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Permute a vector of data

Source: R/permutations.R
permutations.Rd

permutations() generates permutations from a specified design and applies them to the values in a supplied vector. Each row of the returned object is one permutation of x.

Usage

permutations(x, nset, control = how(), check = TRUE, quietly = FALSE)

# S3 method for class 'permutations'
print(x, ...)

# S3 method for class 'permutations'
as.matrix(x, ...)

Arguments

x

A non-empty, one-dimensional atomic vector to permute. Factors are supported and are returned using their character labels.

nset

Numeric; the number of permutations to generate. If missing, the number is taken from control.

control

An object of class "how" describing a valid permutation design.

check

Logical; should the permutation design be checked by check()?

quietly

Logical; should messages from checking the design be suppressed?

...

Arguments passed to other methods.

Value

An object of class "permutations", inheriting from "matrix". Rows are permutations and columns correspond to the elements of x. The object has control and seed attributes containing the checked design and the random-number seed at the start of permutation generation.

as.matrix() returns an ordinary matrix with the permutation metadata removed.

Details

By default, the permutation design is checked in the same way as for shuffleSet(). Consequently, the number of rows returned can differ from nset when the design requests complete enumeration or when there are few possible permutations. Set check = FALSE to always request exactly nset permutations, which need not be unique.

See also

shuffleSet() for generating permutation indices and how() for specifying permutation designs.

Examples

set.seed(1)
permutations(letters[1:5], nset = 3, check = FALSE)
#> No. of Permutations: 3
#> No. of Samples: 5 (Randomised)
#> 
#>    1   2   3   4   5  
#> p1 "b" "e" "d" "c" "a"
#> p2 "e" "d" "b" "c" "a"
#> p3 "b" "a" "c" "d" "e"

## Restricted permutations of data from a time series
control <- how(within = Within(type = "series"))
permutations(c(10, 20, 30, 40, 50), nset = 3,
             control = control, check = FALSE)
#> No. of Permutations: 3
#> No. of Samples: 5 (Sequence)
#> 
#>     1  2  3  4  5
#> p1 40 50 10 20 30
#> p2 50 10 20 30 40
#> p3 10 20 30 40 50