Combining list of character vectors with different sizes into a single dataframe

Question

I would like to combine a list of character vectors into a single data frame. For example, I want

list(A=c("123","456"), B=c("789"), C=c("000"))

to become:

  label val
1     A 123
2     A 456
3     B 789
4     C 000

I came up with the following. It works, but it seems clunky. Is there a more elegant way to do the above?

l <- list(A=c("123","456"), B=c("789"), C=c("000"))
res <- lapply(names(l), function(x) { 
    data.frame(label=rep(x, length(l[[x]])), val=l[[x]], 
        stringsAsFactors = F) })
do.call("rbind", res)

lkq · Answer 1 · 2019-02-02T20:13:29.523

2

library(tidyverse)

test <- list(A=c("123","456"), B=c("789"), C=c("000"))
enframe(test, "label", "val") %>% unnest

edited Feb 02 '19 at 20:13

answered Feb 02 '19 at 20:11

lkq

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what package is enframe/unnest? – patrickmdnet Feb 02 '19 at 20:13
@patrickmdnet I updated the answer – lkq Feb 02 '19 at 20:13

score 2 · Accepted Answer · answered Feb 02 '19 at 20:14

2

You can use good old fashioned base R.

stack(l)
#   values ind
# 1    123   A
# 2    456   A
# 3    789   B
# 4    000   C

answered Feb 02 '19 at 20:14

Rich Scriven

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thanks! did not know about `stack()`; I just figured out that `reshape2::melt` works as well. – patrickmdnet Feb 02 '19 at 20:15
1

reshape2 is crapy library. use tidyr instead – Aleksandr Feb 02 '19 at 20:19

Combining list of character vectors with different sizes into a single dataframe

2 Answers2