mutable parallel collection that has the same
underlying dataset, so changes in one collection will not be reflected in the other one.
Specific collections (e.g. ParArray
or mutable.ParHashMap
) override this default
behaviour by creating a parallel collection which shares the same underlying dataset.
For these collections, par
takes constant or sublinear time.
All parallel collections return a reference to themselves.
a parallel implementation of this collection
The default par
implementation uses the combiner provided by this method
to create a new parallel collection.
The default par
implementation uses the combiner provided by this method
to create a new parallel collection.
a combiner for the parallel collection of type ParRepr
Partitions this sequence in two sequences according to a predicate.
Partitions this sequence in two sequences according to a predicate.
the predicate on which to partition.
a pair of sequences: the first sequence consists of all elements that
satisfy the predicate p
and the second sequence consists of all elements
that don't. The relative order of the elements in the resulting sequences
is the same as in the original sequence.
[use case] Produces a new sequence where a slice of elements in this sequence is replaced by another sequence.
Produces a new sequence where a slice of elements in this sequence is replaced by another sequence.
the index of the first replaced element
the number of elements to drop in the original sequence
a new sequence consisting of all elements of this sequence
except that replaced
elements starting from from
are replaced
by patch
.
Iterates over distinct permutations.
Iterates over distinct permutations.
An Iterator which traverses the distinct permutations of this sequence.
"abb".permutations = Iterator(abb, bab, bba)
Returns the length of the longest prefix whose elements all satisfy some predicate.
Returns the length of the longest prefix whose elements all satisfy some predicate.
the predicate used to test elements.
the length of the longest prefix of this sequence
such that every element of the segment satisfies the predicate p
.
[use case] Multiplies up the elements of this collection.
Multiplies up the elements of this collection.
the product of all elements in this sequence 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 sequence and as result type of product
.
Examples of such types are: Long
, Float
, Double
, BigInt
.
Reduces the elements of this sequence using the specified associative binary operator.
Reduces the elements of this sequence using the specified associative binary operator.
The order in which operations are performed on elements is unspecified and may be nondeterministic.
A type parameter for the binary operator, a supertype of A
.
A binary operator that must be associative.
The result of applying reduce operator op
between all the elements if the sequence is nonempty.
if this sequence is empty.
Applies a binary operator to all elements of this sequence, going left to right.
Applies a binary operator to all elements of this sequence, going left to right.
the result type of the binary operator.
the binary operator.
the result of inserting op
between consecutive elements of this sequence,
going left to right:
op( op( ... op(x_1, x_2) ..., x_{n-1}), x_n)
where x_{1}, ..., x_{n}
are the elements of this sequence.
if this sequence is empty.
Optionally applies a binary operator to all elements of this sequence, going left to right.
Optionally applies a binary operator to all elements of this sequence, going left to right.
the result type of the binary operator.
the binary operator.
an option value containing the result of reduceLeft(op)
is this sequence is nonempty,
None
otherwise.
Reduces the elements of this sequence, if any, using the specified associative binary operator.
Reduces the elements of this sequence, if any, using the specified associative binary operator.
The order in which operations are performed on elements is unspecified and may be nondeterministic.
A type parameter for the binary operator, a supertype of A
.
A binary operator that must be associative.
An option value containing result of applying reduce operator op
between all
the elements if the collection is nonempty, and None
otherwise.
Applies a binary operator to all elements of this sequence, going right to left.
Applies a binary operator to all elements of this sequence, going right to left.
the result type of the binary operator.
the binary operator.
the result of inserting op
between consecutive elements of this sequence,
going right to left:
op(x_1, op(x_2, ..., op(x_{n-1}, x_n)...))
where x_{1}, ..., x_{n}
are the elements of this sequence.
if this sequence is empty.
Optionally applies a binary operator to all elements of this sequence, going right to left.
