CODEWITHSUNDEEP
r
Linens
Linens

Reputation: 7942

R operating on lists within lists

In R, I can add 1 to each element of a list by doing alist<-alist +1. But what if I have something like alist<-list(list(1,2,3),list(2,3,4)). Is there some way to add 1 to each element of the sublist without using a loop?

Upvotes: 1

Views: 798

Answers (2)

Aaron - mostly inactive
Aaron - mostly inactive

Reputation: 37754

I just learned about this yesterday; it may be useful to others in similar situations; [[ allows for recursive indexing into lists, like this.

> alist[[c(1,2)]]
[1] 2

Upvotes: 5

daroczig
daroczig

Reputation: 28632

In the question list was written but the example showed a vector. I think the OP meant this:

alist <- list(list(1, 2, 3), list(2, 3, 4))

Instead of a loop you could use the recursive version of lapply, see: ?rapply.

> rapply(alist, function(x) x+1, how = "list" )
[[1]]
[[1]][[1]]
[1] 2

[[1]][[2]]
[1] 3

[[1]][[3]]
[1] 4


[[2]]
[[2]][[1]]
[1] 3

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

[[2]][[3]]
[1] 5

Upvotes: 8

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