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rpermutationpermute

How to calculate permutations of group labels with R?

Given a vector like:

labels <- c(1,2,3,3,3)

How to get all possible group relabelings? For this example:

1,2,3,3,3
1,3,2,2,2
2,1,3,3,3
2,3,1,1,1
3,1,2,2,2
3,2,1,1,1

I have been looking at the permute package but I don't see how to apply it to this case.

Solution

  • How about this solution

    labels <- c(1,2,3,3,3)
library(data.table)
a <- do.call(cbind, combinat::permn(unique(labels)))
data.table(a)[,lapply(.SD, function(x)x[labels]),]
#   V1 V2 V3 V4 V5 V6
#1:  1  1  3  3  2  2
#2:  2  3  1  2  3  1
#3:  3  2  2  1  1  3
#4:  3  2  2  1  1  3
#5:  3  2  2  1  1  3

    Or, just

    apply(a, 2, function(x) x[labels])
#     [,1] [,2] [,3] [,4] [,5] [,6]
#[1,]    1    1    3    3    2    2
#[2,]    2    3    1    2    3    1
#[3,]    3    2    2    1    1    3
#[4,]    3    2    2    1    1    3
#[5,]    3    2    2    1    1    3