Optionally applies a binary operator to all elements of this sequence, going right to left.
the result type of the binary operator.
the binary operator.
an option value containing the result of reduceRight(op)
is this sequence is nonempty,
None
otherwise.
The collection of type sequence underlying this TraversableLike
object.
The collection of type sequence underlying this TraversableLike
object.
By default this is implemented as the TraversableLike
object itself,
but this can be overridden.
Returns new sequence wih elements in reversed order.
Returns new sequence wih elements in reversed order.
A new sequence with all elements of this sequence in reversed order.
An iterator yielding elements in reversed order.
An iterator yielding elements in reversed order.
Note: xs.reverseIterator
is the same as xs.reverse.iterator
but might be more efficient.
an iterator yielding the elements of this sequence in reversed order
[use case] Builds a new collection by applying a function to all elements of this sequence and collecting the results in reversed order.
Builds a new collection by applying a function to all elements of this sequence and collecting the results in reversed order.
Note: xs.reverseMap(f)
is the same as xs.reverse.map(f)
but might be more efficient.
the element type of the returned collection.
the function to apply to each element.
a new sequence resulting from applying the given function
f
to each element of this sequence and collecting the results in reversed order.
[use case] Checks if the other iterable collection contains the same elements in the same order as this sequence.
Checks if the other iterable collection contains the same elements in the same order as this sequence.
the collection to compare with.
true
, if both collections contain the same elements in the same order, false
otherwise.
Computes a prefix scan of the elements of the collection.
Computes a prefix scan of the elements of the collection.
Note: The neutral element z
may be applied more than once.
element type of the resulting collection
type of the resulting collection
neutral element for the operator op
the associative operator for the scan
combiner factory which provides a combiner
a new sequence containing the prefix scan of the elements in this sequence
Produces a collection containing cumulative results of applying the operator going left to right.
Produces a collection containing cumulative results of applying the operator going left to right.
the type of the elements in the resulting collection
the actual type of the resulting collection
the initial value
the binary operator applied to the intermediate result and the element
an implicit value of class CanBuildFrom
which determines the
result class That
from the current representation type Repr
and the new element type B
.
collection with intermediate results
Produces a collection containing cumulative results of applying the operator going right to left.
Produces a collection containing cumulative results of applying the operator going right to left. The head of the collection is the last cumulative result.
Example:
List(1, 2, 3, 4).scanRight(0)(_ + _) == List(10, 9, 7, 4, 0)
the type of the elements in the resulting collection
the actual type of the resulting collection
the initial value
the binary operator applied to the intermediate result and the element
an implicit value of class CanBuildFrom
which determines the
result class That
from the current representation type Repr
and the new element type B
.
collection with intermediate results
(Changed in version 2.9.0) The behavior of scanRight
has changed. The previous behavior can be reproduced with scanRight.reverse.
Computes length of longest segment whose elements all satisfy some predicate.
Computes length of longest segment whose elements all satisfy some predicate.
the predicate used to test elements.
the index where the search starts.
the length of the longest segment of this sequence starting from index from
such that every element of the segment satisfies the predicate p
.
The size of this sequence, equivalent to length
.
The size of this sequence, equivalent to length
.
the number of elements in this sequence.
Selects an interval of elements.
Selects an interval of elements. The returned collection is made up
of all elements x
which satisfy the invariant:
from <= indexOf(x) < until
a sequence containing the elements greater than or equal to
index from
extending up to (but not including) index until
of this sequence.
Groups elements in fixed size blocks by passing a "sliding window" over them (as opposed to partitioning them, as is done in grouped.
Groups elements in fixed size blocks by passing a "sliding window" over them (as opposed to partitioning them, as is done in grouped.)
the number of elements per group
the distance between the first elements of successive groups (defaults to 1)
An iterator producing sequences of size size
, except the
last and the only element will be truncated if there are
fewer elements than size.
scala.collection.Iterator, method sliding
Groups elements in fixed size blocks by passing a "sliding window" over them (as opposed to partitioning them, as is done in grouped.
