Sum of two lists

list, matrix, r

Solution

This is a typical case for the `mapply` function:

mapply("+", l1, l2, SIMPLIFY = FALSE)

Or slightly more concisely using `Map`, which is just `mapply` with different defaults.

Map("+", l1, l2)

Problem

How can I generally take the sum of the elements of two lists that contain conformable matrices? ``` l1<-list(matrix(1,3,3),matrix(2,3,3)) l2<-list(matrix(3,3,3),matrix(4,3,3)) ``` where the sum is defined as: ``` l3<-list(l1[[1]]+l2[[1]],l1[[2]]+l2[[2]]) ``` and 'generally' implies matrices of any size and lists of any length.

Original source