Test two objects for inequality.
true
if !(this == that), false otherwise.
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 ==
Alias for concat
Alias for prependedAll
Alias for prepended
.
Note that :-ending operators are right associative (see example). A mnemonic for +:
vs. :+
is: the COLon goes on the COLlection side.
Alias for appended
Note that :-ending operators are right associative (see example). A mnemonic for +:
vs. :+
is: the COLon goes on the COLlection side.
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 collection to a string builder. The written text consists of the string representations (w.r.t. the method toString
) of all elements of this collection without any separator string.
Example:
scala> val a = List(1,2,3,4) a: List[Int] = List(1, 2, 3, 4) scala> val b = new StringBuilder() b: StringBuilder = scala> val h = a.addString(b) h: StringBuilder = 1234
the string builder to which elements are appended.
the string builder b
to which elements were appended.
Appends all elements of this collection to a string builder using a separator string. The written text consists of the string representations (w.r.t. the method toString
) of all elements of this collection, separated by the string sep
.
Example:
scala> val a = List(1,2,3,4) a: List[Int] = List(1, 2, 3, 4) scala> val b = new StringBuilder() b: StringBuilder = scala> a.addString(b, ", ") res0: StringBuilder = 1, 2, 3, 4
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 collection to a string builder using start, end, and separator strings. The written text begins with the string start
and ends with the string end
. Inside, the string representations (w.r.t. the method toString
) of all elements of this collection are separated by the string sep
.
Example:
scala> val a = List(1,2,3,4) a: List[Int] = List(1, 2, 3, 4) scala> val b = new StringBuilder() b: StringBuilder = scala> a.addString(b , "List(" , ", " , ")") res5: StringBuilder = List(1, 2, 3, 4)
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.
Composes this partial function with another partial function that gets applied to results of this partial function.
Note that calling isDefinedAt on the resulting partial function may apply the first partial function and execute its side effect. It is highly recommended to call applyOrElse instead of isDefinedAt / apply for efficiency.
the result type of the transformation function.
the transformation function
a partial function with the domain of this partial function narrowed by other partial function, which maps arguments x
to k(this(x))
.
Composes this partial function with a transformation function that gets applied to results of this partial function.
If the runtime type of the function is a PartialFunction
then the other andThen
method is used (note its cautions).
the result type of the transformation function.
the transformation function
a partial function with the domain of this partial function, possibly narrowed by the specified function, which maps arguments x
to k(this(x))
.
A copy of this sequence with an element appended.
Note: will not terminate for infinite-sized collections.
Example:
scala> val a = List(1) a: List[Int] = List(1) scala> val b = a :+ 2 b: List[Int] = List(1, 2) scala> println(a) List(1)
the element type of the returned sequence.
the appended element
a new sequence consisting of all elements of this sequence followed by value
.
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.
the element type of the returned collection.
the iterable to append.
a new collection of type CC[B]
which contains all elements of this sequence followed by all elements of suffix
.
Get the element at the specified index. This operation is provided for convenience in Seq
. It should not be assumed to be efficient unless you have an IndexedSeq
.
Applies this partial function to the given argument when it is contained in the function domain. Applies fallback function where this partial function is not defined.
Note that expression pf.applyOrElse(x, default)
is equivalent to
if(pf isDefinedAt x) pf(x) else default(x)
except that applyOrElse
method can be implemented more efficiently. For all partial function literals the compiler generates an applyOrElse
implementation which avoids double evaluation of pattern matchers and guards. This makes applyOrElse
the basis for the efficient implementation for many operations and scenarios, such as:
orElse
/andThen
chains does not lead to excessive apply
/isDefinedAt
evaluation
lift
and unlift
do not evaluate source functions twice on each invocation
runWith
allows efficient imperative-style combining of partial functions with conditionally applied actions For non-literal partial function classes with nontrivial isDefinedAt
method it is recommended to override applyOrElse
with custom implementation that avoids double isDefinedAt
evaluation. This may result in better performance and more predictable behavior w.r.t. side effects.
the function argument
the fallback function
the result of this function or fallback function application.
2.10
a hint to the runtime when scanning values apply is perferred for scan with a max index less than this value iterator is preferred for scans above this range
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.
ClassCastException
if the receiver object is not an instance of the erasure of type T0
.
Create a new range with the start
and end
values of this range and a new step
.
a new range with a different step
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 immutable sequence should be compared
true
, if this immutable sequence can possibly equal that
, false
otherwise. The test takes into consideration only the run-time types of objects but ignores their elements.
Defines the prefix of this object's toString
representation.
It is recommended to return the name of the concrete collection type, but not implementation subclasses. For example, for ListMap
this method should return "ListMap"
, not "Map"
(the supertype) or "Node"
(an implementation subclass).
The default implementation returns "Iterable". It is overridden for the basic collection kinds "Seq", "IndexedSeq", "LinearSeq", "Buffer", "Set", "Map", "SortedSet", "SortedMap" and "View".
a string representation which starts the result of toString
applied to this range. By default the string prefix is the simple name of the collection class range.
Create a copy of the receiver object.
The default implementation of the clone
method is platform dependent.
a copy of the receiver object.
This collection as a C
.
Builds a new iterable collection by applying a partial function to all elements of this iterable collection on which the function is defined.
the element type of the returned iterable collection.
the partial function which filters and maps the iterable collection.
a new iterable collection resulting from applying the given partial function pf
to each element on which it is defined and collecting the results. The order of the elements is preserved.
Reuse: After calling this method, one should discard the iterator it was called on, and use only the iterator that was returned. Using the old iterator is undefined, subject to change, and may result in changes to the new iterator as well.
Finds the first element of the collection for which the given partial function is defined, and applies the partial function to it.
Note: may not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered.
