ipermutations: Iterator that generates all permutations of an iterable...
In ramhiser/itertools2: Iterators for efficient looping

Description Usage Arguments Details Value Examples

Constructs an iterator generates all permutations of an iterable object. By default, full-length permutations are generated. If m is specified, successive m length permutations are instead generated.

1	ipermutations(object, m = NULL)

`object`	vector
`m`	length of permutations. By default, full-length permutations are generated.

The implementation is loosely based on that of Python's itertools.

iterator that generates all permutations of object

it <- ipermutations(1:3)

iterators::nextElem(it) # c(1, 2, 3)
iterators::nextElem(it) # c(1, 3, 2)
iterators::nextElem(it) # c(3, 1, 2)
iterators::nextElem(it) # c(3, 2, 1)
iterators::nextElem(it) # c(2, 3, 1)
iterators::nextElem(it) # c(2, 1, 3)

it2 <- ipermutations(letters[1:4])
# 24 = 4! permutations of the letters a, b, c, and d
as.list(it2)