Selects all the elements of this sequence ignoring the duplicates as determined by == after applying the transforming function f.
Selects all the elements of this 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 sequence consisting of all the elements of this sequence without duplicates.
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.
Patching at negative indices is the same as patching starting at 0. Patching at indices at or larger than the length of the original sequence appends the patch to the end. If the replaced count would exceed the available elements, the difference in excess is ignored.
the element type of the returned sequence.
the index of the first replaced element
the replacement sequence
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 all the elements of other.
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 ord.compare) 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.
scala.math.Ordering Note: Even when applied to a view or a lazy collection it will always force the elements.
A copy of this sequence with one single replaced element.
A copy of this sequence with one single replaced element.
Type parametersthe element type of the returned sequence.
the replacing element
the position of the replacement
a new sequence which is a copy of this 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).
Alias for prependedAll.
Alias for prependedAll.
Alias for prepended.
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.
Alias for appended.
Note that :-ending operators are right associative (see example). A mnemonic for +: vs. :+ is: the COLon goes on the COLlection side.
Appends all elements of this collection to a string builder.
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.
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.
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 ending string.
the separator string.
the starting string.
the string builder b to which elements were appended.
A copy of this sequence with an element appended.
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.
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.
Type parametersthe 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.
Builds a new iterable collection by applying a partial function to all elements of this iterable collection on which the function is defined.
Builds a new iterable collection by applying a partial function to all elements of this iterable collection on which the function is defined.
Type parametersthe 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.
Finds the first element of the collection for which the given partial function is defined, and applies the partial function to it.
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.
Value parametersthe 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 of elements.
Iterates over combinations of elements.
A combination of length n is a sequence of n elements selected in order of their first index in this sequence.
For example, "xyx" has two combinations of length 2. The x is selected first: "xx", "xy". The sequence "yx" is not returned as a combination because it is subsumed by "xy".
If there is more than one way to generate the same combination, only one will be returned.
For example, the result "xy" arbitrarily selected one of the x elements.
As a further illustration, "xyxx" has three different ways to generate "xy" because there are three elements x to choose from. Moreover, there are three unordered pairs "xx" but only one is returned.
It is not specified which of these equal combinations is returned. It is an implementation detail that should not be relied on. For example, the combination "xx" does not necessarily contain the first x in this sequence. This behavior is observable if the elements compare equal but are not identical.
As a consequence, "xyx".combinations(3).next() is "xxy": the combination does not reflect the order of the original sequence, but the order in which elements were selected, by "first index"; the order of each x element is also arbitrary.
Note: Even when applied to a view or a lazy collection it will always force the elements.
AttributesAn Iterator which traverses the n-element combinations of this sequence.
Seq('a', 'b', 'b', 'b', 'c').combinations(2).foreach(println)
// List(a, b)
// List(a, c)
// List(b, b)
// List(b, c)
Seq('b', 'a', 'b').combinations(2).foreach(println)
// List(b, b)
// List(b, a)
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.
Type parametersthe element type of the returned collection.
the iterable to append.
a new sequence which contains all elements of this sequence followed by all elements of suffix.
Tests whether this sequence contains a given value as an element.
Tests whether this sequence contains a given value as an element.
Note: may not terminate for infinite-sized collections.
Value parametersthe 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.
Note: may not terminate for infinite-sized collections.
Value parametersthe 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.
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 maximal number of elements to copy.
the starting index of xs.
the array to fill.
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.
Copies elements to an array, returning the number of elements written.
Copies 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.
Type parametersthe type of the elements of the array.
the starting index of xs.
the array to fill.
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.
Copies elements to an array, returning the number of elements written.
Copies 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.
Type parametersthe type of the elements of the array.
the array to fill.
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.
Tests whether every element of this collection's iterator relates to the corresponding element of another collection by satisfying a test predicate.
Tests whether every element of this collection's iterator relates to the corresponding element of another collection by satisfying a test predicate.
Note: will not terminate for infinite-sized collections.
Type parametersthe type of the elements of that
the test predicate, which relates elements from both collections
the other collection
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
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.
Type parametersthe type of the elements of that
the test predicate, which relates elements from both sequences
the other sequence
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 collection which satisfy a predicate.