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. A _combination_ of length n
is a subsequence of the original sequence, with the elements taken in order. Thus, "xy"
and "yy"
are both length-2 combinations of "xyy"
, but "yx"
is not. If there is more than one way to generate the same subsequence, only one will be returned.
For example, "xyyy"
has three different ways to generate "xy"
depending on whether the first, second, or third "y"
is selected. However, since all are identical, only one will be chosen. Which of the three will be taken is an implementation detail that is not defined.
Note: Even when applied to a view or a lazy collection it will always force the elements.
An Iterator which traverses the possible n-element combinations of this sequence.
"abbbc".combinations(2) = Iterator(ab, ac, bb, bc)
Composes another partial function k
with this partial function so that this partial function gets applied to results of k
.
Note that calling isDefinedAt on the resulting partial function may apply the first partial function and execute its side effect. It is highly recommended to call applyOrElse instead of isDefinedAt / apply for efficiency.
the parameter type of the transformation function.
the transformation function
a partial function with the domain of other partial function narrowed by this partial function, which maps arguments x
to this(k(x))
.
Composes two instances of Function1 in a new Function1, with this function applied last.
the type to which function g
can be applied
a function A => T1
a new function f
such that f(x) == apply(g(x))
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.
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 suffix
.
Tests whether this range contains a given value as an element.
the element to test.
true
if this range has an element that is equal (as determined by ==
) to elem
, false
otherwise.
Tests whether this sequence contains a given sequence as a slice.
Note: may not terminate for infinite-sized collections.
the sequence to test
true
if this sequence contains a slice with the same elements as that
, otherwise false
.
Copy elements to an array, returning the number of elements written.
Fills the given array xs
starting at index start
with at most len
elements of this collection.
Copying will stop once either all the elements of this collection have been copied, or the end of the array is reached, or len
elements have been copied.
the type of the elements of the array.
the array to fill.
the starting index of xs.
the maximal number of elements to copy.
the number of elements written to the array
Reuse: After calling this method, one should discard the iterator it was called on. Using it is undefined and subject to change. Note: will not terminate for infinite-sized collections.
Copy elements to an array, returning the number of elements written.
Fills the given array xs
starting at index start
with values of this collection.
Copying will stop once either all the elements of this collection have been copied, or the end of the array is reached.
the type of the elements of the array.
the array to fill.
the starting index of xs.
the number of elements written to the array Note: will not terminate for infinite-sized collections.
Copy elements to an array, returning the number of elements written.
Fills the given array xs
starting at index start
with values of this collection.
Copying will stop once either all the elements of this collection have been copied, or the end of the array is reached.
the type of the elements of the array.
the array to fill.
the number of elements written to the array Note: will not terminate for infinite-sized collections.
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
.
Tests whether every element of this collection's iterator relates to the corresponding element of another collection by satisfying a test predicate.
the type of the elements of that
the other collection
the test predicate, which relates elements from both collections
true
if both collections have the same length and p(x, y)
is true
for all corresponding elements x
of this iterator and y
of that
, otherwise false
Counts the number of elements in the collection which satisfy a predicate.
the predicate used to test elements.
the number of elements satisfying the predicate p
.
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.
Selects all the elements of this range ignoring the duplicates.
a new range consisting of all the elements of this range without duplicates.
Selects all the elements of this immutable sequence ignoring the duplicates as determined by ==
after applying the transforming function f
.
the type of the elements after being transformed by f
The transforming function whose result is used to determine the uniqueness of each element
a new immutable sequence consisting of all the elements of this immutable sequence without duplicates.
Creates a new range containing all the elements of this range except the first n
elements.
the number of elements to drop.
a new range consisting of all the elements of this range except n
first elements.
Creates a new range consisting of the initial length - n
elements of the range.
Note: this method does not use builders to construct a new range, and its complexity is O(1).
the number of elements to drop from this range.
a range consisting of all elements of this range except the last n
ones, or else the empty range, if this range has less than n
elements. If n
is negative, don't drop any elements.
Drops longest prefix of elements that satisfy a predicate.
The predicate used to test elements.
the longest suffix of this range whose first element does not satisfy the predicate p
.
Reuse: After calling this method, one should discard the iterator it was called on, and use only the iterator that was returned. Using the old iterator is undefined, subject to change, and may result in changes to the new iterator as well.
Returns an extractor object with a unapplySeq
method, which extracts each element of a sequence data.
val firstChar: String => Option[Char] = _.headOption Seq("foo", "bar", "baz") match { case firstChar.unlift.elementWise(c0, c1, c2) => println(s"$c0, $c1, $c2") // Output: f, b, b }
The empty iterable of the same type as this iterable
an empty iterable of type C
.
Tests whether this sequence ends with the given sequence.
Note: will not terminate for infinite-sized collections.
the sequence to test
true
if this sequence has that
as a suffix, false
otherwise.
Tests whether the argument (that
) is a reference to the receiver object (this
).
The eq
method implements an equivalence relation on non-null instances of AnyRef
, and has three additional properties:
x
and y
of type AnyRef
, multiple invocations of x.eq(y)
consistently returns true
or consistently returns false
.For any non-null instance x
of type AnyRef
, x.eq(null)
and null.eq(x)
returns false
.
null.eq(null)
returns true
. When overriding the equals
or hashCode
methods, it is important to ensure that their behavior is consistent with reference equality. Therefore, if two objects are references to each other (o1 eq o2
), they should be equal to each other (o1 == o2
) and they should hash to the same value (o1.hashCode == o2.hashCode
).
true
if the argument is a reference to the receiver object; false
otherwise.
The universal equality method defined in AnyRef
.
Tests whether a predicate holds for at least one element of this collection.
Note: may not terminate for infinite-sized collections.
the predicate used to test elements.
true
if the given predicate p
is satisfied by at least one element of this collection, otherwise false
Selects all elements of this iterable collection which satisfy a predicate.
a new iterator consisting of all elements of this iterable collection that satisfy the given predicate p
. The order of the elements is preserved.
