A flexible iterator for transforming an Iterator[A] into an Iterator[Seq[A]], with configurable sequence size, step, and strategy for dealing with elements which don't fit evenly.
Typical uses can be achieved via methods grouped and sliding.
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 ==
The expression x == that is equivalent to if (x eq null) that eq null else x.equals(that).
true if the receiver object is equivalent to the argument; false otherwise.
Appends all elements of this collection to a string builder. The written text consists of the string representations (w.r.t. the method toString) of all elements of this collection without any separator string.
Example:
scala> val a = List(1,2,3,4) a: List[Int] = List(1, 2, 3, 4) scala> val b = new StringBuilder() b: StringBuilder = scala> val h = a.addString(b) h: StringBuilder = 1234
the string builder to which elements are appended.
the string builder b to which elements were appended.
Appends all elements of this collection to a string builder using a separator string. The written text consists of the string representations (w.r.t. the method toString) of all elements of this collection, separated by the string sep.
Example:
scala> val a = List(1,2,3,4) a: List[Int] = List(1, 2, 3, 4) scala> val b = new StringBuilder() b: StringBuilder = scala> a.addString(b, ", ") res0: StringBuilder = 1, 2, 3, 4
the string builder to which elements are appended.
the separator string.
the string builder b to which elements were appended.
Appends all elements of this collection to a string builder using start, end, and separator strings. The written text begins with the string start and ends with the string end. Inside, the string representations (w.r.t. the method toString) of all elements of this collection are separated by the string sep.
Example:
scala> val a = List(1,2,3,4)
a: List[Int] = List(1, 2, 3, 4)
scala> val b = new StringBuilder()
b: StringBuilder =
scala> a.addString(b , "List(" , ", " , ")")
res5: StringBuilder = List(1, 2, 3, 4)
the string builder to which elements are appended.
the starting string.
the separator string.
the ending string.
the string builder b to which elements were appended.
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.
Creates a buffered iterator from this iterator.
a 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.
Create a copy of the receiver object.
The default implementation of the clone method is platform dependent.
a copy of the receiver object.
Builds a new iterator by applying a partial function to all elements of this iterator on which the function is defined.
the 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.
Reuse: After calling this method, one should discard the iterator it was called on, and use only the iterator that was returned. Using the old iterator is undefined, subject to change, and may result in changes to the new iterator as well.
Finds the first element of the collection for which the given partial function is defined, and applies the partial function to it.
Note: may not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered.
the partial function
an option value containing pf applied to the first value for which it is defined, or None if none exists.
Seq("a", 1, 5L).collectFirst({ case x: Int => x*10 }) = Some(10)
Tests whether this iterator contains a given value as an element.
Note: may not terminate for infinite iterators.
the 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.
Fills the given array xs starting at index start with at most len elements of this collection.
Copying will stop once either all the elements of this collection have been copied, or the end of the array is reached, or len elements have been copied.
the type of the elements of the array.
the array to fill.
the starting index of xs.
the maximal number of elements to copy.
the number of elements written to the array
Reuse: After calling this method, one should discard the iterator it was called on. Using it is undefined and subject to change. Note: will not terminate for infinite-sized collections.
Copy elements to an array, returning the number of elements written.
Fills the given array xs starting at index start with values of this collection.
Copying will stop once either all the elements of this collection have been copied, or the end of the array is reached.
the type of the elements of the array.
the array to fill.
the starting index of xs.
the number of elements written to the array Note: will not terminate for infinite-sized collections.
Copy elements to an array, returning the number of elements written.
Fills the given array xs starting at index start with values of this collection.
Copying will stop once either all the elements of this collection have been copied, or the end of the array is reached.
the type of the elements of the array.
the array to fill.
the number of elements written to the array Note: will not terminate for infinite-sized collections.
Tests whether every element of this collection's iterator relates to the corresponding element of another collection by satisfying a test predicate.
the type of the elements of that
the other collection
the test predicate, which relates elements from both collections
true if both collections have the same length and p(x, y) is true for all corresponding elements x of this iterator and y of that, otherwise false
Counts the number of elements in the collection which satisfy a predicate.
the predicate used to test elements.
the number of elements satisfying the predicate p.
Builds a new iterator from this one without any duplicated elements on it.
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.
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 first n ones.
Note: might return different results for different runs, unless the underlying collection type is ordered.
the 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.
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.
Drops longest prefix of elements that satisfy a predicate.
