permutations (version 1.1-2)

as.function.permutation: Coerce a permutation to a function

Description

Coerce a permutation to an executable function

Usage

# S3 method for permutation
as.function(x, ...)

Arguments

x

permutation

...

further arguments (currently ignored)

Author

Robin K. S. Hankin

Examples

x <- cyc_len(3)
y <- cyc_len(5)

xfun <- as.function(x)
yfun <- as.function(y)

stopifnot(xfun(yfun(2)) == as.function(y*x)(2)) # note transposition of x & y

# written in postfix notation one has the very appealing form x(fg) = (xf)g

# it's vectorized:
as.function(rperm(10,9))(1)   
as.function(as.cycle(1:9))(sample(9))