Counts the number of elements in the collection which satisfy a predicate.
Note: will not terminate for infinite-sized collections.
Value parametersthe predicate used to test elements.
the number of elements satisfying the predicate p.
Computes the multiset difference between this sequence and another sequence.
Computes the multiset difference between this sequence and another sequence.
Value parametersthe 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 sequence ignoring the duplicates.
Selects all the elements of this sequence ignoring the duplicates.
Attributesa new sequence consisting of all the elements of this sequence without duplicates.
Selects all elements except the first n ones.
Selects all elements except the first n ones.
Note: might return different results for different runs, unless the underlying collection type is ordered.
Value parametersthe number of elements to drop from this iterable collection.
a iterable collection consisting of all elements of this iterable collection except the first n ones, or else the empty iterable collection, if this iterable collection has less than n elements. If n is negative, don't drop any elements.
The rest of the collection without its n last elements.
The rest of the collection without its n last elements. For linear, immutable collections this should avoid making a copy.
Note: Even when applied to a view or a lazy collection it will always force the elements.
AttributesSelects all elements except the longest prefix that satisfies a predicate.
Selects all elements except the longest prefix that satisfies a predicate.
The matching prefix starts with the first element of this iterable collection, and the element following the prefix is the first element that does not satisfy the predicate. The matching prefix may be empty, so that this method returns the entire iterable collection.
Example:
scala> List(1, 2, 3, 100, 4).dropWhile(n => n < 10)
val res0: List[Int] = List(100, 4)
scala> List(1, 2, 3, 100, 4).dropWhile(n => n == 0)
val res1: List[Int] = List(1, 2, 3, 100, 4)
Use span to obtain both the prefix and suffix. Use filterNot to drop all elements that satisfy the predicate.
Note: might return different results for different runs, unless the underlying collection type is ordered.
Value parametersThe predicate used to test elements.
the longest suffix of this iterable collection whose first element does not satisfy the predicate p.
The empty iterable of the same type as this iterable
The empty iterable of the same type as this iterable
Attributesan empty iterable of type C.
Tests whether this sequence ends with the given sequence.
Tests whether this sequence ends with the given sequence.
Note: will not terminate for infinite-sized collections.
Value parametersthe sequence to test
true if this sequence has that as a suffix, false otherwise.
Tests whether a predicate holds for at least one element of this collection.
Tests whether a predicate holds for at least one element of this collection.
Note: may not terminate for infinite-sized collections.
Value parametersthe 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.
Selects all elements of this iterable collection which satisfy a predicate.
Value parametersthe predicate used to test elements.
a new iterable collection 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.
Selects all elements of this iterable collection which do not satisfy a predicate.
Value parametersthe 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.
Finds the first element of the collection satisfying a predicate, if any.
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.
Value parametersthe 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.
Finds the last element of the sequence satisfying a predicate, if any.
Note: will not terminate for infinite-sized collections.
Value parametersthe 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.
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.
Converts this iterable collection of iterable collections into a iterable collection formed by the elements of these iterable collections.
Converts this iterable collection of iterable collections into a iterable collection formed by the elements of these iterable 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 iterable collection.
an implicit conversion which asserts that the element type of this iterable collection is an Iterable.
a new iterable collection resulting from concatenating all element iterable collections.
Applies the given binary operator op to the given initial value z and all elements of this collection.
Applies the given binary operator op to the given initial value z and all elements of this collection.
For each application of the operator, each operand is either an element of this collection, the initial value, or another such application of the operator.
The order of applications of the operator is unspecified and may be nondeterministic. Each element appears exactly once in the computation. The initial value may be used an arbitrary number of times, but at least once.
If this collection is ordered, then for any application of the operator, the element(s) appearing in the left operand will precede those in the right.
Note: might return different results for different runs, unless either of the following conditions is met: (1) the operator is associative, and the underlying collection type is ordered; or (2) the operator is associative and commutative. In either case, it is also necessary that the initial value be a neutral value for the operator, e.g. Nil for List concatenation or 1 for multiplication.
The default implementation in IterableOnce is equivalent to foldLeft but may be overridden for more efficient traversal orders.
