| islice {itertools2} | R Documentation |
Iterator that returns selected elements from an iterable.
Description
Constructs an iterator that returns elements from an iterable following the
given sequence with starting value start and ending value end.
The sequence's step size is given by step.
Usage
islice(object, start = 1, end = NULL, step = 1)
Arguments
object |
iterable object through which this function iterates |
start |
the index of the first element to return from |
end |
the index of the last element to return from |
step |
the step size of the sequence |
Details
The iterable given in object is traversed beginning with element
having index specified in start. If start is greater than 1,
then elements from the object are skipped until start is
reached. By default, elements are returned consecutively. However, if the
step size is greater than 1, elements in object are skipped.
If stop is NULL (default), the iteration continues until the
iterator is exhausted unless end is specified. In this case,
end specifies the sequence position to stop iteration.
Value
iterator that returns object in sequence
Examples
it <- islice(1:5, start=2)
iterators::nextElem(it) # 2
iterators::nextElem(it) # 3
iterators::nextElem(it) # 4
iterators::nextElem(it) # 5
it2 <- islice(1:10, start=2, end=5)
unlist(as.list(it2)) == 2:5
it3 <- islice(1:10, start=2, end=9, step=2)
unlist(as.list(it3)) == c(2, 4, 6, 8)