permutations (version 1.1-5)

nullperm: Null permutations

Description

Null permutations are the equivalent of NULL

Usage

nullcycle
nullword

Format

Object nullcycle is an empty list coerced to class cycle, specifically cycle(list())

Object nullword is a zero-row matrix, coerced to word, specifically word(matrix(integer(0),0,0))

Details

These objects are here to deal with the case where a length-zero permutation is extracted. The behaviour of these null objects is not entirely consistent.

See Also

id

Examples

rperm(10,4)[0]  # null word

as.cycle(1:5)[0]  # null cycle

data(megaminx)
c(NULL,megaminx)      # probably not what the user intended...
c(nullcycle,megaminx) # more useful.
c(id,megaminx)        # also useful.