CODEWITHSUNDEEP
rcombinations
Samuel Perche
Samuel Perche

Reputation: 39

finding combinations of elements from two matrices

I would like a matrix of all the combinations of

matrix1 <- combinations(10,3)
matrix2 <- combinations(20,1)

i.e. we are choosing 3 numbers without repetition from a bag with numbers 1 to 10, then one number from 1 to 20

Upvotes: 0

Views: 36

Answers (2)

Jonas
Jonas

Reputation: 1810

Assuming combinations does something similar to utils::combn, you can use

matrix1 <- combn(10, 3)
matrix2 <- combn(20, 1)

pasted1 <- apply(matrix1,2,paste0,collapse=",")
pasted2 <- apply(matrix2,2,paste0,collapse=",")

expanded <- apply(expand.grid(pasted1,pasted2),1,paste0,collapse=",")

res <- lapply(strsplit(expanded,","),as.numeric)

Upvotes: 1

ThomasIsCoding
ThomasIsCoding

Reputation: 101618

Are you looking for something like this?

matrix1 <- combn(10, 3)
matrix2 <- combn(20, 1)

res <- c(
  outer(
    1:ncol(matrix1),
    1:ncol(matrix2),
    Vectorize(function(x, y) list(c(matrix1[, x], matrix2[, y])))
  )
)

Upvotes: 2

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