How can i combine rowise data frames within a list?

Question

Suppose I have the following two lists. I want to take the first entry of list2 and combine this data frame to list1. Doing this for all entries.

data1 <- data.frame(id = 1:6,                                  
                    x1 = c(5, 1, 4, 9, 1, 2),
                    x2 = c("A", "Y", "G", "F", "G", "Y"))
data2 <- data.frame(id = 4:9,                                  
                    y1 = c(3, 3, 4, 1, 2, 9),
                    y2 = c("a", "x", "a", "x", "a", "x"))
l1 <- list(data1, data2)
l2 <- list(data1, data2)

What I expect as a result is one list of length 2. Each entry should be a data frame with 12 rows and 3 columns.

Answer 1

Another possible solution, based on mapply:

mapply(rbind, l1, l2, SIMPLIFY = F)

#> [[1]]
#>    id x1 x2
#> 1   1  5  A
#> 2   2  1  Y
#> 3   3  4  G
#> 4   4  9  F
#> 5   5  1  G
#> 6   6  2  Y
#> 7   1  5  A
#> 8   2  1  Y
#> 9   3  4  G
#> 10  4  9  F
#> 11  5  1  G
#> 12  6  2  Y
#> 
#> [[2]]
#>    id y1 y2
#> 1   4  3  a
#> 2   5  3  x
#> 3   6  4  a
#> 4   7  1  x
#> 5   8  2  a
#> 6   9  9  x
#> 7   4  3  a
#> 8   5  3  x
#> 9   6  4  a
#> 10  7  1  x
#> 11  8  2  a
#> 12  9  9  x

Answer 2

We may use Map with rbind to rbind the corresponding data.frame elements from both lists

Map(rbind, l1, l2)

-output

[[1]]
   id x1 x2
1   1  5  A
2   2  1  Y
3   3  4  G
4   4  9  F
5   5  1  G
6   6  2  Y
7   1  5  A
8   2  1  Y
9   3  4  G
10  4  9  F
11  5  1  G
12  6  2  Y

[[2]]
   id y1 y2
1   4  3  a
2   5  3  x
3   6  4  a
4   7  1  x
5   8  2  a
6   9  9  x
7   4  3  a
8   5  3  x
9   6  4  a
10  7  1  x
11  8  2  a
12  9  9  x

---

Or using map2 from purrr

library(purrr)
library(dplyr)
map2(l1, l2, bind_rows)