Note: might return different results for different runs, unless the underlying collection type is ordered.
The predicate used to test elements.
the longest suffix of this iterator whose first element does not satisfy the predicate p.
Reuse: After calling this method, one should discard the iterator it was called on, and use only the iterator that was returned. Using the old iterator is undefined, subject to change, and may result in changes to the new iterator as well.
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.
a 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 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 collection.
Note: may not terminate for infinite-sized collections.
the predicate used to test elements.
true if the given predicate p is satisfied by at least one element of this collection, otherwise false
Selects all elements of this iterator which satisfy a predicate.
the 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.
a new iterator consisting of all elements of this iterator that do not satisfy the given predicate pred. Their order may not be preserved.
Called by the garbage collector on the receiver object when there are no more references to the object.
The details of when and if the finalize method is invoked, as well as the interaction between finalize and non-local returns and exceptions, are all platform dependent.
Finds the first element of the collection satisfying a predicate, if any.
Note: may not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered.
the predicate used to test elements.
an option value containing the first element in the collection that satisfies p, or None if none exists.
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.
Reuse: After calling this method, one should discard the iterator it was called on, and use only the iterator that was returned. Using the old iterator is undefined, subject to change, and may result in changes to the new iterator as well.
Converts this iterator of traversable collections into a iterator formed by the elements of these traversable 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 traversable collection.
a new iterator resulting from concatenating all element iterators.
Reuse: After calling this method, one should discard the iterator it was called on, and use only the iterator that was returned. Using the old iterator is undefined, subject to change, and may result in changes to the new iterator as well.
Folds the elements of this collection using the specified associative binary operator. The default implementation in IterableOnce is equivalent to foldLeft but may be overridden for more efficient traversal orders.
The order in which operations are performed on elements is unspecified and may be nondeterministic.
Note: will not terminate for infinite-sized collections.
a type parameter for the binary operator, a supertype of A.
a neutral element for the fold operation; may be added to the result an arbitrary number of times, and must not change the result (e.g., Nil for list concatenation, 0 for addition, or 1 for multiplication).
a binary operator that must be associative.
the result of applying the fold operator op between all the elements and z, or z if this collection is empty.
Applies a binary operator to a start value and all elements of this collection, going left to right.
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.
the result type of the binary operator.
the start value.
the binary operator.
the result of inserting op between consecutive elements of this collection, going left to right with the start value z on the left:
op(...op(z, x_1), x_2, ..., x_n)
where x1, ..., xn are the elements of this collection. Returns z if this collection is empty.
Applies a binary operator to all elements of this collection and a start value, going right to left.
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.
the result type of the binary operator.
the start value.
the binary operator.
the result of inserting op between consecutive elements of this collection, going right to left with the start value z on the right:
op(x_1, op(x_2, ... op(x_n, z)...))
where x1, ..., xn are the elements of this collection. Returns z if this collection is empty.
Tests whether a predicate holds for all elements of this collection.
Note: may not terminate for infinite-sized collections.
the predicate used to test elements.
true if this collection is empty or the given predicate p holds for all elements of this collection, otherwise false.
Apply f to each element for its side effects Note: [U] parameter needed to help scalac's type inference.
Returns string formatted according to given format string. Format strings are as for String.format (@see java.lang.String.format).
Returns the runtime class representation of the object.
a class object corresponding to the runtime type of the receiver.
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.
Check if there is a next element available.
true if there is a next element, false otherwise
Reuse: The iterator remains valid for further use whatever result is returned.
The hashCode method for reference types. See hashCode in scala.Any.
the hash code value for this object.
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.
element 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.
Note: may not terminate for infinite iterators.
element 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.
Note: Implementations in subclasses that are not repeatedly traversable must take care not to consume any elements when isEmpty is called.
true if the iterator contains no elements, false otherwise.
Test whether the dynamic type of the receiver object is T0.
Note that the result of the test is modulo Scala's erasure semantics. Therefore the expression 1.isInstanceOf[String] will return false, while the expression List(1).isInstanceOf[List[String]] will return true. In the latter example, because the type argument is erased as part of compilation it is not possible to check whether the contents of the list are of the specified type.
true if the receiver object is an instance of erasure of type T0; false otherwise.
Tests whether this collection can be repeatedly traversed. Always true for Iterables and false for Iterators unless overridden.
true if it is repeatedly traversable, false otherwise.
Iterator can be used only once
The number of elements in this collection, if it can be cheaply computed, -1 otherwise. Cheaply usually means: Not requiring a collection traversal.
