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 ==
Returns a new mutable indexed sequence containing the elements from the left hand operand followed by the elements from the right hand operand. The element type of the mutable indexed sequence is the most specific superclass encompassing the element types of the two operands.
the element type of the returned collection.
the class of the returned collection. Where possible, That is the same class as the current collection class Repr, but this depends on the element type B being admissible for that class, which means that an implicit instance of type CanBuildFrom[Repr, B, That] is found.
the traversable to append.
an implicit value of class CanBuildFrom which determines the result class That from the current representation type Repr and the new element type B.
a new collection of type That which contains all elements of this mutable indexed sequence followed by all elements of that.
As with ++, returns a new collection containing the elements from the left operand followed by the elements from the right operand.
It differs from ++ in that the right operand determines the type of the resulting collection rather than the left one. Mnemonic: the COLon is on the side of the new COLlection type.
Example:
scala> val x = List(1) x: List[Int] = List(1) scala> val y = LinkedList(2) y: scala.collection.mutable.LinkedList[Int] = LinkedList(2) scala> val z = x ++: y z: scala.collection.mutable.LinkedList[Int] = LinkedList(1, 2)
This overload exists because: for the implementation of ++: we should reuse that of ++ because many collections override it with more efficient versions.
Since TraversableOnce has no ++ method, we have to implement that directly, but Traversable and down can use the overload.
the element type of the returned collection.
the class of the returned collection. Where possible, That is the same class as the current collection class Repr, but this depends on the element type B being admissible for that class, which means that an implicit instance of type CanBuildFrom[Repr, B, That] is found.
the traversable to append.
an implicit value of class CanBuildFrom which determines the result class That from the current representation type Repr and the new element type B.
a new collection of type That which contains all elements of this mutable indexed sequence followed by all elements of that.
As with ++, returns a new collection containing the elements from the left operand followed by the elements from the right operand.
It differs from ++ in that the right operand determines the type of the resulting collection rather than the left one. Mnemonic: the COLon is on the side of the new COLlection type.
Example:
scala> val x = List(1) x: List[Int] = List(1) scala> val y = LinkedList(2) y: scala.collection.mutable.LinkedList[Int] = LinkedList(2) scala> val z = x ++: y z: scala.collection.mutable.LinkedList[Int] = LinkedList(1, 2)
the element type of the returned collection.
the traversable to append.
a new array which contains all elements of this array followed by all elements of that.
A copy of the array with an element prepended.
Note that :-ending operators are right associative (see example). A mnemonic for +: vs. :+ is: the COLon goes on the COLlection side.
Also, the original array 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 prepended element
a new array consisting of elem followed by all elements of this array.
Applies a binary operator to a start value and all elements of this mutable indexed sequence, going left to right.
Note: /: is alternate syntax for foldLeft; z /: xs is the same as xs foldLeft z.
Examples:
Note that the folding function used to compute b is equivalent to that used to compute c.
scala> val a = List(1,2,3,4) a: List[Int] = List(1, 2, 3, 4) scala> val b = (5 /: a)(_+_) b: Int = 15 scala> val c = (5 /: a)((x,y) => x + y) c: Int = 15
the result type of the binary operator.
the start value.
the binary operator.
the result of inserting op between consecutive elements of this mutable indexed sequence, going left to right with the start value z on the left:
op(...op(op(z, x_1), x_2), ..., x_n)
where x1, ..., xn are the elements of this mutable indexed sequence.
A copy of this array with an element appended.
A mnemonic for +: vs. :+ is: the COLon goes on the COLlection side.
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 appended element
a new array consisting of all elements of this array followed by elem.
Applies a binary operator to all elements of this mutable indexed sequence and a start value, going right to left.
Note: :\ is alternate syntax for foldRight; xs :\ z is the same as xs foldRight z.
Examples:
Note that the folding function used to compute b is equivalent to that used to compute c.
scala> val a = List(1,2,3,4) a: List[Int] = List(1, 2, 3, 4) scala> val b = (a :\ 5)(_+_) b: Int = 15 scala> val c = (a :\ 5)((x,y) => x + y) c: Int = 15
the result type of the binary operator.
the start value
the binary operator
the result of inserting op between consecutive elements of this mutable indexed sequence, going right to left with the start value z on the right:
op(x_1, op(x_2, ... op(x_n, z)...))
where x1, ..., xn are the elements of this mutable indexed sequence.
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 mutable indexed sequence to a string builder. The written text consists of the string representations (w.r.t. the method toString) of all elements of this mutable indexed sequence 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 mutable indexed sequence to a string builder using a separator string. The written text consists of the string representations (w.r.t. the method toString) of all elements of this mutable indexed sequence, 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 mutable indexed sequence to a string builder using start, end, and separator strings. The written text begins with the string start and ends with the string end. Inside, the string representations (w.r.t. the method toString) of all elements of this mutable indexed sequence 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.
Aggregates the results of applying an operator to subsequent elements.