Note: will not terminate for infinite-sized collections.
Type parametersThe type parameter for the binary operator, a supertype of A.
A binary operator; must be associative for the result to always be the same across runs.
An initial value; may be used an arbitrary number of times in the computation of the result; must be a neutral value for op for the result to always be the same across runs.
The result of applying op between all the elements and z, or z if this collection is empty.
Applies the given binary operator op to the given initial value z and all elements of this collection, going left to right.
Applies the given binary operator op to the given initial value z and all elements of this collection, going left to right. Returns the initial value if this collection is empty.
"Going left to right" only makes sense if this collection is ordered: then if x1, x2, ..., xn are the elements of this collection, the result is op( op( ... op( op(z, x1), x2) ... ), xn).
If this collection is not ordered, then for each application of the operator, each right operand is an element. In addition, the leftmost operand is the initial value, and each other left operand is itself an application of the operator. The elements of this collection and the initial value all appear exactly once in the computation.
Note: might return different results for different runs, unless the underlying collection type is ordered.
Note: will not terminate for infinite-sized collections.
Type parametersThe result type of the binary operator.
A binary operator.
An initial value.
The result of applying op to z and all elements of this collection, going left to right. Returns z if this collection is empty.
Applies the given binary operator op to all elements of this collection and the given initial value z, going right to left.
Applies the given binary operator op to all elements of this collection and the given initial value z, going right to left. Returns the initial value if this collection is empty.
"Going right to left" only makes sense if this collection is ordered: then if x1, x2, ..., xn are the elements of this collection, the result is op(x1, op(x2, op( ... op(xn, z) ... ))).
If this collection is not ordered, then for each application of the operator, each left operand is an element. In addition, the rightmost operand is the initial value, and each other right operand is itself an application of the operator. The elements of this collection and the initial value all appear exactly once in the computation.
Note: might return different results for different runs, unless the underlying collection type is ordered.
Note: will not terminate for infinite-sized collections.
Type parametersThe result type of the binary operator.
A binary operator.
An initial value.
The result of applying op to all elements of this collection and z, going right to left. Returns z if this collection is empty.
Tests whether a predicate holds for all elements of this collection.
Tests whether a predicate holds for all elements of this collection.
Note: may not terminate for infinite-sized collections.
Value parametersthe 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.
Applies f to each element for its side effects.
Applies f to each element for its side effects. Note: U parameter needed to help scalac's type inference.
Partitions this iterable collection into a map of iterable collections according to some discriminator function.
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.
Type parametersthe 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.
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.
Type parametersthe type of values returned by the transformation function
the type of keys returned by the discriminator function
the element transformation function
the discriminator function
Partitions this iterable collection into a map according to a discriminator function key.
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 f 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.
AttributesPartitions elements in fixed size iterable collections.
Partitions elements in fixed size iterable collections.
Value parametersthe number of elements per group
An iterator producing iterable collections of size size, except the last will be less than size size if the elements don't divide evenly.
Selects the first element of this iterable collection.
Selects the first element of this iterable collection.
Note: might return different results for different runs, unless the underlying collection type is ordered.
Attributesthe first element of this iterable collection.
Optionally selects the first element.
Optionally selects the first element.
Note: might return different results for different runs, unless the underlying collection type is ordered.
Attributesthe 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 sequence.
Finds index of first occurrence of some value in this sequence.
Type parametersthe 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 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.
Type parametersthe type of the element elem.
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.
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.
Note: may not terminate for infinite-sized collections.
Value parametersthe 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 if no such subsequence 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.
Note: may not terminate for infinite-sized collections.
Value parametersthe start index
the sequence to test
the first index >= from such that the elements of this sequence starting at this index match the elements of sequence that, or -1 if no such subsequence exists.
Finds index of the first element satisfying some predicate.
Finds index of the first element satisfying some predicate.
Note: may not terminate for infinite-sized collections.
Value parametersthe 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.
Finds index of the first element satisfying some predicate after or at some start index.
Note: may not terminate for infinite-sized collections.
Value parametersthe start index
the predicate used to test elements.
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.
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.
Attributesa Range value from 0 to one less than the length of this sequence.