Builds a new iterator by applying a function to all elements of this iterator.
the 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.
Reuse: After calling this method, one should discard the iterator it was called on, and use only the iterator that was returned. Using the old iterator is undefined, subject to change, and may result in changes to the new iterator as well.
Finds the largest element.
The 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.
UnsupportedOperationException if this collection is empty.
Finds the first element which yields the largest value measured by function f.
The result type of the function f.
The measuring function.
An ordering to be used for comparing elements.
the first element of this collection with the largest value measured by function f with respect to the ordering cmp.
UnsupportedOperationException if this collection is empty.
Finds the first element which yields the largest value measured by function f.
The result type of the function f.
The measuring function.
An ordering to be used for comparing elements.
an option value containing the first element of this collection with the largest value measured by function f with respect to the ordering cmp.
Finds the largest element.
The type over which the ordering is defined.
An ordering to be used for comparing elements.
an option value containing the largest element of this collection with respect to the ordering ord.
Finds the smallest element.
The 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.
UnsupportedOperationException if this collection is empty.
Finds the first element which yields the smallest value measured by function f.
The result type of the function f.
The measuring function.
An ordering to be used for comparing elements.
the first element of this collection with the smallest value measured by function f with respect to the ordering cmp.
UnsupportedOperationException if this collection is empty.
Finds the first element which yields the smallest value measured by function f.
The result type of the function f.
The measuring function.
An ordering to be used for comparing elements.
an option value containing the first element of this collection with the smallest value measured by function f with respect to the ordering cmp.
Finds the smallest element.
The type over which the ordering is defined.
An ordering to be used for comparing elements.
an option value containing the smallest element of this collection with respect to the ordering ord.
Displays all elements of this collection in a string.
Delegates to addString, which can be overridden.
a string representation of this collection. In the resulting string the string representations (w.r.t. the method toString) of all elements of this collection follow each other without any separator string.
Displays all elements of this collection in a string using a separator string.
Delegates to addString, which can be overridden.
the separator string.
a string representation of this collection. In the resulting string the string representations (w.r.t. the method toString) of all elements of this collection are separated by the string sep.
List(1, 2, 3).mkString("|") = "1|2|3"
Displays all elements of this collection in a string using start, end, and separator strings.
Delegates to addString, which can be overridden.
the starting string.
the separator string.
the ending string.
a string representation of this collection. The resulting string begins with the string start and ends with the string end. Inside, the string representations (w.r.t. the method toString) of all elements of this collection are separated by the string sep.
List(1, 2, 3).mkString("(", "; ", ")") = "(1; 2; 3)"
Equivalent to !(this eq that).
true if the argument is not a reference to the receiver object; false otherwise.
Return the next element and advance the iterator.
the next element.
NoSuchElementException if there is no next element.
Reuse: Advances the iterator, which may exhaust the elements. It is valid to make additional calls on the iterator.
Wraps the value of next() in an option.
Some(next) if a next element exists, None otherwise.
Tests whether the collection is not empty.
true if the collection contains at least one element, false otherwise.
Wakes up a single thread that is waiting on the receiver object's monitor.
not specified by SLS as a member of AnyRef
Wakes up all threads that are waiting on the receiver object's monitor.
not specified by SLS as a member of AnyRef
A copy of this iterator with an element value appended until a given target length is reached.
the element type of the returned iterator.
the target length
the padding value
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.
the 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. 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.
The 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 up the elements of this collection.
the result type of the * operator.
an implicit parameter defining a set of numeric operations which includes the * operator to be used in forming the product.
the product of all elements of this collection with respect to the * operator in num.
Reduces the elements of this collection using the specified associative binary operator.
The order in which operations are performed on elements is unspecified and may be nondeterministic.
A type parameter for the binary operator, a supertype of A.
A binary operator that must be associative.
The result of applying reduce operator op between all the elements if the collection is nonempty.
UnsupportedOperationException if this collection is empty.
Applies a binary operator to all elements of this collection, going left to right.
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.
the result type of the binary operator.
the binary operator.
the result of inserting op between consecutive elements of this collection, going left to right:
op( op( ... op(x_1, x_2) ..., x_{n-1}), x_n)
where x1, ..., xn are the elements of this collection.
UnsupportedOperationException if this collection is empty.
Optionally applies a binary operator to all elements of this collection, going left to right.
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.
the result type of the binary operator.
the binary operator.
an option value containing the result of reduceLeft(op) if this collection is nonempty, None otherwise.