This is a more general form of fold and reduce. It is similar to foldLeft in that it doesn't require the result to be a supertype of the element type. In addition, it allows parallel collections to be processed in chunks, and then combines the intermediate results.
aggregate splits the mutable indexed sequence into partitions and processes each partition by sequentially applying seqop, starting with z (like foldLeft). Those intermediate results are then combined by using combop (like fold). The implementation of this operation may operate on an arbitrary number of collection partitions (even 1), so combop may be invoked an arbitrary number of times (even 0).
As an example, consider summing up the integer values of a list of chars. The initial value for the sum is 0. First, seqop transforms each input character to an Int and adds it to the sum (of the partition). Then, combop just needs to sum up the intermediate results of the partitions:
List('a', 'b', 'c').aggregate(0)({ (sum, ch) => sum + ch.toInt }, { (p1, p2) => p1 + p2 })
the type of accumulated results
the initial value for the accumulated result of the partition - this will typically be the neutral element for the seqop operator (e.g. Nil for list concatenation or 0 for summation) and may be evaluated more than once
an operator used to accumulate results within a partition
an associative operator used to combine results from different partitions
The element at given index.
Indices start at 0; xs.apply(0) is the first element of array xs. Note the indexing syntax xs(i) is a shorthand for xs.apply(i).
the index
the element at the given index
ArrayIndexOutOfBoundsException if i < 0 or length <= i
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.
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 mutable indexed sequence should be compared
true, if this mutable indexed sequence can possibly equal that, false otherwise. The test takes into consideration only the run-time types of objects but ignores their elements.
Builds a new collection by applying a partial function to all elements of this array on which the function is defined.
the element type of the returned collection.
the partial function which filters and maps the array.
a new array 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 mutable indexed sequence for which the given partial function is defined, and applies the partial function to it.
the partial function
an option value containing pf applied to the first value for which it is defined, or None if none exists.
Seq("a", 1, 5L).collectFirst({ case x: Int => x*10 }) = Some(10)
Iterates over combinations. 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.
An Iterator which traverses the possible n-element combinations of this mutable indexed sequence.
"abbbc".combinations(2) = Iterator(ab, ac, bb, bc)
Tests whether this mutable indexed sequence contains a given value as an element.
the element to test.
true if this mutable indexed sequence has an element that is equal (as determined by ==) to elem, false otherwise.
Tests whether this mutable indexed sequence contains a given sequence as a slice.
the sequence to test
true if this mutable indexed sequence contains a slice with the same elements as that, otherwise false.
Copies the elements of this array to an array. Fills the given array xs with at most len elements of this array, starting at position start. Copying will stop once either the end of the current array is reached, or the end of the target array is reached, or len elements have been copied.
the array to fill.
the starting index.
the maximal number of elements to copy.
Copies the elements of this array to an array. Fills the given array xs with values of this array. Copying will stop once either the end of the current array is reached, or the end of the target array is reached.
the array to fill.
Copies the elements of this array to an array. Fills the given array xs with values of this array, beginning at index start. Copying will stop once either the end of the current array is reached, or the end of the target array is reached.
the array to fill.
the starting index.
Copies all elements of this mutable indexed sequence to a buffer.
The buffer to which elements are copied.
Tests whether every element of this mutable indexed 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 mutable indexed sequence and y of that, otherwise false.
Counts the number of elements in the mutable indexed sequence which satisfy a predicate.
the predicate used to test elements.
the number of elements satisfying the predicate p.
Creates a possible nested IndexedSeq which consists of all the elements of this array. If the elements are arrays themselves, the deep transformation is applied recursively to them. The stringPrefix of the IndexedSeq is "Array", hence the IndexedSeq prints like an array with all its elements shown, and the same recursively for any subarrays.
Example:
Array(Array(1, 2), Array(3, 4)).deep.toString
prints: Array(Array(1, 2), Array(3, 4))
An possibly nested indexed sequence of consisting of all the elements of the array.
Computes the multiset difference between this array and another sequence.
the sequence of elements to remove
a new array which contains all elements of this array except some of occurrences of elements that also appear in that. If an element value x appears n times in that, then the first n occurrences of x will not form part of the result, but any following occurrences will.
Builds a new mutable indexed sequence from this mutable indexed sequence without any duplicate elements.
A new mutable indexed sequence which contains the first occurrence of every element of this mutable indexed sequence.
Selects all elements except first n ones.
the number of elements to drop from this mutable indexed sequence.
a mutable indexed sequence consisting of all elements of this mutable indexed sequence except the first n ones, or else the empty mutable indexed sequence, if this mutable indexed sequence has less than n elements. If n is negative, don't drop any elements.
Selects all elements except last n ones.
The number of elements to take
a mutable indexed sequence consisting of all elements of this mutable indexed sequence except the last n ones, or else the empty mutable indexed sequence, if this mutable indexed sequence has less than n elements.
Drops longest prefix of elements that satisfy a predicate.
the longest suffix of this mutable indexed sequence whose first element does not satisfy the predicate p.