The initial part of the collection without its last element.
The initial part of the collection without its last element.
Note: Even when applied to a view or a lazy collection it will always force the elements.
AttributesIterates over the inits of this iterable collection.
Iterates over the inits of this iterable collection. The first value will be this iterable collection and the final one will be an empty iterable collection, 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.
Attributesan iterator over all the inits of this iterable collection
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.
Computes the multiset intersection between this sequence and another sequence.
Value parametersthe 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 the sequence is empty.
Tests whether the sequence is empty.
Note: The default implementation creates and discards an iterator.
Note: Implementations in subclasses that are not repeatedly iterable must take care not to consume any elements when isEmpty is called.
true if the sequence contains no elements, false otherwise.
Tests whether this iterable collection can be repeatedly traversed.
Tests whether this iterable collection can be repeatedly traversed. Always true for Iterables and false for Iterators unless overridden.
Attributestrue if it is repeatedly traversable, false otherwise.
The number of elements in this collection, if it can be cheaply computed, -1 otherwise.
The number of elements in this collection, if it can be cheaply computed, -1 otherwise. Cheaply usually means: Not requiring a collection traversal.
AttributesSelects the last element.
Selects the last element.
Note: might return different results for different runs, unless the underlying collection type is ordered.
AttributesThe last element of this iterable collection.
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.
Note: will not terminate for infinite-sized collections.
Type parametersthe type of the element elem.
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.
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.
Note: will not terminate for infinite-sized collections.
Value parametersthe 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 if no such subsequence 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.
Note: will not terminate for infinite-sized collections.
Value parametersthe end index
the sequence to test
the last index <= end such that the elements of this sequence starting at this index match the elements of sequence that, or -1 if no such subsequence exists.
Finds index of last element satisfying some predicate.
Finds index of last element satisfying some predicate.
Note: will not terminate for infinite-sized collections.
Value parametersthe 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.
Finds index of last element satisfying some predicate before or at given end index.
Note: will not terminate for infinite-sized collections.
Value parametersthe 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.
Optionally selects the last element.
Note: might return different results for different runs, unless the underlying collection type is ordered.
Attributesthe last element of this iterable collection$ if it is nonempty, None if it is empty.
Compares the length of this sequence to the size of another Iterable.
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.
Compares the length of this sequence to a test value.
Value parametersthe 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.
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
Builds a new iterable collection by applying a function to all elements of this iterable collection.
Builds a new iterable collection by applying a function to all elements of this iterable collection.
Type parametersthe element type of the returned iterable collection.
the function to apply to each element.
a new iterable collection resulting from applying the given function f to each element of this iterable collection and collecting the results.
Finds the largest element.
Finds the largest element.
Note: will not terminate for infinite-sized collections.
Type parametersThe type over which the ordering is defined.
An ordering to be used for comparing elements.
the largest element of this collection with respect to the ordering ord.
Finds the first element which yields the largest value measured by function f.
Finds the first element which yields the largest value measured by function f.
Note: will not terminate for infinite-sized collections.
Type parametersThe result type of the function f.
An ordering to be used for comparing elements.
The measuring function.
the first element of this collection with the largest value measured by function f with respect to the ordering cmp.
Finds the first element which yields the largest value measured by function f.
Finds the first element which yields the largest value measured by function f.
Note: will not terminate for infinite-sized collections.
Type parametersThe result type of the function f.
An ordering to be used for comparing elements.
The measuring function.
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.
Finds the largest element.
Note: will not terminate for infinite-sized collections.
Type parametersThe 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.
Finds the smallest element.
Note: will not terminate for infinite-sized collections.
Type parametersThe type over which the ordering is defined.
An ordering to be used for comparing elements.
the smallest element of this collection with respect to the ordering ord.
Finds the first element which yields the smallest value measured by function f.
Finds the first element which yields the smallest value measured by function f.
Note: will not terminate for infinite-sized collections.
Type parametersThe result type of the function f.
An ordering to be used for comparing elements.
The measuring function.
the first element of this collection with the smallest value measured by function f with respect to the ordering cmp.
Finds the first element which yields the smallest value measured by function f.
Finds the first element which yields the smallest value measured by function f.
