Element wise concatenation of nested list

Question

I have a nested list

l1 <- letters
l2 <- 1:26
l3 <- LETTERS
list <- list(l1,l2,l3)

Is there an elegant way to concatenate all the elements in inner vectors to form one character vector (possibly using paste), the assumption is that all the inner vectors are of the same length.

I would like my final result to be

[1] "a1A"
[2] "b2B"
[3] "c3C"
[4] "d4D"
....
[26] "z26Z"

this one's perfect. Thanks! – Muzammil Aziz Sep 01 '18 at 20:25 — Muzammil Aziz, Sep 01 '18 at 20:25

score 1 · Answer 1 · answered Sep 01 '18 at 12:20

1

Try:

apply(sapply(list,paste0),1,paste0,collapse="")
[1] "a1A"  "b2B"  "c3C"  "d4D"  "e5E"  "f6F"  "g7G"  "h8H"  "i9I"  "j10J" "k11K" "l12L" "m13M" "n14N" "o15O" [16] "p16P" "q17Q" "r18R" "s19S" "t20T" "u21U" "v22V" "w23W" "x24X" "y25Y" "z26Z"

answered Sep 01 '18 at 12:20

Chriss Paul

1,101
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score 1 · Answer 2 · answered Sep 01 '18 at 12:20

user20650's solution is probably as elegant as you are going to get. But for what it's worth, here's a quick hack in dplyr:

library(dplyr)

ll <- list(l1,l2,l3) # I try not to use "list" as a name. Gets confusing sometimes.

as.data.frame(ll) %>% 
  mutate(x = paste0(.[[1]], .[[2]], .[[3]])) %>% 
  .$x

# returns
 [1] "a1A"  "b2B"  "c3C"  "d4D"  "e5E"  "f6F"  "g7G"  "h8H"  "i9I"  "j10J" "k11K" "l12L"
[13] "m13M" "n14N" "o15O" "p16P" "q17Q" "r18R" "s19S" "t20T" "u21U" "v22V" "w23W" "x24X"
[25] "y25Y" "z26Z"

Even easier: `purrr::pmap(ll, paste0)` ([see also here](https://stackoverflow.com/a/41489994/2204410)). — Jaap, Sep 01 '18 at 12:51

Element wise concatenation of nested list

2 Answers2