Tests whether this mutable indexed sequence ends with the given sequence.
the sequence to test
true if this mutable indexed 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 equality method for reference types. Default implementation delegates to eq.
See also equals in scala.Any.
true if the receiver object is equivalent to the argument; false otherwise.
Tests whether a predicate holds for at least one element of this mutable indexed sequence.
the predicate used to test elements.
false if this mutable indexed sequence is empty, otherwise true if the given predicate p holds for some of the elements of this mutable indexed sequence, otherwise false
Selects all elements of this mutable indexed sequence which satisfy a predicate.
the predicate used to test elements.
a new mutable indexed sequence consisting of all elements of this mutable indexed sequence that satisfy the given predicate p. The order of the elements is preserved.
Selects all elements of this mutable indexed sequence which do not satisfy a predicate.
the predicate used to test elements.
a new mutable indexed sequence consisting of all elements of this mutable indexed sequence that do not satisfy the given predicate p. The order of the elements is 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.
not specified by SLS as a member of AnyRef
Finds the first element of the mutable indexed sequence satisfying a predicate, if any.
the predicate used to test elements.
an option value containing the first element in the mutable indexed sequence that satisfies p, or None if none exists.
Builds a new collection by applying a function to all elements of this array 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 array. This might cause unexpected results sometimes. For example:
// lettersOf will return a Seq[Char] of likely repeated letters, instead of a Set
def lettersOf(words: Seq[String]) = words flatMap (word => word.toSet)
// lettersOf will return a Set[Char], not a Seq
def lettersOf(words: Seq[String]) = words.toSet flatMap (word => word.toSeq)
// xs will be an Iterable[Int]
val xs = Map("a" -> List(11,111), "b" -> List(22,222)).flatMap(_._2)
// ys will be a Map[Int, Int]
val ys = Map("a" -> List(1 -> 11,1 -> 111), "b" -> List(2 -> 22,2 -> 222)).flatMap(_._2)
the element type of the returned collection.
the function to apply to each element.
a new array resulting from applying the given collection-valued function f to each element of this array and concatenating the results.
Flattens a two-dimensional array by concatenating all its rows into a single array.
Type of row elements.
A function that converts elements of this array to rows - arrays of type U.
An array obtained by concatenating rows of this array.
Folds the elements of this mutable indexed sequence using the specified associative binary operator.
The order in which operations are performed on elements is unspecified and may be nondeterministic.
a type parameter for the binary operator, a supertype of A.
a neutral element for the fold operation; may be added to the result an arbitrary number of times, and must not change the result (e.g., Nil for list concatenation, 0 for addition, or 1 for multiplication).
a binary operator that must be associative.
the result of applying the fold operator op between all the elements and z, or z if this mutable indexed sequence is empty.
Applies a binary operator to a start value and all elements of this mutable indexed sequence, going left to right.
the result type of the binary operator.
the start value.
the binary operator.
the result of inserting op between consecutive elements of this mutable indexed sequence, going left to right with the start value z on the left:
op(...op(z, x_1), x_2, ..., x_n)
where x1, ..., xn are the elements of this mutable indexed sequence. Returns z if this mutable indexed sequence is empty.
Applies a binary operator to all elements of this mutable indexed sequence and a start value, going right to left.
the result type of the binary operator.
the start value.
the binary operator.
the result of inserting op between consecutive elements of this mutable indexed sequence, going right to left with the start value z on the right:
op(x_1, op(x_2, ... op(x_n, z)...))
where x1, ..., xn are the elements of this mutable indexed sequence. Returns z if this mutable indexed sequence is empty.
Tests whether a predicate holds for all elements of this mutable indexed sequence.
the predicate used to test elements.
true if this mutable indexed sequence is empty or the given predicate p holds for all elements of this mutable indexed sequence, otherwise false.
Applies a function f to all elements of this array.
Note: this method underlies the implementation of most other bulk operations. Subclasses should re-implement this method if a more efficient implementation exists.
the function that is applied for its side-effect to every element. The result of function f is discarded.
Returns string formatted according to given format string. Format strings are as for String.format (@see java.lang.String.format).
Returns the runtime class representation of the object.
a class object corresponding to the runtime type of the receiver.
Partitions this mutable indexed sequence into a map of mutable indexed sequences according to some discriminator function.
Note: this method is not re-implemented by views. This means when applied to a view it will always force the view and return a new mutable indexed sequence.
the type of keys returned by the discriminator function.
the discriminator function.
A map from keys to mutable indexed sequences 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 mutable indexed sequence of those elements x for which f(x) equals k.
Partitions elements in fixed size mutable indexed sequences.
the number of elements per group
An iterator producing mutable indexed sequences of size size, except the last will be less than size size if the elements don't divide evenly.
scala.collection.Iterator, method grouped
Tests whether this mutable indexed sequence is known to have a finite size. All strict collections are known to have finite size. For a non-strict collection such as Stream, the predicate returns true if all elements have been computed. It returns false if the stream is not yet evaluated to the end. 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.
