A flexible iterator for transforming an Iterator[A] into an Iterator[Seq[A]], with configurable sequence size, step, and strategy for dealing with remainder elements which don't fit evenly into the last group.
A flexible iterator for transforming an Iterator[A] into an Iterator[Seq[A]], with configurable sequence size, step, and strategy for dealing with remainder elements which don't fit evenly into the last group.
A GroupedIterator is yielded by grouped and by sliding, where the step may differ from the group size.
Check if there is a next element available.
Check if there is a next element available.
Attributestrue if there is a next element, false otherwise
Reuse: The iterator remains valid for further use whatever result is returned.
Return the next element and advance the iterator.
Return the next element and advance the iterator.
Attributesthe next element.
Reuse: Advances the iterator, which may exhaust the elements. It is valid to make additional calls on the iterator.
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.
Creates a buffered iterator from this iterator.
Creates a buffered iterator from this iterator.
Attributesa buffered iterator producing the same values as this iterator.
Reuse: After calling this method, one should discard the iterator it was called on, and use only the iterator that was returned. Using the old iterator is undefined, subject to change, and may result in changes to the new iterator as well.
Builds a new iterator by applying a partial function to all elements of this iterator on which the function is defined.
Builds a new iterator by applying a partial function to all elements of this iterator on which the function is defined.
Type parametersthe element type of the returned iterator.
the partial function which filters and maps the iterator.
a new iterator 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)
Tests whether this iterator contains a given value as an element.
Tests whether this iterator contains a given value as an element.
Note: may not terminate for infinite iterators.
Value parametersthe element to test.
true if this iterator produces some value that is is equal (as determined by ==) to elem, false otherwise.
Reuse: After calling this method, one should discard the iterator it was called on. Using it is undefined and subject to change.
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
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.
Builds a new iterator from this one without any duplicated elements on it.
Builds a new iterator from this one without any duplicated elements on it.
Attributesiterator with distinct elements
Reuse: After calling this method, one should discard the iterator it was called on. Using it is undefined and subject to change.
Builds a new iterator from this one without any duplicated elements as determined by == after applying the transforming function f.
Builds a new iterator from this one without any duplicated elements 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
iterator with distinct elements
Reuse: After calling this method, one should discard the iterator it was called on. Using it is undefined and subject to change.
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 iterator.
a iterator consisting of all elements of this iterator except the first n ones, or else the empty iterator, if this iterator has less than n elements. If n is negative, don't drop any elements.
Selects 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 iterator, 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 iterator.
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 iterator whose first element does not satisfy the predicate p.
Creates two new iterators that both iterate over the same elements as this iterator (in the same order).
Creates two new iterators that both iterate over the same elements as this iterator (in the same order). The duplicate iterators are considered equal if they are positioned at the same element.
Given that most methods on iterators will make the original iterator unfit for further use, this methods provides a reliable way of calling multiple such methods on an iterator.
Attributesa pair of iterators
The implementation may allocate temporary storage for elements iterated by one iterator but not yet by the other.
Reuse: After calling this method, one should discard the iterator it was called on, and use only the iterators that were returned. Using the old iterator is undefined, subject to change, and may result in changes to the new iterators as well.
Tests whether 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 iterator which satisfy a predicate.
Selects all elements of this iterator which satisfy a predicate.
Value parametersthe predicate used to test elements.
a new iterator consisting of all elements of this iterator that satisfy the given predicate p. The order of the elements is preserved.
Selects all elements of this iterator which do not satisfy a predicate.
Selects all elements of this iterator which do not satisfy a predicate.
Value parametersthe predicate used to test elements.
a new iterator consisting of all elements of this iterator 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.
Builds a new iterator by applying a function to all elements of this iterator and using the elements of the resulting collections.
Builds a new iterator by applying a function to all elements of this iterator 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 iterator. 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 iterator resulting from applying the given collection-valued function f to each element of this iterator and concatenating the results.
Converts this iterator of iterable collections into a iterator formed by the elements of these iterable collections.
Converts this iterator of iterable collections into a iterator formed by the elements of these iterable collections.
The resulting collection's type will be guided by the type of iterator. 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 iterator is an Iterable.
a new iterator resulting from concatenating all element iterators.
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.