Groups elements in fixed size blocks by passing a "sliding window" over them (as opposed to partitioning them, as is done in grouped.)
the number of elements per group
An iterator producing sequences of size size
, except the
last and the only element will be truncated if there are
fewer elements than size.
scala.collection.Iterator, method sliding
Sorts this IndexedSeq according to the Ordering which results from transforming an implicitly given Ordering with a transformation function.
Sorts this IndexedSeq according to the Ordering which results from transforming an implicitly given Ordering with a transformation function.
the target type of the transformation f
, and the type where
the ordering ord
is defined.
the transformation function mapping elements
to some other domain B
.
the ordering assumed on domain B
.
a sequence consisting of the elements of this sequence
sorted according to the ordering where x < y
if
ord.lt(f(x), f(y))
.
val words = "The quick brown fox jumped over the lazy dog".split(' ') // this works because scala.Ordering will implicitly provide an Ordering[Tuple2[Int, Char]] words.sortBy(x => (x.length, x.head)) res0: Array[String] = Array(The, dog, fox, the, lazy, over, brown, quick, jumped)
Sorts this sequence according to a comparison function.
Sorts this sequence according to a comparison function.
The sort is stable. That is, elements that are equal (as determined by
lt
) appear in the same order in the sorted sequence as in the original.
the comparison function which tests whether its first argument precedes its second argument in the desired ordering.
a sequence consisting of the elements of this sequence
sorted according to the comparison function lt
.
List("Steve", "Tom", "John", "Bob").sortWith(_.compareTo(_) < 0) = List("Bob", "John", "Steve", "Tom")
Sorts this sequence according to an Ordering.
Sorts this sequence according to an Ordering.
The sort is stable. That is, elements that are equal (as determined by
lt
) appear in the same order in the sorted sequence as in the original.
the ordering to be used to compare elements.
a sequence consisting of the elements of this sequence
sorted according to the ordering ord
.
Splits this sequence into a prefix/suffix pair according to a predicate.
Splits this sequence into a prefix/suffix pair according to a predicate.
Note: c span p
is equivalent to (but possibly more efficient than)
(c takeWhile p, c dropWhile p)
, provided the evaluation of the
predicate p
does not cause any side-effects.
a pair consisting of the longest prefix of this sequence whose
elements all satisfy p
, and the rest of this sequence.
Splits this sequence into two at a given position.
Splits this sequence into two at a given position.
Note: c splitAt n
is equivalent to (but possibly more efficient than)
(c take n, c drop n)
.
the position at which to split.
a pair of sequences consisting of the first n
elements of this sequence, and the other elements.
Tests whether this sequence contains the given sequence at a given index.
Tests whether this sequence contains the given sequence at a given index.
Note: If the both the receiver object this
and the argument
that
are infinite sequences this method may not terminate.
the sequence to test
the index where the sequence is searched.
true
if the sequence that
is contained in this sequence at
index offset
, otherwise false
.
Tests whether this sequence starts with the given sequence.
Tests whether this sequence starts with the given sequence.
the sequence to test
true
if this collection has that
as a prefix, false
otherwise.
Defines the prefix of this object's toString
representation.
Defines the prefix of this object's toString
representation.
a string representation which starts the result of toString
applied to this sequence. By default the string prefix is the
simple name of the collection class sequence.
[use case] Sums up the elements of this collection.
Sums up the elements of this collection.
the sum of all elements in this sequence 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 sequence and as result type of sum
.
Examples of such types are: Long
, Float
, Double
, BigInt
.
Selects all elements except the first.
Selects all elements except the first.
a sequence consisting of all elements of this sequence except the first one.
if the sequence is empty.
Iterates over the tails of this sequence.