The hashCode method for reference types. See hashCode in scala.Any.
the hash code value for this object.
Selects the first element of this mutable indexed sequence.
the first element of this mutable indexed sequence.
NoSuchElementException if the mutable indexed sequence is empty.
Optionally selects the first element.
the first element of this mutable indexed sequence if it is nonempty, None if it is empty.
Finds index of first occurrence of some value in this array after or at some start index.
the element value to search for.
the start index
the index >= from of the first element of this array that is equal (as determined by ==) to elem, or -1, if none exists.
Finds index of first occurrence of some value in this array.
the element value to search for.
the index of the first element of this array that is equal (as determined by ==) to elem, or -1, if none exists.
Finds first index after or at a start index where this mutable indexed sequence contains a given sequence as a slice.
the sequence to test
the start index
the first index >= from such that the elements of this mutable indexed sequence starting at this index match the elements of sequence that, or -1 of no such subsequence exists.
Finds first index where this mutable indexed sequence contains a given sequence as a slice.
the sequence to test
the first index such that the elements of this mutable indexed sequence starting at this index match the elements of sequence that, or -1 of no such subsequence exists.
Finds index of the first element satisfying some predicate after or at some start index.
the predicate used to test elements.
the start index
the index >= from of the first element of this mutable indexed sequence that satisfies the predicate p, or -1, if none exists.
Finds index of first element satisfying some predicate.
the predicate used to test elements.
the index of the first element of this mutable indexed sequence that satisfies the predicate p, or -1, if none exists.
Produces the range of all indices of this sequence.
a Range value from 0 to one less than the length of this mutable indexed sequence.
Selects all elements except the last.
a mutable indexed sequence consisting of all elements of this mutable indexed sequence except the last one.
UnsupportedOperationException if the mutable indexed sequence is empty.
Iterates over the inits of this mutable indexed sequence. The first value will be this mutable indexed sequence and the final one will be an empty mutable indexed sequence, with the intervening values the results of successive applications of init.
an iterator over all the inits of this mutable indexed sequence
List(1,2,3).inits = Iterator(List(1,2,3), List(1,2), List(1), Nil)
Computes the multiset intersection between this array and another sequence.
the sequence of elements to intersect with.
a new array which contains all elements of this array 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 mutable indexed 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 mutable indexed sequence contains an element at position idx, false otherwise.
Tests whether this mutable indexed sequence is empty.
true if the mutable indexed sequence contain 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 mutable indexed sequence can be repeatedly traversed.
true
Creates a new iterator over all elements contained in this iterable object.
the new iterator
Selects the last element.
The last element of this mutable indexed sequence.
NoSuchElementException If the mutable indexed sequence is empty.
Finds index of last occurrence of some value in this array before or at a given end index.
the element value to search for.
the end index.
the index <= end of the last element of this array that is equal (as determined by ==) to elem, or -1, if none exists.
Finds index of last occurrence of some value in this array.
the element value to search for.
the index of the last element of this array that is equal (as determined by ==) to elem, or -1, if none exists.
Finds last index before or at a given end index where this mutable indexed sequence contains a given sequence as a slice.
the sequence to test
the end index
the last index <= end such that the elements of this mutable indexed sequence starting at this index match the elements of sequence that, or -1 of no such subsequence exists.
Finds last index where this mutable indexed sequence contains a given sequence as a slice.
the sequence to test
the last index such that the elements of this mutable indexed sequence starting a this index match the elements of sequence that, or -1 of no such subsequence exists.
Finds index of last element satisfying some predicate before or at given end index.
the predicate used to test elements.
the index <= end of the last element of this mutable indexed sequence that satisfies the predicate p, or -1, if none exists.
Finds index of last element satisfying some predicate.
the predicate used to test elements.
the index of the last element of this mutable indexed sequence that satisfies the predicate p, or -1, if none exists.
Optionally selects the last element.
the last element of this mutable indexed sequence$ if it is nonempty, None if it is empty.
Compares the length of this mutable indexed sequence to a test value.
the test value that gets compared with the length.
A value x where
x < 0 if this.length < len x == 0 if this.length == len x > 0 if this.length > len
The method as implemented here does not call length directly; its running time is O(length min len) instead of O(length). The method should be overwritten if computing length is cheap.
Builds a new collection by applying a function to all elements of this array.
the element type of the returned collection.
the function to apply to each element.
a new array resulting from applying the given function f to each element of this array and collecting the results.
Finds the largest element.
the largest element of this array.
UnsupportedOperationException if this array 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.
the first element of this array with the largest value measured by function f.
UnsupportedOperationException if this array is empty.
Finds the smallest element.
the smallest element of this array
UnsupportedOperationException if this array 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.
the first element of this array with the smallest value measured by function f.
UnsupportedOperationException if this array is empty.
Displays all elements of this mutable indexed sequence in a string.
a string representation of this mutable indexed sequence. In the resulting string the string representations (w.r.t. the method toString) of all elements of this mutable indexed sequence follow each other without any separator string.