Reduces the elements of this collection, if any, using the specified associative binary operator.
The order in which operations are performed on elements is unspecified and may be nondeterministic.
A type parameter for the binary operator, a supertype of A.
A binary operator that must be associative.
An option value containing result of applying reduce operator op between all the elements if the collection is nonempty, and None otherwise.
Applies a binary operator to all elements of this collection, going right to left.
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.
the result type of the binary operator.
the binary operator.
the result of inserting op between consecutive elements of this collection, going right to left:
op(x_1, op(x_2, ..., op(x_{n-1}, x_n)...))
where x1, ..., xn are the elements of this collection.
UnsupportedOperationException if this collection is empty.
Optionally applies a binary operator to all elements of this collection, going right to left.
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.
the result type of the binary operator.
the binary operator.
an option value containing the result of reduceRight(op) if this collection is nonempty, None otherwise.
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.
the type of the elements in the resulting collection
the initial value
the binary operator applied to the intermediate result and the element
collection with intermediate results
Reuse: After calling this method, one should discard the iterator it was called on, and use only the iterator that was returned. Using the old iterator is undefined, subject to change, and may result in changes to the new iterator as well.
The size of this collection.
Note: will not terminate for infinite-sized collections.
the number of elements in this collection.
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.
the 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.
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.
Creates an optionally bounded slice, unbounded if until is negative.
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 default GroupedIterator can be configured to either pad a partial result to size size or suppress the partial result entirely.
Example usages:
// Returns List(List(1, 2, 3), List(2, 3, 4), List(3, 4, 5)) (1 to 5).iterator.sliding(3).toList // Returns List(List(1, 2, 3, 4), List(4, 5)) (1 to 5).iterator.sliding(4, 3).toList // Returns List(List(1, 2, 3, 4)) (1 to 5).iterator.sliding(4, 3).withPartial(false).toList // Returns List(List(1, 2, 3, 4), List(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
An iterator 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.
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.
the test predicate
a pair consisting of the longest prefix of this iterator whose elements all satisfy p, and the rest of this 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.
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.
the position at which to split.
a pair of collections consisting of the first n elements of this collection, and the other elements.
Reuse: After calling this method, one should discard the iterator it was called on, and use only the iterators that were returned. Using the old iterator is undefined, subject to change, and may result in changes to the new iterators as well.
Returns a Stepper for the elements of this collection.
The Stepper enables creating a Java stream to operate on the collection, see scala.jdk.StreamConverters. For collections holding primitive values, the Stepper can be used as an iterator which doesn't box the elements.
The implicit StepperShape parameter defines the resulting Stepper type according to the element type of this collection.
Int, Short, Byte or Char, an IntStepper is returnedFor collections of Double or Float, a DoubleStepper is returnedFor collections of Long a LongStepper is returnedFor any other element type, an AnyStepper is returnedNote that this method is overridden in subclasses and the return type is refined to S with EfficientSplit, for example IndexedSeqOps.stepper. For Steppers marked with scala.collection.Stepper.EfficientSplit, the converters in scala.jdk.StreamConverters allow creating parallel streams, whereas bare Steppers can be converted only to sequential streams.
Sums up the elements of this collection.
the result type of the + operator.
an implicit parameter defining a set of numeric operations which includes the + operator to be used in forming the sum.
the sum of all elements of this collection with respect to the + operator in num.
Selects the first n elements.
Note: might return different results for different runs, unless the underlying collection type is ordered.
the 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.
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.
Takes longest prefix of elements that satisfy a predicate.
Note: might return different results for different runs, unless the underlying collection type is ordered.
The predicate used to test elements.
the longest prefix of this iterator whose elements all 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.
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, convert this collection to the appropriate representation for the current element type A. Example uses:
xs.to(List) xs.to(ArrayBuffer) xs.to(BitSet) // for xs: Iterable[Int]
Convert collection to array.
This collection as a Seq[A]. This is equivalent to to(Seq) but might be faster.
Converts this iterator to a string.
"<iterator>"
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.
A 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))
Reuse: After calling this method, one should discard the iterator it was called on, and use only the iterator that was returned. Using the old iterator is undefined, subject to change, and may result in changes to the new iterator as well.
© 2002-2019 EPFL, with contributions from Lightbend.
Licensed under the Apache License, Version 2.0.
https://www.scala-lang.org/api/2.13.0/scala/io/Source$LineIterator.html