Selects all elements of this iterable collection which do not satisfy a predicate.
the predicate used to test elements.
a new iterable collection consisting of all elements of this iterable collection that do not satisfy the given predicate pred
. Their order may not be preserved.
Called by the garbage collector on the receiver object when there are no more references to the object.
The details of when and if the finalize
method is invoked, as well as the interaction between finalize
and non-local returns and exceptions, are all platform dependent.
Finds the first element of the collection satisfying a predicate, if any.
Note: may not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered.
the predicate used to test elements.
an option value containing the first element in the collection that satisfies p
, or None
if none exists.
Finds the last element of the sequence satisfying a predicate, if any.
Note: will not terminate for infinite-sized collections.
the predicate used to test elements.
an option value containing the last element in the sequence that satisfies p
, or None
if none exists.
Builds a new iterable collection by applying a function to all elements of this iterable collection and using the elements of the resulting collections.
For example:
def getWords(lines: Seq[String]): Seq[String] = lines flatMap (line => line split "\\W+")
The type of the resulting collection is guided by the static type of iterable collection. This might cause unexpected results sometimes. For example:
// lettersOf will return a Seq[Char] of likely repeated letters, instead of a Set def lettersOf(words: Seq[String]) = words flatMap (word => word.toSet) // lettersOf will return a Set[Char], not a Seq def lettersOf(words: Seq[String]) = words.toSet flatMap ((word: String) => word.toSeq) // xs will be an Iterable[Int] val xs = Map("a" -> List(11,111), "b" -> List(22,222)).flatMap(_._2) // ys will be a Map[Int, Int] val ys = Map("a" -> List(1 -> 11,1 -> 111), "b" -> List(2 -> 22,2 -> 222)).flatMap(_._2)
the element type of the returned collection.
the function to apply to each element.
a new iterable collection resulting from applying the given collection-valued function f
to each element of this iterable collection and concatenating the results.
Reuse: After calling this method, one should discard the iterator it was called on, and use only the iterator that was returned. Using the old iterator is undefined, subject to change, and may result in changes to the new iterator as well.
Converts this iterable collection of traversable collections into a iterable collection formed by the elements of these traversable collections.
The resulting collection's type will be guided by the type of iterable collection. For example:
val xs = List( Set(1, 2, 3), Set(1, 2, 3) ).flatten // xs == List(1, 2, 3, 1, 2, 3) val ys = Set( List(1, 2, 3), List(3, 2, 1) ).flatten // ys == Set(1, 2, 3)
the type of the elements of each traversable collection.
a new iterable collection resulting from concatenating all element iterable collections.
Reuse: After calling this method, one should discard the iterator it was called on, and use only the iterator that was returned. Using the old iterator is undefined, subject to change, and may result in changes to the new iterator as well.
Folds the elements of this collection using the specified associative binary operator. The default implementation in IterableOnce
is equivalent to foldLeft
but may be overridden for more efficient traversal orders.
The order in which operations are performed on elements is unspecified and may be nondeterministic.
Note: will not terminate for infinite-sized collections.
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 the fold operator op
between all the elements and z
, or z
if this collection is empty.
Applies a binary operator to a start value and all elements of this collection, going left to right.
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.
the result type of the binary operator.
the start value.
the binary operator.
the result of inserting op
between consecutive elements of this collection, going left to right with the start value z
on the left:
op(...op(z, x_1), x_2, ..., x_n)
where x_{1}, ..., x_{n}
are the elements of this collection. Returns z
if this collection is empty.
Applies a binary operator to all elements of this collection and a start value, going right to left.
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.
the result type of the binary operator.
the start value.
the binary operator.
the result of inserting op
between consecutive elements of this collection, 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 collection. Returns z
if this collection is empty.
Tests whether a predicate holds for all elements of this collection.
Note: may not terminate for infinite-sized collections.
the predicate used to test elements.
true
if this collection is empty or the given predicate p
holds for all elements of this collection, otherwise false
.
Apply f
to each element for its side effects Note: [U] parameter needed to help scalac's type inference.
Returns string formatted according to given format
string. Format strings are as for String.format
(@see java.lang.String.format).
Defines how to turn a given Iterable[A]
into a collection of type C
.
This process can be done in a strict way or a non-strict way (ie. without evaluating the elements of the resulting collections). In other words, this methods defines the evaluation model of the collection.
When implementing a custom collection type and refining C
to the new type, this method needs to be overridden (the compiler will issue an error otherwise). In the common case where C =:= CC[A]
, this can be done by mixing in the IterableFactoryDefaults trait, which implements the method using iterableFactory.
As witnessed by the @uncheckedVariance
annotation, using this method might be unsound. However, as long as it is called with an Iterable[A]
obtained from this
collection (as it is the case in the implementations of operations where we use a View[A]
), it is safe.
Returns the runtime class representation of the object.
a class object corresponding to the runtime type of the receiver.
Partitions this iterable collection into a map of iterable collections according to some discriminator function.
Note: Even when applied to a view or a lazy collection it will always force the elements.
the type of keys returned by the discriminator function.
the discriminator function.
A map from keys to iterable collections such that the following invariant holds:
(xs groupBy f)(k) = xs filter (x => f(x) == k)
That is, every key k
is bound to a iterable collection of those elements x
for which f(x)
equals k
.
Partitions this iterable collection into a map of iterable collections according to a discriminator function key
. Each element in a group is transformed into a value of type B
using the value
function.
It is equivalent to groupBy(key).mapValues(_.map(f))
, but more efficient.
case class User(name: String, age: Int) def namesByAge(users: Seq[User]): Map[Int, Seq[String]] = users.groupMap(_.age)(_.name)
Note: Even when applied to a view or a lazy collection it will always force the elements.
the type of keys returned by the discriminator function
the type of values returned by the transformation function
the discriminator function
the element transformation function
Partitions this iterable collection into a map according to a discriminator function key
. All the values that have the same discriminator are then transformed by the value
function and then reduced into a single value with the reduce
function.