Displays all elements of this mutable indexed sequence in a string using a separator string.
the separator string.
a string representation of this mutable indexed sequence. In the resulting string the string representations (w.r.t. the method toString) of all elements of this mutable indexed sequence are separated by the string sep.
List(1, 2, 3).mkString("|") = "1|2|3"
Displays all elements of this mutable indexed sequence in a string using start, end, and separator strings.
the starting string.
the separator string.
the ending string.
a string representation of this mutable indexed sequence. The resulting string begins with the string start and ends with the string end. Inside, the string representations (w.r.t. the method toString) of all elements of this mutable indexed sequence 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.
Tests whether the mutable indexed sequence is not empty.
true if the mutable indexed sequence 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
A copy of this array with an element value appended until a given target length is reached.
the target length
the padding value
a new array consisting of all elements of this array followed by the minimal number of occurrences of elem so that the resulting array has a length of at least len.
Returns a parallel implementation of this collection.
For most collection types, this method creates a new parallel collection by copying all the elements. For these collection, par takes linear time. Mutable collections in this category do not produce a mutable parallel collection that has the same underlying dataset, so changes in one collection will not be reflected in the other one.
Specific collections (e.g. ParArray or mutable.ParHashMap) override this default behaviour by creating a parallel collection which shares the same underlying dataset. For these collections, par takes constant or sublinear time.
All parallel collections return a reference to themselves.
a parallel implementation of this collection
Partitions this mutable indexed sequence in two mutable indexed sequences according to a predicate.
the predicate on which to partition.
a pair of mutable indexed sequences: the first mutable indexed sequence consists of all elements that satisfy the predicate p and the second mutable indexed sequence consists of all elements that don't. The relative order of the elements in the resulting mutable indexed sequences is the same as in the original mutable indexed sequence.
Produces a new array where a slice of elements in this array is replaced by another sequence.
the index of the first replaced element
the number of elements to drop in the original array
a new array consisting of all elements of this array except that replaced elements starting from from are replaced by patch.
Iterates over distinct permutations.
An Iterator which traverses the distinct permutations of this mutable indexed sequence.
"abb".permutations = Iterator(abb, bab, bba)
Returns the length of the longest prefix whose elements all satisfy some predicate.
the predicate used to test elements.
the length of the longest prefix of this mutable indexed sequence such that every element of the segment satisfies the predicate p.
Multiplies up the elements of this collection.
the product of all elements in this array of numbers of type Int. Instead of Int, any other type T with an implicit Numeric[T] implementation can be used as element type of the array and as result type of product. Examples of such types are: Long, Float, Double, BigInt.
Reduces the elements of this mutable indexed sequence using the specified associative binary operator.
The order in which operations are performed on elements is unspecified and may be nondeterministic.
A type parameter for the binary operator, a supertype of A.
A binary operator that must be associative.
The result of applying reduce operator op between all the elements if the mutable indexed sequence is nonempty.
UnsupportedOperationException if this mutable indexed sequence is empty.
Applies a binary operator to all elements of this mutable indexed sequence, going left to right.
the result type of the binary operator.
the binary operator.
the result of inserting op between consecutive elements of this mutable indexed sequence, going left to right:
op( op( ... op(x_1, x_2) ..., x_{n-1}), x_n)
where x1, ..., xn are the elements of this mutable indexed sequence.
UnsupportedOperationException if this mutable indexed sequence is empty.
Optionally applies a binary operator to all elements of this mutable indexed sequence, going left to right.
the result type of the binary operator.
the binary operator.
an option value containing the result of reduceLeft(op) if this mutable indexed sequence is nonempty, None otherwise.
Reduces the elements of this mutable indexed sequence, if any, using the specified associative binary operator.
The order in which operations are performed on elements is unspecified and may be nondeterministic.
A type parameter for the binary operator, a supertype of A.
A binary operator that must be associative.
An option value containing result of applying reduce operator op between all the elements if the collection is nonempty, and None otherwise.
Applies a binary operator to all elements of this mutable indexed sequence, going right to left.
the result type of the binary operator.
the binary operator.
the result of inserting op between consecutive elements of this mutable indexed sequence, going right to left:
op(x_1, op(x_2, ..., op(x_{n-1}, x_n)...))
where x1, ..., xn are the elements of this mutable indexed sequence.
UnsupportedOperationException if this mutable indexed sequence is empty.
Optionally applies a binary operator to all elements of this mutable indexed sequence, going right to left.
the result type of the binary operator.
the binary operator.
an option value containing the result of reduceRight(op) if this mutable indexed sequence is nonempty, None otherwise.
The collection of type mutable indexed sequence underlying this TraversableLike object. By default this is implemented as the TraversableLike object itself, but this can be overridden.
Returns new mutable indexed sequence with elements in reversed order.
A new mutable indexed sequence with all elements of this mutable indexed sequence in reversed order.
An iterator yielding elements in reversed order.