Iterates over the tails of this sequence. The first value will be this
sequence and the final one will be an empty sequence, with the intervening
values the results of successive applications of tail
.
an iterator over all the tails of this sequence
List(1,2,3).tails = Iterator(List(1,2,3), List(2,3), List(3), Nil)
Selects first n elements.
Selects first n elements.
the number of elements to take from this sequence.
a sequence consisting only of the first n
elements of this sequence,
or else the whole sequence, if it has less than n
elements.
Selects last n elements.
Selects last n elements.
the number of elements to take
a sequence consisting only of the last n
elements of this sequence, or else the
whole sequence, if it has less than n
elements.
Takes longest prefix of elements that satisfy a predicate.
Takes longest prefix of elements that satisfy a predicate.
the longest prefix of this sequence whose elements all satisfy
the predicate p
.
The underlying collection seen as an instance of IndexedSeq
.
The underlying collection seen as an instance of IndexedSeq
.
By default this is implemented as the current collection object itself,
but this can be overridden.
[use case] Converts this sequence into another by copying all elements.
Converts this sequence into another by copying all elements.
The collection type to build.
a new collection containing all elements of this sequence.
[use case] Converts this sequence to an array.
Converts this sequence to an array.
an array containing all elements of this sequence.
An ClassTag
must be available for the element type of this sequence.
Converts this sequence to a mutable buffer.
Converts this sequence to a mutable buffer.
a buffer containing all elements of this sequence.
A conversion from collections of type Repr
to IndexedSeq
objects.
A conversion from collections of type Repr
to IndexedSeq
objects.
By default this is implemented as just a cast, but this can be overridden.
Converts this sequence to an indexed sequence.
Converts this sequence to an indexed sequence.
an indexed sequence containing all elements of this sequence.
Converts this sequence to an iterable collection.
Converts this sequence 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).
an Iterable
containing all elements of this sequence.
Returns an Iterator over the elements in this sequence.
Returns an Iterator over the elements in this sequence. Will return the same Iterator if this instance is already an Iterator.
an Iterator containing all elements of this sequence.
Converts this sequence to a list.
Converts this sequence to a list.
a list containing all elements of this sequence.
[use case] Converts this sequence to a map.
Converts this sequence 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.
a map of type immutable.Map[T, U]
containing all key/value pairs of type (T, U)
of this sequence.
Converts this sequence to a sequence.
Converts this sequence to a sequence.
Overridden for efficiency.
a sequence containing all elements of this sequence.
Converts this sequence to a set.
Converts this sequence to a set.
a set containing all elements of this sequence.
Converts this sequence to a stream.
Converts this sequence to a stream.
a stream containing all elements of this sequence.
Converts this sequence to a string.
Converts this sequence to a string.
a string representation of this collection. By default this
string consists of the stringPrefix
of this sequence, followed
by all elements separated by commas and enclosed in parentheses.
Converts this sequence to an unspecified Traversable.
Converts this sequence to an unspecified Traversable. Will return the same collection if this instance is already Traversable.
a Traversable containing all elements of this sequence.
Converts this sequence to a Vector.
Converts this sequence to a Vector.
a vector containing all elements of this sequence.
[use case] Produces a new sequence which contains all elements of this sequence and also all elements of a given sequence.
Produces a new sequence which contains all elements of this sequence and also all elements of
a given sequence. xs union ys
is equivalent to xs ++ ys
.
Another way to express this
is that xs union ys
computes the order-presevring multi-set union of xs
and ys
.
union
is hence a counter-part of diff
and intersect
which also work on multi-sets.
the sequence to add.
a new sequence which contains all elements of this sequence
followed by all elements of that
.
[use case] A copy of this sequence with one single replaced element.
A copy of this sequence with one single replaced element.
the position of the replacement
the replacing element
a copy of this sequence with the element at position index
replaced by elem
.
Creates a non-strict view of a slice of this sequence.
Creates a non-strict view of a slice of this sequence.
Note: the difference between view
and slice
is that view
produces
a view of the current sequence, whereas slice
produces a new sequence.