It is equivalent to groupBy(key).mapValues(_.map(f).reduce(reduce))
, but more efficient.
def occurrences[A](as: Seq[A]): Map[A, Int] = as.groupMapReduce(identity)(_ => 1)(_ + _)
Note: Even when applied to a view or a lazy collection it will always force the elements.
Partitions elements in fixed size ranges.
the number of elements per group
An iterator producing ranges of size size
, except the last will be less than size size
if the elements don't divide evenly.
scala.collection.Iterator, method grouped
The hashCode method for reference types. See hashCode in scala.Any.
the hash code value for this object.
Selects the first element of this range.
the first element of this range.
NoSuchElementException
if the range is empty.
Optionally selects the first element.
Note: might return different results for different runs, unless the underlying collection type is ordered.
the first element of this iterable collection if it is nonempty, None
if it is empty.
Finds index of first occurrence of some value in this range after or at some start index.
the type of the element elem
.
the element value to search for.
the start index
the index >= from
of the first element of this range that is equal (as determined by ==
) to elem
, or -1
, if none exists.
Finds index of first occurrence of some value in this sequence.
the type of the element elem
.
the element value to search for.
the index >= 0
of the first element of this sequence that is equal (as determined by ==
) to elem
, or -1
, if none exists.
Finds first index where this sequence contains a given sequence as a slice.
Note: may not terminate for infinite-sized collections.
the sequence to test
the first index >= 0
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 after or at a start index where this sequence contains a given sequence as a slice.
Note: may not terminate for infinite-sized collections.
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 index of the first element satisfying some predicate.
Note: may not terminate for infinite-sized collections.
the predicate used to test elements.
the index >= 0
of the first element of this sequence that satisfies the predicate p
, or -1
, if none exists.
Finds index of the first element satisfying some predicate after or at some start index.
Note: may not terminate for infinite-sized collections.
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.
Produces the range of all indices of this sequence.
Note: Even when applied to a view or a lazy collection it will always force the elements.
a Range
value from 0
to one less than the length of this sequence.
Creates a new range containing all the elements of this range except the last one.
Note: this method does not use builders to construct a new range, and its complexity is O(1).
a new range consisting of all the elements of this range except the last one.
Iterates over the inits of this range. The first value will be this range and the final one will be an empty range, with the intervening values the results of successive applications of init
.
Note: Even when applied to a view or a lazy collection it will always force the elements.
an iterator over all the inits of this range
List(1,2,3).inits = Iterator(List(1,2,3), List(1,2), List(1), Nil)
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.
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 the range is empty.
Note: Implementations in subclasses that are not repeatedly traversable must take care not to consume any elements when isEmpty
is called.
true
if the range contains no elements, false
otherwise.
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 iterable collection can be repeatedly traversed. Always true for Iterables and false for Iterators unless overridden.
true
if it is repeatedly traversable, false
otherwise.
The companion object of this immutable sequence, providing various factory methods.
When implementing a custom collection type and refining CC
to the new type, this method needs to be overridden to return a factory for the new type (the compiler will issue an error otherwise).
Iterator can be used only once
The number of elements in this sequence, if it can be cheaply computed, -1 otherwise. Cheaply usually means: Not requiring a collection traversal.
The last element of this range. This method will return the correct value even if there are too many elements to iterate over.
The last element of this range.
Finds index of last occurrence of some value in this range before or at a given end index.
the type of the element elem
.
the element value to search for.
the end index.
the index <= end
of the last element of this range that is equal (as determined by ==
) to elem
, or -1
, if none exists.
Finds last index where this sequence contains a given sequence as a slice.
Note: will not terminate for infinite-sized collections.
the sequence to test
the last 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 last index before or at a given end index where this sequence contains a given sequence as a slice.
Note: will not terminate for infinite-sized collections.
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 index of last element satisfying some predicate.
Note: will not terminate for infinite-sized collections.
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.
Finds index of last element satisfying some predicate before or at given end index.
Note: will not terminate for infinite-sized collections.
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.
Optionally selects the last element.
Note: might return different results for different runs, unless the underlying collection type is ordered.
the last element of this iterable collection$ if it is nonempty, None
if it is empty.
Analogous to zip
except that the elements in each collection are not consumed until a strict operation is invoked on the returned LazyZip2
decorator.
Calls to lazyZip
can be chained to support higher arities (up to 4) without incurring the expense of constructing and deconstructing intermediary tuples.
val xs = List(1, 2, 3) val res = (xs lazyZip xs lazyZip xs lazyZip xs).map((a, b, c, d) => a + b + c + d) // res == List(4, 8, 12)
the type of the second element in each eventual pair
the iterable providing the second element of each eventual pair
a decorator LazyZip2
that allows strict operations to be performed on the lazily evaluated pairs or chained calls to lazyZip
. Implicit conversion to Iterable[(A, B)]
is also supported.
The length (number of elements) of the range. size
is an alias for length
in Seq
collections.
Compares the length of this sequence to the size of another Iterable
.
the Iterable
whose size is compared with this sequence's length.
A value x
where
x < 0 if this.length < that.size x == 0 if this.length == that.size x > 0 if this.length > that.size
The method as implemented here does not call length
or size
directly; its running time is O(this.length min that.size)
instead of O(this.length + that.size)
. The method should be overridden if computing size
is cheap and knownSize
returns -1
.
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 overridden if computing length
is cheap and knownSize
returns -1
.
Returns a value class containing operations for comparing the length of this sequence to a test value.