Returns an iterator which groups this iterator into fixed size blocks.
Returns an iterator which groups this iterator into fixed size blocks. Example usages:
// Returns List(List(1, 2, 3), List(4, 5, 6), List(7)))
(1 to 7).iterator.grouped(3).toList
// Returns List(List(1, 2, 3), List(4, 5, 6))
(1 to 7).iterator.grouped(3).withPartial(false).toList
// Returns List(List(1, 2, 3), List(4, 5, 6), List(7, 20, 25)
// Illustrating that withPadding's argument is by-name.
val it2 = Iterator.iterate(20)(_ + 5)
(1 to 7).iterator.grouped(3).withPadding(it2.next).toList
Reuse: After calling this method, one should discard the iterator it was called on, and use only the iterator that was returned. Using the old iterator is undefined, subject to change, and may result in changes to the new iterator as well.
Returns the index of the first occurrence of the specified object in this iterable object after or at some start index.
Returns the index of the first occurrence of the specified object in this iterable object after or at some start index.
Note: may not terminate for infinite iterators.
Value parameterselement to search for.
the start index
the index >= from of the first occurrence of elem in the values produced by this iterator, or -1 if such an element does not exist until the end of the iterator is reached.
Reuse: After calling this method, one should discard the iterator it was called on. Using it is undefined and subject to change.
Returns the index of the first occurrence of the specified object in this iterable object.
Returns the index of the first occurrence of the specified object in this iterable object.
Note: may not terminate for infinite iterators.
Value parameterselement to search for.
the index of the first occurrence of elem in the values produced by this iterator, or -1 if such an element does not exist until the end of the iterator is reached.
Reuse: After calling this method, one should discard the iterator it was called on. Using it is undefined and subject to change.
Tests whether the iterator is empty.
Tests whether the iterator 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 iterator contains no elements, false otherwise.
Tests whether this collection can be repeatedly traversed.
Tests whether this 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.
AttributesBuilds a new iterator by applying a function to all elements of this iterator.
Builds a new iterator by applying a function to all elements of this iterator.
Type parametersthe element type of the returned iterator.
the function to apply to each element.
a new iterator resulting from applying the given function f to each element of this iterator 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)"
Wraps the value of next() in an option.
Wraps the value of next() in an option.
Some(next) if a next element exists, None otherwise.
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 iterator with an element value appended until a given target length is reached.
A copy of this iterator with an element value appended until a given target length is reached.
Type parametersthe element type of the returned iterator.
the padding value
the target length
a new iterator consisting of all elements of this iterator followed by the minimal number of occurrences of elem so that the resulting collection has a length of at least len.
Partitions this iterator in two iterators according to a predicate.
Partitions this iterator in two iterators according to a predicate.
Value parametersthe predicate on which to partition
a pair of iterators: the iterator that satisfies the predicate p and the iterator that does not. The relative order of the elements in the resulting iterators is the same as in the original iterator.
Reuse: After calling this method, one should discard the iterator it was called on, and use only the iterators that were returned. Using the old iterator is undefined, subject to change, and may result in changes to the new iterators as well.
Returns this iterator with patched values.
Returns this iterator with patched values. Patching at negative indices is the same as patching starting at 0. Patching at indices at or larger than the length of the original iterator appends the patch to the end. If more values are replaced than actually exist, the excess is ignored.
Value parametersThe start index from which to patch
The iterator of patch values
The number of values in the original iterator that are replaced by the patch.
Reuse: After calling this method, one should discard the iterator it was called on, as well as the one passed as a parameter, and use only the iterator that was returned. Using the old iterators is undefined, subject to change, and may result in changes to the new iterator as well.
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.
Checks whether corresponding elements of the given iterable collection compare equal (with respect to ==) to elements of this iterator.
Checks whether corresponding elements of the given iterable collection compare equal (with respect to ==) to elements of this iterator.
the type of the elements of collection that.
the collection to compare
true if both collections contain equal elements in the same order, false otherwise. <invalid inheritdoc annotation>
Produces a iterator containing cumulative results of applying the operator going left to right, including the initial value.
Produces a iterator 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
The size of this collection.
The size of this collection.
Note: will not terminate for infinite-sized collections.
Attributesthe number of elements in this collection.
Selects an interval of elements.
