I have a list of 4 lists with the same name:
lst1 <-
list(list(c(1,2,3)),list(c(7,8,9)),list(c(4,5,6)),list(c(10,11,12)))
names(lst1) <- c("a","b","a","b")
I want to combine the sub lists together (first "a" with second "a", first "b" with second "b":
result <- list(list(c(1,2,3,4,5,6)),list(c(7,8,9,10,11,12)))
names(result) <- c("a","b")
I have tried multiple things, but can't figure it out.
Since lst1["a"] isn't going to give us all the elements of lst1 named a, we are going to need to work with names(lst1). One base R approach would be
nm <- names(lst1)
result <- lapply(unique(nm), function(n) unname(unlist(lst1[nm %in% n])))
names(result) <- unique(nm)
result
# $a
# [1] 1 2 3 4 5 6
#
# $b
# [1] 7 8 9 10 11 12
Another option is to use unlist first and then split the resulting vector.
vec <- unlist(lst1)
split(unname(vec), sub("\\d+$", "", names(vec)))
#$a
#[1] 1 2 3 4 5 6
#$b
#[1] 7 8 9 10 11 12
Just group the elements with the same name and unlist them:
tapply(lst1,names(lst1),FUN=function(x) unname(unlist(x)))