Note: view(from, to)
is equivalent to view.slice(from, to)
the index of the first element of the view
the index of the element following the view
a non-strict view of a slice of this sequence, starting at index from
and extending up to (but not including) index until
.
Creates a non-strict view of this sequence.
Creates a non-strict view of this sequence.
a non-strict view of this sequence.
Creates a non-strict filter of this sequence.
Creates a non-strict filter of this sequence.
Note: the difference between c filter p
and c withFilter p
is that
the former creates a new collection, whereas the latter only
restricts the domain of subsequent map
, flatMap
, foreach
,
and withFilter
operations.
the predicate used to test elements.
an object of class WithFilter
, which supports
map
, flatMap
, foreach
, and withFilter
operations.
All these operations apply to those elements of this sequence
which satisfy the predicate p
.
[use case] Returns a sequence formed from this sequence and another iterable collection by combining corresponding elements in pairs.
Returns a sequence formed from this sequence and another iterable collection by combining corresponding elements in pairs. If one of the two collections is longer than the other, its remaining elements are ignored.
the type of the second half of the returned pairs
The iterable providing the second half of each result pair
a new sequence containing pairs consisting of
corresponding elements of this sequence and that
. The length
of the returned collection is the minimum of the lengths of this sequence and that
.
[use case] Returns a sequence formed from this sequence and another iterable collection by combining corresponding elements in pairs.
Returns a sequence formed from this sequence and another iterable collection by combining corresponding elements in pairs. If one of the two collections is shorter than the other, placeholder elements are used to extend the shorter collection to the length of the longer.
the type of the second half of the returned pairs
The iterable providing the second half of each result pair
the element to be used to fill up the result if this sequence is shorter than that
.
the element to be used to fill up the result if that
is shorter than this sequence.
a new sequence containing pairs consisting of
corresponding elements of this sequence and that
. The length
of the returned collection is the maximum of the lengths of this sequence and that
.
If this sequence is shorter than that
, thisElem
values are used to pad the result.
If that
is shorter than this sequence, thatElem
values are used to pad the result.
[use case] Zips this sequence with its indices.
Zips this sequence with its indices.
A new sequence containing pairs consisting of all elements of this
sequence paired with their index. Indices start at 0
.
List("a", "b", "c").zipWithIndex = List(("a", 0), ("b", 1), ("c", 2))
(indexedSeqLike: MonadOps[A]).filter(p)
(indexedSeqLike: MonadOps[A]).flatMap(f)
(indexedSeqLike: MonadOps[A]).map(f)
(indexedSeqLike: StringAdd).self
(indexedSeqLike: StringFormat).self
(indexedSeqLike: MonadOps[A]).withFilter(p)
A syntactic sugar for out of order folding.
A syntactic sugar for out of order folding. See fold
.
Example:
scala> val a = LinkedList(1,2,3,4) a: scala.collection.mutable.LinkedList[Int] = LinkedList(1, 2, 3, 4) scala> val b = (a /:\ 5)(_+_) b: Int = 15
(Since version 2.10.0) use fold instead
(indexedSeqLike: ArrowAssoc[IndexedSeqLike[A, Repr]]).x
(Since version 2.10.0) Use leftOfArrow
instead
(indexedSeqLike: Ensuring[IndexedSeqLike[A, Repr]]).x
(Since version 2.10.0) Use resultOfEnsuring
instead
A template trait for indexed sequences of type
IndexedSeq[A]
.Indexed sequences support constant-time or near constant-time element access and length computation. They are defined in terms of abstract methods
apply
for indexing andlength
.Indexed sequences do not add any new methods to
Seq
, but promise efficient implementations of random access patterns.This trait just implements
iterator
in terms ofapply
andlength
. However, seeIndexedSeqOptimized
for an implementation trait that overrides operations to make them run faster under the assumption of fast random access withapply
.