The identity permutation
The identity permutation leaves every element fixed
is.id(x) is.id_single_cycle(x) ## S3 method for class 'cycle' is.id(x) ## S3 method for class 'list' is.id(x) ## S3 method for class 'word' is.id(x)
x |
Object to be tested |
The identity permutation is problematic because it potentially has zero size.
The variable id is a cycle as this is more convenient
than a zero-by-one matrix.
Function is.id() returns a Boolean with TRUE if the
corresponding element is the identity, and FALSE otherwise. It
dispatches to either is.id.cycle() or is.id.word() as
appropriate.
Function is.id.list() tests a cyclist for identityness.
The identity permutations documented here are distinct from the null
permutations documented at nullperm.Rd.
Robin K. S. Hankin
is.id(id) as.word(id) # weird x <- rperm(10,4) x[3] <- id is.id(x*inverse(x))
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