CODEWITHSUNDEEP
r
Yao Tong
Yao Tong

Reputation: 1

How to get the combinations of multiple vectors in R

I have a data frame x. I want to get the pairwise combinations of all rows, like (x[1,], x[2,), (x[1,], x[3,]), (x[2,], x[3,]). Here I take each row as an entirety. I tried functions like combn, but it gave me the combinations of all elements in all rows.

Upvotes: 0

Views: 153

Answers (2)

jl5000
jl5000

Reputation: 45

The crossing() function from the tidyr package may help you. (The link contains a StackOverflow example.)

Upvotes: 0

Karsten W.
Karsten W.

Reputation: 18420

I think with combn you are on the right track:

x <- data.frame(a=sample(letters, 10), b=1:10, c=runif(10), stringsAsFactors=FALSE)
ans <- combn(nrow(x), 2, FUN=function(sub) x[sub,], simplify=FALSE)

Now ans is a list of (in this case 45, in general choose(nrow(x), 2)) data.frames with two rows each.

Upvotes: 1

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