These operations are implemented in terms of lengthCompare(Int)
, and allow the following more readable usages:
this.lengthIs < len // this.lengthCompare(len) < 0 this.lengthIs <= len // this.lengthCompare(len) <= 0 this.lengthIs == len // this.lengthCompare(len) == 0 this.lengthIs != len // this.lengthCompare(len) != 0 this.lengthIs >= len // this.lengthCompare(len) >= 0 this.lengthIs > len // this.lengthCompare(len) > 0
Turns this partial function into a plain function returning an Option
result.
a function that takes an argument x
to Some(this(x))
if this
is defined for x
, and to None
otherwise.
Function.unlift
Builds a new range by applying a function to all elements of this range.
the element type of the returned range.
the function to apply to each element.
a new range resulting from applying the given function f
to each element of this range and collecting the results.
Reuse: After calling this method, one should discard the iterator it was called on, and use only the iterator that was returned. Using the old iterator is undefined, subject to change, and may result in changes to the new iterator as well.
Finds the largest element.
An ordering to be used for comparing elements.
the largest element of this range with respect to the ordering ord
.
UnsupportedOperationException
if this range is empty.
Finds the first element which yields the largest value measured by function f.
The result type of the function f.
The measuring function.
An ordering to be used for comparing elements.
the first element of this collection with the largest value measured by function f with respect to the ordering cmp
.
UnsupportedOperationException
if this collection is empty.
Finds the first element which yields the largest value measured by function f.
The result type of the function f.
The measuring function.
An ordering to be used for comparing elements.
an option value containing the first element of this collection with the largest value measured by function f with respect to the ordering cmp
.
Finds the largest element.
The type over which the ordering is defined.
An ordering to be used for comparing elements.
an option value containing the largest element of this collection with respect to the ordering ord
.
Finds the smallest element.
An ordering to be used for comparing elements.
the smallest element of this range with respect to the ordering ord
.
UnsupportedOperationException
if this range is empty.
Finds the first element which yields the smallest value measured by function f.
The result type of the function f.
The measuring function.
An ordering to be used for comparing elements.
the first element of this collection with the smallest value measured by function f with respect to the ordering cmp
.
UnsupportedOperationException
if this collection is empty.
Finds the first element which yields the smallest value measured by function f.
The result type of the function f.
The measuring function.
An ordering to be used for comparing elements.
an option value containing the first element of this collection with the smallest value measured by function f with respect to the ordering cmp
.
Finds the smallest element.
The type over which the ordering is defined.
An ordering to be used for comparing elements.
an option value containing the smallest element of this collection with respect to the ordering ord
.
Displays all elements of this collection in a string.
Delegates to addString, which can be overridden.
a string representation of this collection. In the resulting string the string representations (w.r.t. the method toString
) of all elements of this collection follow each other without any separator string.
Displays all elements of this collection in a string using a separator string.
Delegates to addString, which can be overridden.
the separator string.
a string representation of this collection. In the resulting string the string representations (w.r.t. the method toString
) of all elements of this collection are separated by the string sep
.
List(1, 2, 3).mkString("|") = "1|2|3"
Displays all elements of this collection in a string using start, end, and separator strings.
Delegates to addString, which can be overridden.
the starting string.
the separator string.
the ending string.
a string representation of this collection. The resulting string begins with the string start
and ends with the string end
. Inside, the string representations (w.r.t. the method toString
) of all elements of this collection are separated by the string sep
.
List(1, 2, 3).mkString("(", "; ", ")") = "(1; 2; 3)"
Equivalent to !(this eq that)
.
true
if the argument is not a reference to the receiver object; false
otherwise.
a strict builder for the same collection type. Note that in the case of lazy collections (e.g. View or immutable.LazyList), it is possible to implement this method but the resulting Builder
will break laziness. As a consequence, operations should preferably be implemented with fromSpecific
instead of this method.
When implementing a custom collection type and refining C
to the new type, this method needs to be overridden (the compiler will issue an error otherwise). In the common case where C =:= CC[A]
, this can be done by mixing in the IterableFactoryDefaults trait, which implements the method using iterableFactory.
As witnessed by the @uncheckedVariance
annotation, using this method might be unsound. However, as long as the returned builder is only fed with A
values taken from this
instance, it is safe.
Tests whether the collection is not empty.
true
if the collection contains at least one element, false
otherwise.
Wakes up a single thread that is waiting on the receiver object's monitor.
not specified by SLS as a member of AnyRef
Wakes up all threads that are waiting on the receiver object's monitor.
not specified by SLS as a member of AnyRef
Composes this partial function with a fallback partial function which gets applied where this partial function is not defined.
the argument type of the fallback function
the result type of the fallback function
the fallback function
a partial function which has as domain the union of the domains of this partial function and that
. The resulting partial function takes x
to this(x)
where this
is defined, and to that(x)
where it is not.
A copy of this sequence with an element value appended until a given target length is reached.
the element type of the returned sequence.
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 collection has a length of at least len
.
A pair of, first, all elements that satisfy predicate p
and, second, all elements that do not. Interesting because it splits a collection in two.
The default implementation provided here needs to traverse the collection twice. Strict collections have an overridden version of partition
in StrictOptimizedIterableOps
, which requires only a single traversal.
Applies a function f
to each element of the iterable collection and returns a pair of iterable collections: the first one made of those values returned by f
that were wrapped in scala.util.Left, and the second one made of those wrapped in scala.util.Right.
Example:
val xs = Iterable(1, "one", 2, "two", 3, "three") partitionMap { case i: Int => Left(i) case s: String => Right(s) } // xs == (Iterable(1, 2, 3), // Iterable(one, two, three))
the element type of the first resulting collection
the element type of the second resulting collection
the 'split function' mapping the elements of this iterable collection to an scala.util.Either
a pair of iterable collections: the first one made of those values returned by f
that were wrapped in scala.util.Left, and the second one made of those wrapped in scala.util.Right.
Produces a new immutable sequence where a slice of elements in this immutable sequence is replaced by another sequence.
