rename column in list of data.frames with map2()

tidyverse
1

Hello,

I have a list of data.frames with a common column name and would like to give the column a unique name for each data.frame. I attempted this using map2 in the example below, but I've unintentionally simply renamed the cyl column to .y My goal is for the cyl column to be renamed to 4 cyl in the first data.frame, 6 cyl in the second, etc.

Thanks

 library(tidyverse)
 
 mtcars_dflist <- mtcars %>% group_split(cyl)
 
 new_labs <- c("4 cyl", "6 cyl", "8 cyl")
 
 map2(mtcars_dflist, new_labs, ~rename(.x, .y = .data$cyl ))
#> [[1]]
#> # A tibble: 11 x 11
#>      mpg    .y  disp    hp  drat    wt  qsec    vs    am  gear  carb
#>    <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl>
#>  1  22.8     4 108      93  3.85  2.32  18.6     1     1     4     1
#>  2  24.4     4 147.     62  3.69  3.19  20       1     0     4     2
#>  3  22.8     4 141.     95  3.92  3.15  22.9     1     0     4     2
#>  4  32.4     4  78.7    66  4.08  2.2   19.5     1     1     4     1
#>  5  30.4     4  75.7    52  4.93  1.62  18.5     1     1     4     2
#>  6  33.9     4  71.1    65  4.22  1.84  19.9     1     1     4     1
#>  7  21.5     4 120.     97  3.7   2.46  20.0     1     0     3     1
#>  8  27.3     4  79      66  4.08  1.94  18.9     1     1     4     1
#>  9  26       4 120.     91  4.43  2.14  16.7     0     1     5     2
#> 10  30.4     4  95.1   113  3.77  1.51  16.9     1     1     5     2
#> 11  21.4     4 121     109  4.11  2.78  18.6     1     1     4     2
#> 
#> [[2]]
#> # A tibble: 7 x 11
#>     mpg    .y  disp    hp  drat    wt  qsec    vs    am  gear  carb
#>   <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl>
#> 1  21       6  160    110  3.9   2.62  16.5     0     1     4     4
#> 2  21       6  160    110  3.9   2.88  17.0     0     1     4     4
#> 3  21.4     6  258    110  3.08  3.22  19.4     1     0     3     1
#> 4  18.1     6  225    105  2.76  3.46  20.2     1     0     3     1
#> 5  19.2     6  168.   123  3.92  3.44  18.3     1     0     4     4
#> 6  17.8     6  168.   123  3.92  3.44  18.9     1     0     4     4
#> 7  19.7     6  145    175  3.62  2.77  15.5     0     1     5     6
#> 
#> [[3]]
#> # A tibble: 14 x 11
#>      mpg    .y  disp    hp  drat    wt  qsec    vs    am  gear  carb
#>    <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl>
#>  1  18.7     8  360    175  3.15  3.44  17.0     0     0     3     2
#>  2  14.3     8  360    245  3.21  3.57  15.8     0     0     3     4
#>  3  16.4     8  276.   180  3.07  4.07  17.4     0     0     3     3
#>  4  17.3     8  276.   180  3.07  3.73  17.6     0     0     3     3
#>  5  15.2     8  276.   180  3.07  3.78  18       0     0     3     3
#>  6  10.4     8  472    205  2.93  5.25  18.0     0     0     3     4
#>  7  10.4     8  460    215  3     5.42  17.8     0     0     3     4
#>  8  14.7     8  440    230  3.23  5.34  17.4     0     0     3     4
#>  9  15.5     8  318    150  2.76  3.52  16.9     0     0     3     2
#> 10  15.2     8  304    150  3.15  3.44  17.3     0     0     3     2
#> 11  13.3     8  350    245  3.73  3.84  15.4     0     0     3     4
#> 12  19.2     8  400    175  3.08  3.84  17.0     0     0     3     2
#> 13  15.8     8  351    264  4.22  3.17  14.5     0     1     5     4
#> 14  15       8  301    335  3.54  3.57  14.6     0     1     5     8

