CODEWITHSUNDEEP
r
Jack
Jack

Reputation: 85

How to remove a list of lists from another list of lists in R?

I have a two lists of lists generated by the following function:

 a <- replicate(10, sample(1:100,size=10), simplify=FALSE)
 b <- replicate(10, sample(1:100,size=10), simplify=FALSE)

Is there a way to remove numbers in 'b' lists from corresponding lists in 'a' so if:

a[1] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}
b[1] = {2, 3, 4, 5, 6, 7, 8, 9, 10, 11}

then the output would ideally be 

c[1] = {1}

I was trying to do something like this but it didn't work: 

for(i in 1:10){
index <- which( names(a[i]) %in% b[i])
a[i][-index]
}

Thanks ahead of time.

Upvotes: 1

Views: 166

Answers (2)

Yuriy Saraykin
Yuriy Saraykin

Reputation: 8880

additional solution

a <- list(c(1:10))
b <- list(c(2:11))

purrr::map2(.x = a, .y = b, .f = dplyr::setdiff)

Upvotes: 1

akrun
akrun

Reputation: 886998

We can use Map with setdiff

Map(setdiff, b, a)

If it is the opposite

Map(setdiff, a, b)

Or another option is vsetdiff to preserve duplicate elements

library(vecsets)
Map(vsetdiff, a, b)

Or use %in% and negate (!)

Map(function(x, y) x[!x %in% y], a, b)

Or using for loop

for(i in seq_along(a)) a[[i]] <- a[[i]][!a[[i]] %in% b[[i]]]

Upvotes: 1

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