Note: xs.reverseIterator is the same as xs.reverse.iterator but might be more efficient.
an iterator yielding the elements of this mutable indexed sequence in reversed order
Builds a new collection by applying a function to all elements of this array and collecting the results in reversed order.
Note: xs.reverseMap(f) is the same as xs.reverse.map(f) but might be more efficient.
the element type of the returned collection.
the function to apply to each element.
a new array resulting from applying the given function f to each element of this array and collecting the results in reversed order.
Checks if the other iterable collection contains the same elements in the same order as this array.
the collection to compare with.
true, if both collections contain the same elements in the same order, false otherwise.
Computes a prefix scan of the elements of the collection.
Note: The neutral element z may be applied more than once.
element type of the resulting collection
type of the resulting collection
neutral element for the operator op
the associative operator for the scan
combiner factory which provides a combiner
a new mutable indexed sequence containing the prefix scan of the elements in this mutable indexed sequence
Produces a collection containing cumulative results of applying the operator going left to right.
the type of the elements in the resulting collection
the actual type of the resulting collection
the initial value
the binary operator applied to the intermediate result and the element
an implicit value of class CanBuildFrom which determines the result class That from the current representation type Repr and the new element type B.
collection with intermediate results
Produces a collection containing cumulative results of applying the operator going right to left. The head of the collection is the last cumulative result.
Example:
List(1, 2, 3, 4).scanRight(0)(_ + _) == List(10, 9, 7, 4, 0)
the type of the elements in the resulting collection
the actual type of the resulting collection
the initial value
the binary operator applied to the intermediate result and the element
an implicit value of class CanBuildFrom which determines the result class That from the current representation type Repr and the new element type B.
collection with intermediate results
(Changed in version 2.9.0) The behavior of scanRight has changed. The previous behavior can be reproduced with scanRight.reverse.
Computes length of longest segment whose elements all satisfy some predicate.
the predicate used to test elements.
the index where the search starts.
the length of the longest segment of this mutable indexed sequence starting from index from such that every element of the segment satisfies the predicate p.
A version of this collection with all of the operations implemented sequentially (i.e., in a single-threaded manner).
This method returns a reference to this collection. In parallel collections, it is redefined to return a sequential implementation of this collection. In both cases, it has O(1) complexity.
a sequential view of the collection.
The size of this mutable indexed sequence, equivalent to length.
the number of elements in this mutable indexed sequence.
Selects an interval of elements. The returned collection is made up of all elements x which satisfy the invariant:
from <= indexOf(x) < until
a mutable indexed sequence containing the elements greater than or equal to index from extending up to (but not including) index until of this mutable indexed sequence.
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 mutable indexed sequences 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 mutable indexed sequences 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 Array according to the Ordering which results from transforming an implicitly given Ordering with a transformation function.
the target type of the transformation f, and the type where the ordering ord is defined.
the transformation function mapping elements to some other domain B.
the ordering assumed on domain B.
a mutable indexed sequence consisting of the elements of this mutable indexed 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 mutable indexed sequence according to a comparison function.
The sort is stable. That is, elements that are equal (as determined by lt) appear in the same order in the sorted sequence as in the original.
the comparison function which tests whether its first argument precedes its second argument in the desired ordering.
a mutable indexed sequence consisting of the elements of this mutable indexed sequence sorted according to the comparison function lt.
List("Steve", "Tom", "John", "Bob").sortWith(_.compareTo(_) < 0) =
List("Bob", "John", "Steve", "Tom")
Sorts this mutable indexed sequence according to an Ordering.
The sort is stable. That is, elements that are equal (as determined by lt) appear in the same order in the sorted sequence as in the original.
the ordering to be used to compare elements.
a mutable indexed sequence consisting of the elements of this mutable indexed sequence sorted according to the ordering ord.
Splits this mutable indexed sequence into a prefix/suffix pair according to a predicate.
Note: c span p is equivalent to (but possibly more efficient than) (c takeWhile p, c dropWhile p), provided the evaluation of the predicate p does not cause any side-effects.
a pair consisting of the longest prefix of this mutable indexed sequence whose elements all satisfy p, and the rest of this mutable indexed sequence.
Splits this mutable indexed sequence into two at a given position. Note: c splitAt n is equivalent to (but possibly more efficient than) (c take n, c drop n).
the position at which to split.
a pair of mutable indexed sequences consisting of the first n elements of this mutable indexed sequence, and the other elements.
Tests whether this mutable indexed 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 mutable indexed sequence at index offset, otherwise false.
Tests whether this mutable indexed sequence starts with the given sequence.
the sequence to test
true if this collection has that as a prefix, false otherwise.
Defines the prefix of this object's toString representation.
a string representation which starts the result of toString applied to this mutable indexed sequence. By default the string prefix is the simple name of the collection class mutable indexed sequence.
Sums up the elements of this collection.
the sum of all elements in this array of numbers of type Int. Instead of Int, any other type T with an implicit Numeric[T] implementation can be used as element type of the array and as result type of sum. Examples of such types are: Long, Float, Double, BigInt.