Note: will not terminate for infinite-sized collections.
Type parametersThe result type of the function f.
An ordering to be used for comparing elements.
The measuring function.
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.
Finds the smallest element.
Note: will not terminate for infinite-sized collections.
Type parametersThe 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.
Displays all elements of this collection in a string.
Delegates to addString, which can be overridden.
Attributesa 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.
Displays all elements of this collection in a string using a separator string.
Delegates to addString, which can be overridden.
Value parametersthe 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.
Displays all elements of this collection in a string using start, end, and separator strings.
Delegates to addString, which can be overridden.
Value parametersthe ending string.
the separator string.
the starting 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)"
Tests whether the collection is not empty.
Tests whether the collection is not empty.
Attributestrue if the collection contains at least one element, false otherwise.
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.
Type parametersthe element type of the returned sequence.
the padding value
the target length
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.
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.
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.
Iterates over distinct permutations of elements.
Iterates over distinct permutations of elements.
Note: Even when applied to a view or a lazy collection it will always force the elements.
AttributesAn Iterator which traverses the distinct permutations of this sequence.
Seq('a', 'b', 'b').permutations.foreach(println)
// List(a, b, b)
// List(b, a, b)
// List(b, b, a)
A copy of the sequence with an element prepended.
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.
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 together the elements of this collection.
Multiplies together the elements of this collection.
The default implementation uses reduce for a known non-empty collection, foldLeft otherwise.
Note: will not terminate for infinite-sized collections.
Type parametersthe 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.
Applies the given binary operator op to all elements of this collection.
Applies the given binary operator op to all elements of this collection.
For each application of the operator, each operand is either an element of this collection or another such application of the operator. The order of applications of the operator is unspecified and may be nondeterministic. Each element appears exactly once in the computation.
If this collection is ordered, then for any application of the operator, the element(s) appearing in the left operand will precede those in the right.
Note: might return different results for different runs, unless either of the following conditions is met: (1) the operator is associative, and the underlying collection type is ordered; or (2) the operator is associative and commutative.
Note: will not terminate for infinite-sized collections.
Type parametersThe type parameter for the binary operator, a supertype of A.
A binary operator; must be associative for the result to always be the same across runs.
The result of applying op between all the elements if the collection is nonempty.
Applies the given binary operator op to all elements of this collection, going left to right.
Applies the given binary operator op to all elements of this collection, going left to right.
"Going left to right" only makes sense if this collection is ordered: then if x1, x2, ..., xn are the elements of this collection, the result is op( op( op( ... op(x1, x2) ... ), xn-1), xn).
If this collection is not ordered, then for each application of the operator, each right operand is an element. In addition, the leftmost operand is the first element of this collection and each other left operand is itself an application of the operator. Each element appears exactly once in the computation.
Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.
Note: will not terminate for infinite-sized collections.
Type parametersThe result type of the binary operator, a supertype of A.
A binary operator.
The result of applying op to all elements of this collection, going left to right.
If this collection is nonempty, reduces it with the given binary operator op, going left to right.
If this collection is nonempty, reduces it with the given binary operator op, going left to right.
The behavior is the same as reduceLeft except that the value is None if the collection is empty. Each element appears exactly once in the computation.
Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.
Note: will not terminate for infinite-sized collections.
Type parametersThe result type of the binary operator, a supertype of A.
A binary operator.
The result of reducing this collection with op going left to right if the collection is nonempty, inside a Some, and None otherwise.
If this collection is nonempty, reduces it with the given binary operator op.
If this collection is nonempty, reduces it with the given binary operator op.
The behavior is the same as reduce except that the value is None if the collection is empty. The order of applications of the operator is unspecified and may be nondeterministic. Each element appears exactly once in the computation.
Note: might return different results for different runs, unless either of the following conditions is met: (1) the operator is associative, and the underlying collection type is ordered; or (2) the operator is associative and commutative.
Note: will not terminate for infinite-sized collections.
Type parametersA type parameter for the binary operator, a supertype of A.
A binary operator; must be associative for the result to always be the same across runs.
The result of reducing this collection with op if the collection is nonempty, inside a Some, and None otherwise.