Patching at negative indices is the same as patching starting at 0. Patching at indices at or larger than the length of the original immutable sequence appends the patch to the end. If more values are replaced than actually exist, the excess is ignored.
the element type of the returned immutable sequence.
the index of the first replaced element
the replacement sequence
the number of elements to drop in the original immutable sequence
a new immutable sequence consisting of all elements of this immutable sequence except that replaced
elements starting from from
are replaced by all the elements of other
.
Iterates over distinct permutations.
Note: Even when applied to a view or a lazy collection it will always force the elements.
An Iterator which traverses the distinct permutations of this sequence.
"abb".permutations = Iterator(abb, bab, bba)
A copy of the sequence with an element prepended.
Also, the original sequence is not modified, so you will want to capture the result.
Example:
scala> val x = List(1) x: List[Int] = List(1) scala> val y = 2 +: x y: List[Int] = List(2, 1) scala> println(x) List(1)
the element type of the returned sequence.
the prepended element
a new sequence consisting of value
followed by all elements of this sequence.
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.
the element type of the returned collection.
the iterable to prepend.
a new sequence which contains all elements of prefix
followed by all the elements of this sequence.
Multiplies up the elements of this collection.
the result type of the *
operator.
an implicit parameter defining a set of numeric operations which includes the *
operator to be used in forming the product.
the product of all elements of this collection with respect to the *
operator in num
.
Reduces the elements of this collection using the specified associative binary operator.
The order in which operations are performed on elements is unspecified and may be nondeterministic.
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 collection is nonempty.
UnsupportedOperationException
if this collection is empty.
Applies a binary operator to all elements of this collection, going left to right.
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.
the result type of the binary operator.
the binary operator.
the result of inserting op
between consecutive elements of this collection, 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 collection.
UnsupportedOperationException
if this collection is empty.
Optionally applies a binary operator to all elements of this collection, going left to right.
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.
the result type of the binary operator.
the binary operator.
an option value containing the result of reduceLeft(op)
if this collection is nonempty, None
otherwise.
Reduces the elements of this collection, if any, using the specified associative binary operator.
The order in which operations are performed on elements is unspecified and may be nondeterministic.
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 collection, going right to left.
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.
the result type of the binary operator.
the binary operator.
the result of inserting op
between consecutive elements of this collection, 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 collection.
UnsupportedOperationException
if this collection is empty.
Optionally applies a binary operator to all elements of this collection, going right to left.
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.
the result type of the binary operator.
the binary operator.
an option value containing the result of reduceRight(op)
if this collection is nonempty, None
otherwise.
Returns the reverse of this range.
A new range with all elements of this range in reversed order.
An iterator yielding elements in reversed order.
Note: will not terminate for infinite-sized collections.
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
Composes this partial function with an action function which gets applied to results of this partial function. The action function is invoked only for its side effects; its result is ignored.
Note that expression pf.runWith(action)(x)
is equivalent to
if(pf isDefinedAt x) { action(pf(x)); true } else false
except that runWith
is implemented via applyOrElse
and thus potentially more efficient. Using runWith
avoids double evaluation of pattern matchers and guards for partial function literals.
the action function
a function which maps arguments x
to isDefinedAt(x)
. The resulting function runs action(this(x))
where this
is defined.
2.10
applyOrElse
.
Are the elements of this collection the same (and in the same order) as those of that
?
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
neutral element for the operator op
the associative operator for the scan
a new iterable collection containing the prefix scan of the elements in this iterable collection
Produces a iterable collection containing cumulative results of applying the operator going left to right, including the initial value.
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered.
the type of the elements in the resulting collection
the initial value
the binary operator applied to the intermediate result and the element
collection with intermediate results
Reuse: After calling this method, one should discard the iterator it was called on, and use only the iterator that was returned. Using the old iterator is undefined, subject to change, and may result in changes to the new iterator as well.
Produces a collection containing cumulative results of applying the operator going right to left. The head of the collection is the last cumulative result.
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered.
Note: Even when applied to a view or a lazy collection it will always force the elements.
Example:
List(1, 2, 3, 4).scanRight(0)(_ + _) == List(10, 9, 7, 4, 0)
the type of the elements in the resulting collection
the initial value
the binary operator applied to the intermediate result and the element
collection with intermediate results
Search within an interval in this sorted sequence for a specific element. If this sequence is an IndexedSeq
, a binary search is used. Otherwise, a linear search is used.
The sequence should be sorted with the same Ordering
before calling; otherwise, the results are undefined.
the element to find.
the index where the search starts.
the index following where the search ends.
the ordering to be used to compare elements.
a Found
value containing the index corresponding to the element in the sequence, or the InsertionPoint
where the element would be inserted if the element is not in the sequence.
if to <= from
, the search space is empty, and an InsertionPoint
at from
is returned
scala.collection.SeqOps, method sorted
Search this sorted sequence for a specific element. If the sequence is an IndexedSeq
, a binary search is used. Otherwise, a linear search is used.
The sequence should be sorted with the same Ordering
before calling; otherwise, the results are undefined.
the element to find.
the ordering to be used to compare elements.
a Found
value containing the index corresponding to the element in the sequence, or the InsertionPoint
where the element would be inserted if the element is not in the sequence.
scala.collection.SeqOps, method sorted
Computes length of longest segment whose elements all satisfy some predicate.
Note: may not terminate for infinite-sized collections.
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
.
Computes length of longest segment whose elements all satisfy some predicate.
Note: may not terminate for infinite-sized collections.
the predicate used to test elements.
the length of the longest segment of this sequence such that every element of the segment satisfies the predicate p
.
The size of this sequence.
Note: will not terminate for infinite-sized collections.
the number of elements in this sequence.
Compares the size of this sequence to the size of another Iterable
.
the Iterable
whose size is compared with this sequence's size.