Selects an interval of elements. The returned iterator 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 iterator.
the lowest index to EXCLUDE from this iterator.
a iterator containing the elements greater than or equal to index from extending up to (but not including) index until of this iterator.
Returns an iterator which presents a "sliding window" view of this iterator.
Returns an iterator which presents a "sliding window" view of this iterator. The first argument is the window size, and the second argument step is how far to advance the window on each iteration. The step defaults to 1.
The returned GroupedIterator can be configured to either pad a partial result to size size or suppress the partial result entirely.
Example usages:
// Returns List(ArraySeq(1, 2, 3), ArraySeq(2, 3, 4), ArraySeq(3, 4, 5))
(1 to 5).iterator.sliding(3).toList
// Returns List(ArraySeq(1, 2, 3, 4), ArraySeq(4, 5))
(1 to 5).iterator.sliding(4, 3).toList
// Returns List(ArraySeq(1, 2, 3, 4))
(1 to 5).iterator.sliding(4, 3).withPartial(false).toList
// Returns List(ArraySeq(1, 2, 3, 4), ArraySeq(4, 5, 20, 25))
// Illustrating that withPadding's argument is by-name.
val it2 = Iterator.iterate(20)(_ + 5)
(1 to 5).iterator.sliding(4, 3).withPadding(it2.next).toList
the number of elements per group
the distance between the first elements of successive groups
A GroupedIterator producing Seq[B]s 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. This behavior can be configured.
Reuse: After calling this method, one should discard the iterator it was called on, and use only the iterator that was returned. Using the old iterator is undefined, subject to change, and may result in changes to the new iterator as well.
Splits this iterator into a prefix/suffix pair according to a predicate.
Splits this iterator 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.
AttributesReuse: After calling this method, one should discard the iterator it was called on, and use only the iterators that were returned. Using the old iterator is undefined, subject to change, and may result in changes to the new iterators as well.
Splits this collection into a prefix/suffix pair at a given position.
Splits this 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 collections consisting of the first n elements of this collection, and the other elements.
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.
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 iterator.
a iterator consisting only of the first n elements of this iterator, or else the whole iterator, if it has less than n elements. If n is negative, returns an empty iterator.
Selects the longest prefix of elements that satisfy a predicate.
Selects the longest prefix of elements that satisfy a predicate.
The matching prefix starts with the first element of this iterator, and the element following the prefix is the first element that does not satisfy the predicate. The matching prefix may empty, so that this method returns an empty iterator.
Example:
scala> List(1, 2, 3, 100, 4).takeWhile(n => n < 10)
val res0: List[Int] = List(1, 2, 3)
scala> List(1, 2, 3, 100, 4).takeWhile(n => n == 0)
val res1: List[Int] = List()
Use span to obtain both the prefix and suffix. Use filter to retain only those elements from the entire iterator 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 prefix of this iterator 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 iterator
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 iterator to a string.
Converts this iterator to a string.
Attributes"<iterator>"
Reuse: The iterator remains valid for further use whatever result is returned.
Converts this collection to a Vector.
Creates an iterator over all the elements of this iterator that satisfy the predicate p.
Creates an iterator over all the elements of this iterator that satisfy the predicate p. The order of the elements is preserved.
Note: withFilter is the same as filter on iterators. It exists so that for-expressions with filters work over iterators.
the predicate used to test values.
an iterator which produces those values of this iterator which satisfy the predicate p.
Reuse: After calling this method, one should discard the iterator it was called on, and use only the iterator that was returned. Using the old iterator is undefined, subject to change, and may result in changes to the new iterator as well.
Zips this iterator with its indices.
Zips this iterator with its indices.
AttributesA new iterator containing pairs consisting of all elements of this iterator paired with their index. Indices start at 0.
List("a", "b", "c").zipWithIndex == List(("a", 0), ("b", 1), ("c", 2))
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 iterator is known to have a finite size.
Tests whether this iterator is known to have a finite size. All strict collections are known to have finite size. For a non-strict collection such as Stream, the predicate 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] hasDefiniteSize on Iterator is the same as isEmpty
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.
[Since version 2.13.0] Call scanRight on an Iterable instead.
[Since version 2.13.0] Iterator.seq always returns the iterator itself
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