Created on 2022-11-10 by the reprex package (v2.0.1)

2

Below is one approach that uses the column index to rename the column.

library(tidyverse)

mtcars_dflist <- mtcars %>% group_split(cyl)

new_labs <- c("4 cyl", "6 cyl", "8 cyl")

rename_function = function(.x, .y) {
  names(.x)[names(.x) == 'cyl'] = .y
  .x
  }

map2(.x = mtcars_dflist,
     .y = new_labs,
     ~rename_function(.x, .y)
     )
#> [[1]]
#> # A tibble: 11 × 11
#>      mpg `4 cyl`  disp    hp  drat    wt  qsec    vs    am  gear  carb
#>    <dbl>   <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl>
#>  1  22.8       4 108      93  3.85  2.32  18.6     1     1     4     1
#>  2  24.4       4 147.     62  3.69  3.19  20       1     0     4     2
#>  3  22.8       4 141.     95  3.92  3.15  22.9     1     0     4     2
#>  4  32.4       4  78.7    66  4.08  2.2   19.5     1     1     4     1
#>  5  30.4       4  75.7    52  4.93  1.62  18.5     1     1     4     2
#>  6  33.9       4  71.1    65  4.22  1.84  19.9     1     1     4     1
#>  7  21.5       4 120.     97  3.7   2.46  20.0     1     0     3     1
#>  8  27.3       4  79      66  4.08  1.94  18.9     1     1     4     1
#>  9  26         4 120.     91  4.43  2.14  16.7     0     1     5     2
#> 10  30.4       4  95.1   113  3.77  1.51  16.9     1     1     5     2
#> 11  21.4       4 121     109  4.11  2.78  18.6     1     1     4     2
#> 
#> [[2]]
#> # A tibble: 7 × 11
#>     mpg `6 cyl`  disp    hp  drat    wt  qsec    vs    am  gear  carb
#>   <dbl>   <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl>
#> 1  21         6  160    110  3.9   2.62  16.5     0     1     4     4
#> 2  21         6  160    110  3.9   2.88  17.0     0     1     4     4
#> 3  21.4       6  258    110  3.08  3.22  19.4     1     0     3     1
#> 4  18.1       6  225    105  2.76  3.46  20.2     1     0     3     1
#> 5  19.2       6  168.   123  3.92  3.44  18.3     1     0     4     4
#> 6  17.8       6  168.   123  3.92  3.44  18.9     1     0     4     4
#> 7  19.7       6  145    175  3.62  2.77  15.5     0     1     5     6
#> 
#> [[3]]
#> # A tibble: 14 × 11
#>      mpg `8 cyl`  disp    hp  drat    wt  qsec    vs    am  gear  carb
#>    <dbl>   <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl>
#>  1  18.7       8  360    175  3.15  3.44  17.0     0     0     3     2
#>  2  14.3       8  360    245  3.21  3.57  15.8     0     0     3     4
#>  3  16.4       8  276.   180  3.07  4.07  17.4     0     0     3     3
#>  4  17.3       8  276.   180  3.07  3.73  17.6     0     0     3     3
#>  5  15.2       8  276.   180  3.07  3.78  18       0     0     3     3
#>  6  10.4       8  472    205  2.93  5.25  18.0     0     0     3     4
#>  7  10.4       8  460    215  3     5.42  17.8     0     0     3     4
#>  8  14.7       8  440    230  3.23  5.34  17.4     0     0     3     4
#>  9  15.5       8  318    150  2.76  3.52  16.9     0     0     3     2
#> 10  15.2       8  304    150  3.15  3.44  17.3     0     0     3     2
#> 11  13.3       8  350    245  3.73  3.84  15.4     0     0     3     4
#> 12  19.2       8  400    175  3.08  3.84  17.0     0     0     3     2
#> 13  15.8       8  351    264  4.22  3.17  14.5     0     1     5     4
#> 14  15         8  301    335  3.54  3.57  14.6     0     1     5     8

Created on 2022-11-10 with reprex v2.0.2.9000

3

Very cool--works great. Thanks so much!

4

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