A value x
where
x < 0 if this.size < that.size x == 0 if this.size == that.size x > 0 if this.size > that.size
The method as implemented here does not call size
directly; its running time is O(this.size min that.size)
instead of O(this.size + that.size)
. The method should be overridden if computing size
is cheap and knownSize
returns -1
.
Compares the size of this sequence to a test value.
the test value that gets compared with the size.
A value x
where
x < 0 if this.size < otherSize x == 0 if this.size == otherSize x > 0 if this.size > otherSize
The method as implemented here does not call size
directly; its running time is O(size min otherSize)
instead of O(size)
. The method should be overridden if computing size
is cheap and knownSize
returns -1
.
Returns a value class containing operations for comparing the size of this iterable collection to a test value.
These operations are implemented in terms of sizeCompare(Int)
, and allow the following more readable usages:
this.sizeIs < size // this.sizeCompare(size) < 0 this.sizeIs <= size // this.sizeCompare(size) <= 0 this.sizeIs == size // this.sizeCompare(size) == 0 this.sizeIs != size // this.sizeCompare(size) != 0 this.sizeIs >= size // this.sizeCompare(size) >= 0 this.sizeIs > size // this.sizeCompare(size) > 0
Creates a new range containing the elements starting at from
up to but not including until
.
Note: this method does not use builders to construct a new range, and its complexity is O(1).
the element at which to start
the element at which to end (not included in the range)
a new range consisting of a contiguous interval of values in the old range
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
An iterator producing iterable collections of size size
, except the last element (which may be the only element) will be truncated if there are fewer than size
elements remaining to be grouped.
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
.) The "sliding window" step is set to one.
the number of elements per group
An iterator producing iterable collections of size size
, except the last element (which may be the only element) will be truncated if there are fewer than size
elements remaining to be grouped.
scala.collection.Iterator, method sliding
Sorts this sequence according to the Ordering which results from transforming an implicitly given Ordering with a transformation function.
Note: will not terminate for infinite-sized collections.
Note: Even when applied to a view or a lazy collection it will always force the elements.
The sort is stable. That is, elements that are equal (as determined by ord.compare
) appear in the same order in the sorted sequence as in the original.
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.
Note: will not terminate for infinite-sized collections.
Note: Even when applied to a view or a lazy collection it will always force the elements.
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 range according to an Ordering.
The sort is stable. That is, elements that are equal (as determined by ord.compare
) appear in the same order in the sorted sequence as in the original.
the ordering to be used to compare elements.
a range consisting of the elements of this range sorted according to the ordering ord
.
scala.math.Ordering Note: Even when applied to a view or a lazy collection it will always force the elements.
Splits this range 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.
the test predicate
a pair consisting of the longest prefix of this range whose elements all satisfy p
, and the rest of this range.
Reuse: After calling this method, one should discard the iterator it was called on, and use only the iterators that were returned. Using the old iterator is undefined, subject to change, and may result in changes to the new iterators as well.
Splits this range into a prefix/suffix pair at a given position.
Note: c splitAt n
is equivalent to (but possibly more efficient than) (c take n, c drop n)
.
the position at which to split.
a pair of ranges consisting of the first n
elements of this range, and the other elements.
Reuse: After calling this method, one should discard the iterator it was called on, and use only the iterators that were returned. Using the old iterator is undefined, subject to change, and may result in changes to the new iterators as well.
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
.
Returns a Stepper for the elements of this collection.
The Stepper enables creating a Java stream to operate on the collection, see scala.jdk.StreamConverters. For collections holding primitive values, the Stepper can be used as an iterator which doesn't box the elements.
The implicit StepperShape parameter defines the resulting Stepper type according to the element type of this collection.
Int
, Short
, Byte
or Char
, an IntStepper is returnedFor collections of Double
or Float
, a DoubleStepper is returnedFor collections of Long
a LongStepper is returnedFor any other element type, an AnyStepper is returnedNote that this method is overridden in subclasses and the return type is refined to S with EfficientSplit
, for example IndexedSeqOps.stepper. For Steppers marked with scala.collection.Stepper.EfficientSplit, the converters in scala.jdk.StreamConverters allow creating parallel streams, whereas bare Steppers can be converted only to sequential streams.
Type of elements of the resulting collection (e.g. String
)
Type of the resulting collection (e.g. List[String]
)
Builder to use to build the resulting collection
Element transformation partial function
The resulting collection
Type of elements of the resulting collections (e.g. Int
)
Type of the resulting collection (e.g. List[Int]
)
Elements to concatenate to this collection
Builder to use to build the resulting collection
The resulting collection
Type of elements of the resulting collection (e.g. String
)
Type of the resulting collection (e.g. List[String]
)
Builder to use to build the resulting collection
Element transformation function
The resulting collection
Type of elements of the resulting collection (e.g. Int
)
Type of the resulting collection (e.g. List[Int]
)
Builder to use to build the resulting collection
Evidence that A
can be seen as an IterableOnce[B]
The resulting collection
Type of elements of the resulting collection (e.g. String
)
Type of the resulting collection (e.g. List[String]
)
Builder to use to build the resulting collection
Element transformation function
The resulting collection
Type of elements of the second collection (e.g. String
)
Type of the resulting collection (e.g. List[(Int, String)]
)
Collection to zip with this collection
Builder to use to build the resulting collection
The resulting collection
Sums up the elements of this collection.
the result type of the +
operator.
an implicit parameter defining a set of numeric operations which includes the +
operator to be used in forming the sum.
the sum of all elements of this range with respect to the +
operator in num
.
Creates a new range containing all the elements of this range except the first one.
Note: this method does not use builders to construct a new range, and its complexity is O(1).
a new range consisting of all the elements of this range except the first one.
Iterates over the tails of this range. The first value will be this range and the final one will be an empty range, with the intervening values the results of successive applications of tail
.
an iterator over all the tails of this range
List(1,2,3).tails = Iterator(List(1,2,3), List(2,3), List(3), Nil)
Creates a new range containing the first n
elements of this range.
the number of elements to take.
a new range consisting of n
first elements.