Selects all elements except the first.
a mutable indexed sequence consisting of all elements of this mutable indexed sequence except the first one.
java.lang.UnsupportedOperationException if the mutable indexed sequence is empty.
Iterates over the tails of this mutable indexed sequence. The first value will be this mutable indexed sequence and the final one will be an empty mutable indexed sequence, with the intervening values the results of successive applications of tail.
an iterator over all the tails of this mutable indexed sequence
List(1,2,3).tails = Iterator(List(1,2,3), List(2,3), List(3), Nil)
Selects first n elements.
the number of elements to take from this mutable indexed sequence.
a mutable indexed sequence consisting only of the first n elements of this mutable indexed sequence, or else the whole mutable indexed sequence, if it has less than n elements. If n is negative, returns an empty mutable indexed sequence.
Selects last n elements.
the number of elements to take
a mutable indexed sequence consisting only of the last n elements of this mutable indexed sequence, or else the whole mutable indexed sequence, if it has less than n elements.
Takes longest prefix of elements that satisfy a predicate.
the longest prefix of this mutable indexed sequence whose elements all satisfy the predicate p.
Converts this array into another by copying all elements.
The collection type to build.
a new collection containing all elements of this array.
Converts this array to an array.
an array containing all elements of this array. An ClassTag must be available for the element type of this array.
Uses the contents of this mutable indexed sequence to create a new mutable buffer.
a buffer containing all elements of this mutable indexed sequence.
Converts this mutable indexed sequence to an indexed sequence.
an indexed sequence containing all elements of this mutable indexed sequence.
Returns this mutable indexed sequence as an iterable collection.
A new collection will not be built; lazy collections will stay lazy.
an Iterable containing all elements of this mutable indexed sequence.
Returns an Iterator over the elements in this mutable indexed sequence. Produces the same result as iterator.
an Iterator containing all elements of this mutable indexed sequence.
Converts this mutable indexed sequence to a list.
a list containing all elements of this mutable indexed sequence.
Converts this array to a map. This method is unavailable unless the elements are members of Tuple2, each ((T, U)) becoming a key-value pair in the map. Duplicate keys will be overwritten by later keys: if this is an unordered collection, which key is in the resulting map is undefined.
a map of type immutable.Map[T, U] containing all key/value pairs of type (T, U) of this array.
Converts this mutable indexed sequence to a sequence.
A new collection will not be built; in particular, lazy sequences will stay lazy.
a sequence containing all elements of this mutable indexed sequence.
Converts this mutable indexed sequence to a set.
a set containing all elements of this mutable indexed sequence.
Converts this mutable indexed sequence to a stream.
a stream containing all elements of this mutable indexed sequence.
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.
Converts this mutable indexed sequence to an unspecified Traversable. Will return the same collection if this instance is already Traversable.
a Traversable containing all elements of this mutable indexed sequence.
Converts this mutable indexed sequence to a Vector.
a vector containing all elements of this mutable indexed sequence.
Transposes a two dimensional array.
Type of row elements.
A function that converts elements of this array to rows - arrays of type U.
An array obtained by replacing elements of this arrays with rows the represent.
Produces a new sequence which contains all elements of this array and also all elements of a given sequence. xs union ys is equivalent to xs ++ ys.
Another way to express this is that xs union ys computes the order-preserving multi-set union of xs and ys. union is hence a counter-part of diff and intersect which also work on multi-sets.
the sequence to add.
a new array which contains all elements of this array followed by all elements of that.
Converts an array of pairs into an array of first elements and an array of second elements.
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 Array is a pair.
a class tag for T1 type parameter that is required to create an instance of Array[T1]
a class tag for T2 type parameter that is required to create an instance of Array[T2]
a pair of Arrays, containing, respectively, the first and second half of each element pair of this Array.
Converts an array of triples into three arrays, one containing the elements from each position of the triple.
the type of the first of three elements in the triple
the type of the second of three elements in the triple
the type of the third of three elements in the triple
an implicit conversion which asserts that the element type of this Array is a triple.
a class tag for T1 type parameter that is required to create an instance of Array[T1]
a class tag for T2 type parameter that is required to create an instance of Array[T2]
a class tag for T3 type parameter that is required to create an instance of Array[T3]
a triple of Arrays, containing, respectively, the first, second, and third elements from each element triple of this Array.
Update the element at given index.
Indices start at 0; xs.update(i, x) replaces the ith element in the array. Note the syntax xs(i) = x is a shorthand for xs.update(i, x).
the index
the value to be written at index i
ArrayIndexOutOfBoundsException if i < 0 or length <= i
A copy of this array with one single replaced element.
the position of the replacement
the replacing element
a copy of this array with the element at position index replaced by elem.
A sub-sequence view starting at index from and extending up to (but not including) index until.
