nullperm: Null permutations

Description Usage Format Details Note See Also Examples

Description

Null permutations are the equivalent of NULL

Usage

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Format

Object nullcycle is an empty list coerced to class cycle, specfically 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.

Note

The objects documented here are distinct from the identity permutation, id, documented separately.

See Also

id

Examples

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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.

permutations documentation built on Nov. 13, 2020, 1:14 a.m.