Applies the given binary operator op to all elements of this collection, going right to left.
Applies the given binary operator op to all elements of this collection, going right to left.
"Going right to left" only makes sense if this collection is ordered: then if x1, x2, ..., xn are the elements of this collection, the result is op(x1, op(x2, op( ... op(xn-1, xn) ... ))).
If this collection is not ordered, then for each application of the operator, each left operand is an element. In addition, the rightmost operand is the last element of this collection and each other right operand is itself an application of the operator. Each element appears exactly once in the computation.
Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.
Note: will not terminate for infinite-sized collections.
Type parametersThe result type of the binary operator, a supertype of A.
A binary operator.
The result of applying op to all elements of this collection, going right to left.
If this collection is nonempty, reduces it with the given binary operator op, going right to left.
If this collection is nonempty, reduces it with the given binary operator op, going right to left.
The behavior is the same as reduceRight except that the value is None if the collection is empty. Each element appears exactly once in the computation.
Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.
Note: will not terminate for infinite-sized collections.
Type parametersThe result type of the binary operator, a supertype of A.
A binary operator.
The result of reducing this collection with op going right to left if the collection is nonempty, inside a Some, and None otherwise.
Returns a new sequence with the elements of this sequence in reverse order.
Returns a new sequence with the elements of this sequence in reverse order.
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.
Attributesa new sequence with all elements of this sequence in reverse order.
An iterator yielding the elements of this sequence in reverse order.
An iterator yielding the elements of this sequence in reverse 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 reverse order.
Tests whether the elements of this collection are the same (and in the same order) as those of that.
Tests whether the elements of this collection are the same (and in the same order) as those of that.
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
the associative operator for the scan
neutral element for the operator op
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.
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.
Type parametersthe type of the elements in the resulting collection
the binary operator applied to the intermediate result and the element
the initial value
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.
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 binary operator applied to the intermediate result and the element
the initial value
collection with intermediate results
Searches within an interval in this sorted sequence for a specific element.
Searches 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 ordering to be used to compare elements.
the index following where the search ends.
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
Searches this sorted sequence for a specific element.
Searches 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.
Computes the length of the longest segment that starts from some index and whose elements all satisfy some predicate.
Computes the length of the longest segment that starts from some index and whose elements all satisfy some predicate.
Note: may not terminate for infinite-sized collections.
Value parametersthe index where the search starts.
the predicate used to test elements.
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 the length of the longest segment that starts from the first element and whose elements all satisfy some predicate.
Computes the length of the longest segment that starts from the first element and whose elements all satisfy some predicate.
Note: may not terminate for infinite-sized collections.
Value parametersthe predicate used to test elements.
the length of the longest segment of this sequence that starts from the first element such that every element of the segment satisfies the predicate p.
The size of this sequence.
The size of this sequence.
Note: will not terminate for infinite-sized collections.
Attributesthe number of elements in this sequence.
Compares the size of this sequence to the size of another Iterable.
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.
Compares the size of this sequence to a test value.
Value parametersthe 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.
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
Selects an interval of elements.
Selects an interval of elements. The returned iterable collection is made up of all elements x which satisfy the invariant:
from <= indexOf(x) < until
Note: might return different results for different runs, unless the underlying collection type is ordered.
Value parametersthe lowest index to include from this iterable collection.
the lowest index to EXCLUDE from this iterable collection.
a iterable collection containing the elements greater than or equal to index from extending up to (but not including) index until of this iterable collection.
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 returned iterator will be empty when called on an empty collection. The last element the iterator produces may be smaller than the window size when the original collection isn't exhausted by the window before it and its last element isn't skipped by the step before it.
Value parametersthe 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 smaller if there are fewer than size elements remaining to be grouped.
List(1, 2, 3, 4, 5).sliding(2, 2) = Iterator(List(1, 2), List(3, 4), List(5))
List(1, 2, 3, 4, 5, 6).sliding(2, 3) = Iterator(List(1, 2), List(4, 5))
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.)
An empty collection returns an empty iterator, and a non-empty collection containing fewer elements than the window size returns an iterator that will produce the original collection as its only element.