The index of the first element of the slice
The index of the element following the slice
a non-strict view of a slice of this mutable indexed sequence, starting at index from and extending up to (but not including) index until.@note The difference between view and slice is that view produces a view of the current sequence, whereas slice produces a new sequence.
view(from, to) is equivalent to view.slice(from, to)
Creates a view of this iterable @see Iterable.View
a non-strict view of this mutable indexed sequence.
Creates a non-strict filter of this mutable indexed sequence.
Note: the difference between c filter p and c withFilter p is that the former creates a new collection, whereas the latter only restricts the domain of subsequent map, flatMap, foreach, and withFilter operations.
the predicate used to test elements.
an object of class WithFilter, which supports map, flatMap, foreach, and withFilter operations. All these operations apply to those elements of this mutable indexed sequence which satisfy the predicate p.
Returns a array formed from this array 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 array containing pairs consisting of corresponding elements of this array and that. The length of the returned collection is the minimum of the lengths of this array and that.
Returns a array formed from this array and another iterable collection by combining corresponding elements in pairs. If one of the two collections is shorter than the other, placeholder elements are used to extend the shorter collection to the length of the longer.
the type of the second half of the returned pairs
The iterable providing the second half of each result pair
the element to be used to fill up the result if this array is shorter than that.
the element to be used to fill up the result if that is shorter than this array.
a new array containing pairs consisting of corresponding elements of this array and that. The length of the returned collection is the maximum of the lengths of this array and that. If this array is shorter than that, thisElem values are used to pad the result. If that is shorter than this array, thatElem values are used to pad the result.
Zips this array with its indices.
A new array containing pairs consisting of all elements of this array paired with their index. Indices start at 0.
List("a", "b", "c").zipWithIndex = List(("a", 0), ("b", 1), ("c", 2))
Selects an element by its index in the mutable indexed sequence.
Example:
scala> val x = List(1, 2, 3, 4, 5) x: List[Int] = List(1, 2, 3, 4, 5) scala> x(3) res1: Int = 4
The index to select.
the element of this mutable indexed sequence at index idx, where 0 indicates the first element.
(array: ArrayOps[T]).apply(idx)
IndexOutOfBoundsException if idx does not satisfy 0 <= idx < length.
The equals method for arbitrary sequences. Compares this sequence to some other object.
The object to compare the sequence to
true if that is a sequence that has the same elements as this sequence in the same order, false otherwise
(array: ArrayOps[T]).equals(that)
Hashcodes for Array produce a value from the hashcodes of all the elements of the mutable indexed sequence.
the hash code value for this object.
(array: ArrayOps[T]).hashCode()
The length of the mutable indexed sequence.
Note: xs.length and xs.size yield the same result.
the number of elements in this mutable indexed sequence.
(array: ArrayOps[T]).length
IllegalArgumentException if the length of the sequence cannot be represented in an Int, for example, (-1 to Int.MaxValue).length.
(array: ArrayCharSequence).length()
Converts this mutable indexed sequence to a string.
a string representation of this collection. By default this string consists of the stringPrefix of this mutable indexed sequence, followed by all elements separated by commas and enclosed in parentheses.
(array: ArrayOps[T]).toString()
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.
(array: ArrayCharSequence).toString()
Replaces element at given index with a new value.
the index of the element to replace.
the new value.
(array: ArrayOps[T]).update(idx, elem)
IndexOutOfBoundsException if the index is not valid.
© 2002-2019 EPFL, with contributions from Lightbend.
Licensed under the Apache License, Version 2.0.
https://www.scala-lang.org/api/2.12.9/scala/Array.html
Arrays are mutable, indexed collections of values.
Array[T]is Scala's representation for Java'sT[].Arrays make use of two common pieces of Scala syntactic sugar, shown on lines 2 and 3 of the above example code. Line 2 is translated into a call to
apply(Int), while line 3 is translated into a call toupdate(Int, T).Two implicit conversions exist in scala.Predef that are frequently applied to arrays: a conversion to scala.collection.mutable.ArrayOps (shown on line 4 of the example above) and a conversion to scala.collection.mutable.WrappedArray (a subtype of scala.collection.Seq). Both types make available many of the standard operations found in the Scala collections API. The conversion to
ArrayOpsis temporary, as all operations defined onArrayOpsreturn anArray, while the conversion toWrappedArrayis permanent as all operations return aWrappedArray.The conversion to
ArrayOpstakes priority over the conversion toWrappedArray. For instance, consider the following code:Value
arrReversedwill be of typeArray[Int], with an implicit conversion toArrayOpsoccurring to perform thereverseoperation. The value ofseqReversed, on the other hand, will be computed by converting toWrappedArrayfirst and invoking the variant ofreversethat returns anotherWrappedArray.1.0
Scala Language Specification, for in-depth information on the transformations the Scala compiler makes on Arrays (Sections 6.6 and 6.15 respectively.)
"Scala 2.8 Arrays" the Scala Improvement Document detailing arrays since Scala 2.8.
"The Scala 2.8 Collections' API" section on
Arrayby Martin Odersky for more information.