Creates a new range consisting of the last n
elements of the range.
Note: this method does not use builders to construct a new range, and its complexity is O(1).
the number of elements to take from this range.
a range consisting only of the last n
elements of this range, or else the whole range, if it has less than n
elements. If n
is negative, returns an empty range.
Takes longest prefix of elements that satisfy a predicate.
The predicate used to test elements.
the longest prefix of this range whose elements all satisfy the predicate p
.
Applies a side-effecting function to each element in this collection. Strict collections will apply f
to their elements immediately, while lazy collections like Views and LazyLists will only apply f
on each element if and when that element is evaluated, and each time that element is evaluated.
the return type of f
a function to apply to each element in this iterable collection
The same logical collection as this
Given a collection factory factory
, convert this collection to the appropriate representation for the current element type A
. Example uses:
xs.to(List) xs.to(ArrayBuffer) xs.to(BitSet) // for xs: Iterable[Int]
Convert collection to array.
This collection as an Iterable[A]
. No new collection will be built if this
is already an Iterable[A]
.
This collection as a Seq[A]
. This is equivalent to to(Seq)
but might be faster.
Creates a String representation of this object. The default representation is platform dependent. On the java platform it is the concatenation of the class name, "@", and the object's hashcode in hexadecimal.
a String representation of the object.
Transposes this iterable collection of iterable collections into a iterable collection of iterable collections.
The resulting collection's type will be guided by the static type of iterable collection. For example:
val xs = List( Set(1, 2, 3), Set(4, 5, 6)).transpose // xs == List( // List(1, 4), // List(2, 5), // List(3, 6)) val ys = Vector( List(1, 2, 3), List(4, 5, 6)).transpose // ys == Vector( // Vector(1, 4), // Vector(2, 5), // Vector(3, 6))
Note: Even when applied to a view or a lazy collection it will always force the elements.
the type of the elements of each iterable collection.
an implicit conversion which asserts that the element type of this iterable collection is an Iterable
.
a two-dimensional iterable collection of iterable collections which has as nth row the nth column of this iterable collection.
IllegalArgumentException
if all collections in this iterable collection are not of the same size.
Tries to extract a B
from an A
in a pattern matching expression.
Converts this iterable collection of pairs into two collections of the first and second half of each pair.
val xs = Iterable( (1, "one"), (2, "two"), (3, "three")).unzip // xs == (Iterable(1, 2, 3), // Iterable(one, two, three))
the type of the first half of the element pairs
the type of the second half of the element pairs
an implicit conversion which asserts that the element type of this iterable collection is a pair.
a pair of iterable collections, containing the first, respectively second half of each element pair of this iterable collection.
Converts this iterable collection of triples into three collections of the first, second, and third element of each triple.
val xs = Iterable( (1, "one", '1'), (2, "two", '2'), (3, "three", '3')).unzip3 // xs == (Iterable(1, 2, 3), // Iterable(one, two, three), // Iterable(1, 2, 3))
the type of the first member of the element triples
the type of the second member of the element triples
the type of the third member of the element triples
an implicit conversion which asserts that the element type of this iterable collection is a triple.
a triple of iterable collections, containing the first, second, respectively third member of each element triple of this iterable collection.
A copy of this immutable sequence with one single replaced element.
the element type of the returned immutable sequence.
the position of the replacement
the replacing element
a new immutable sequence which is a copy of this immutable sequence with the element at position index
replaced by elem
.
IndexOutOfBoundsException
if index
does not satisfy 0 <= index < length
. In case of a lazy collection this exception may be thrown at a later time or not at all (if the end of the collection is never evaluated).
A view over the elements of this collection.
Creates a non-strict filter of this iterable collection.
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.
Note: might return different results for different runs, unless the underlying collection type is ordered.
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 iterable collection which satisfy the predicate p
.
Returns a iterable collection formed from this iterable collection 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 iterable collection containing pairs consisting of corresponding elements of this iterable collection and that
. The length of the returned collection is the minimum of the lengths of this iterable collection and that
.
Returns a iterable collection formed from this iterable collection 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 iterable providing the second half of each result pair
the element to be used to fill up the result if this iterable collection is shorter than that
.
the element to be used to fill up the result if that
is shorter than this iterable collection.
a new collection of type That
containing pairs consisting of corresponding elements of this iterable collection and that
. The length of the returned collection is the maximum of the lengths of this iterable collection and that
. If this iterable collection is shorter than that
, thisElem
values are used to pad the result. If that
is shorter than this iterable collection, thatElem
values are used to pad the result.
Zips this iterable collection with its indices.
A new iterable collection containing pairs consisting of all elements of this iterable collection paired with their index. Indices start at 0
.
List("a", "b", "c").zipWithIndex == List(("a", 0), ("b", 1), ("c", 2))
Reuse: After calling this method, one should discard the iterator it was called on, and use only the iterator that was returned. Using the old iterator is undefined, subject to change, and may result in changes to the new iterator as well.
© 2002-2019 EPFL, with contributions from Lightbend.
Licensed under the Apache License, Version 2.0.
https://www.scala-lang.org/api/2.13.0/scala/collection/immutable/Range.html
The
Range
class represents integer values in range [start;end) with non-zero step valuestep
. It's a special case of an indexed sequence. For example:Ranges that contain more than
Int.MaxValue
elements can be created, but these overfull ranges have only limited capabilities. Any method that could require a collection of overInt.MaxValue
length to be created, or could be asked to index beyondInt.MaxValue
elements will throw an exception. Overfull ranges can safely be reduced in size by changing the step size (e.g.by 3
) or taking/dropping elements.contains
,equals
, and access to the ends of the range (head
,last
,tail
,init
) are also permitted on overfull ranges.