Value parametersthe number of elements per group
An iterator producing iterable collections of size size, except for a non-empty collection with less than size elements, which returns an iterator that produces the source collection itself as its only element.
List().sliding(2) = empty iterator
List(1).sliding(2) = Iterator(List(1))
List(1, 2).sliding(2) = Iterator(List(1, 2))
List(1, 2, 3).sliding(2) = Iterator(List(1, 2), List(2, 3))
Sorts this sequence according to the Ordering which results from transforming an implicitly given Ordering with a transformation function.
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.
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 (lt returns false for both directions of comparison) appear in the same order in the sorted sequence as in the original.
a predicate that is true if its first argument strictly 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", "Bobby", "Tom", "John", "Bob").sortWith((x, y) => x.take(3).compareTo(y.take(3)) < 0) =
List("Bobby", "Bob", "John", "Steve", "Tom")
Splits this iterable collection into a prefix/suffix pair according to a predicate.
Splits this iterable collection 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.
Note: might return different results for different runs, unless the underlying collection type is ordered.
Value parametersthe test predicate
a pair consisting of the longest prefix of this iterable collection whose elements all satisfy p, and the rest of this iterable collection.
Splits this iterable collection into a prefix/suffix pair at a given position.
Splits this iterable collection 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).
Note: might return different results for different runs, unless the underlying collection type is ordered.
Value parametersthe position at which to split.
a pair of iterable collections consisting of the first n elements of this iterable collection, 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 index where the sequence is searched.
the sequence to test
true if the sequence that is contained in this sequence at index offset, otherwise false.
Returns a scala.collection.Stepper for the elements of this collection.
Returns a scala.collection.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 scala.collection.StepperShape parameter defines the resulting Stepper type according to the element type of this collection.
For collections of Int, Short, Byte or Char, an scala.collection.IntStepper is returned
For collections of Double or Float, a scala.collection.DoubleStepper is returned
For collections of Long a scala.collection.LongStepper is returned
For any other element type, an scala.collection.AnyStepper is returned
Note that this method is overridden in subclasses and the return type is refined to S with EfficientSplit, for example scala.collection.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.
Sums the elements of this collection.
Sums the elements of this collection.
The default implementation uses reduce for a known non-empty collection, foldLeft otherwise.
Note: will not terminate for infinite-sized collections.
Type parametersthe 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 collection with respect to the + operator in num.
The rest of the collection without its first element.
Iterates over the tails of this iterable collection.
Iterates over the tails of this iterable collection. The first value will be this iterable collection and the final one will be an empty iterable collection, with the intervening values the results of successive applications of tail.
an iterator over all the tails of this iterable collection
List(1,2,3).tails = Iterator(List(1,2,3), List(2,3), List(3), Nil)
Selects the first n elements.
Selects the first n elements.
Note: might return different results for different runs, unless the underlying collection type is ordered.
Value parametersthe number of elements to take from this iterable collection.
a iterable collection consisting only of the first n elements of this iterable collection, or else the whole iterable collection, if it has less than n elements. If n is negative, returns an empty iterable collection.
A collection containing the last n elements of this collection.
Takes longest prefix of elements that satisfy a predicate.
Takes longest prefix of elements that satisfy a predicate.
Note: might return different results for different runs, unless the underlying collection type is ordered.
Value parametersThe predicate used to test elements.
the longest prefix of this iterable collection whose elements all satisfy the predicate p.
Applies a side-effecting function to each element in this collection.
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, converts this collection to the appropriate representation for the current element type A.
Given a collection factory factory, converts 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]
Converts this collection to an Array.
Converts this collection to an Array.
Implementation note: DO NOT call Array.from from this method.
Type parametersThe type of elements of the result, a supertype of A.
This collection as an Array[B].
Converts this collection to a Buffer.
Converts this collection to a Buffer.
The type of elements of the result, a supertype of A.
This collection as a Buffer[B].
Converts this collection to an IndexedSeq.
Converts this collection to a List.
Converts this collection to a Map, given an implicit coercion from the collection's type to a key-value tuple.
Converts this collection to a Map, given an implicit coercion from the collection's type to a key-value tuple.
The key type for the resulting map.
The value type for the resulting map.
