CODEWITHSUNDEEP
rlistvectorcomparisonsubset
dcernee
dcernee

Reputation: 43

Check if a vector is a superset of another vector in R

I have the following list of vectors:

a <- c(1,2,4,5,6,7,8,9)
b <- c(1,2,4,5)
c <- c(1,2,3,10,11,12,13,14)
d <- c(1,2,3,10,15,16,17,18,19)
e <- c(1,2,3,10,15,16)
f <- list(a,b,c,d,e)

Right now, I can do something like this

is_subset <- vector()
for(i in 1:length(f)) {
  is_subset <- c(is_subset, all(unlist(f[i]) %in% unlist(f[-i])))
}
f[!is_subset]

and get a list containing every vector that is not a subset of any other vector from the original list:

[[1]]
[1] 1 2 4 5 6 7 8 9

[[2]]
[1]  1  2  3 10 11 12 13 14

[[3]]
[1]  1  2  3 10 15 16 17 18 19

However, what I really want is to subset the list so that it includes only those vectors that are not supersets of other vectors from the list -- i.e., the desired output should look like this:

[[1]]
[1] 1 2 4 5

[[2]]
[1]  1  2  3 10 11 12 13 14

[[3]]
[1]  1  2  3 10 15 16

How can I do this in R?

Upvotes: 2

Views: 445

Answers (1)

Tim Biegeleisen
Tim Biegeleisen

Reputation: 522787

In the code snippet below, I compare each vector in your list against every other vector using %in%. If the sum of each comparison vector comes up non zero more than once, then the vector is a superset of another vector. Note that we expect a single comparison to match exactly, namely the comparison of a vector against itself.

out <- sapply(f, function(x) {
    res <- lapply(f, function(y) {
        return(sum(!(y %in% x)))
    })
    return(sum(res > 0) == length(res) - 1)
})

f[out]
[[1]]
[1] 1 2 4 5

[[2]]
[1]  1  2  3 10 11 12 13 14

[[3]]
[1]  1  2  3 10 15 16

Demo

Upvotes: 1

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