An implicit coercion from A to [K, V].
This collection as a Map[K, V].
Converts this collection to a Set.
Converts this collection to a Set.
The type of elements of the result, a supertype of A.
This collection as a Set[B].
Converts this collection to a Vector.
Transposes this iterable collection of iterable collections into a iterable collection of iterable collections.
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.
Type parametersthe 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.
Converts this iterable collection of pairs into two collections of the first and second half of each pair.
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.
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 view over the elements of this collection.
A view over the elements of this collection.
AttributesCreates a non-strict filter of this iterable 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.
Value parametersthe 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.
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.
Type parametersthe 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.
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.
Value parametersthe iterable providing the second half of each result pair
the element to be used to fill up the result if that is shorter than this iterable collection.
the element to be used to fill up the result if this iterable collection is shorter than that.
a new collection of the type of this iterable collection 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.
Zips this iterable collection with its indices.
AttributesA 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))
Gets the element at the specified index.
Gets 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.
The companion object of this iterable collection, providing various factory methods.
The companion object of this iterable collection, providing various factory methods.
AttributesWhen 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).
The length (number of elements) of the sequence.
The length (number of elements) of the sequence. size is an alias for length in Seq collections.
Aggregates the results of applying an operator to subsequent elements.
Aggregates the results of applying an operator to subsequent elements.
Since this method degenerates to foldLeft for sequential (non-parallel) collections, where the combining operation is ignored, it is advisable to prefer foldLeft for that case.
For parallel collections, use the aggregate method specified by scala.collection.parallel.ParIterableLike.
the result type, produced by seqop, combop, and by this function as a final result.
an associative operator for combining sequential results, unused for sequential collections.
the binary operator used to accumulate the result.
the start value, a neutral element for seqop.
[Since version 2.13.0] For sequential collections, prefer `foldLeft(z)(seqop)`. For parallel collections, use `ParIterableLike#aggregate`.
Tests whether this collection is known to have a finite size.
Tests whether this collection 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. Non-empty Iterators usually return false even if they were created from a collection with a known finite size.
Note: many collection methods will not work on collections of infinite sizes. The typical failure mode is an infinite loop. These methods always attempt a traversal without checking first that hasDefiniteSize returns true. However, checking hasDefiniteSize can provide an assurance that size is well-defined and non-termination is not a concern.
true if this collection is known to have finite size, false otherwise.
method knownSize for a more useful alternative
[Since version 2.13.0] Check .knownSize instead of .hasDefiniteSize for more actionable information (see scaladoc for details)
This method is deprecated in 2.13 because it does not provide any actionable information. As noted above, even the collection library itself does not use it. When there is no guarantee that a collection is finite, it is generally best to attempt a computation anyway and document that it will not terminate for infinite collections rather than backing out because this would prevent performing the computation on collections that are in fact finite even though hasDefiniteSize returns false.
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.
Note: may not terminate for infinite-sized collections.
Value parametersthe 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.
[Since version 2.13.0] Use segmentLength instead of prefixLength
[Since version 2.13.0] Use coll instead of repr in a collection implementation, use the collection value itself from the outside
[Since version 2.13.0] Use .reverseIterator.map(f).to(...) instead of .reverseMap(f)
This collection as an Iterable[A]. No new collection will be built if this is already an Iterable[A].
[Since version 2.13.7] toIterable is internal and will be made protected; its name is similar to `toList` or `toSeq`, but it doesn\'t copy non-immutable collections
Converts this iterable collection to an unspecified Iterable.
Converts this iterable collection to an unspecified Iterable. Will return the same collection if this instance is already Iterable.
AttributesAn Iterable containing all elements of this iterable collection.
[Since version 2.13.0] toTraversable is internal and will be made protected; its name is similar to `toList` or `toSeq`, but it doesn\'t copy non-immutable collections
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.
the element type of the returned sequence.
the sequence to add.
a new collection which contains all elements of this sequence followed by all elements of that.
[Since version 2.13.0] Use `concat` instead
A view over a slice of the elements of this collection.
A view over a slice of the elements of this collection.
Attributes[Since version 2.13.0] Use .view.slice(from, until) instead of .view(from, until)
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