Change column names in nested df using map function - r

Question

I am working on a project where I created a function to edit column names of a given df:
fix_names <- function(a, b, c) {
if (is.data.frame(a) == TRUE & is.character(b) == TRUE & is.character(c) == TRUE) {
str_replace_all(colnames(a), pattern = b, replacement = c)
} else {
return("invalid inputs")
}
}
And then I have a column, data, that contains four data frames. I am trying to rename the columns of all the data frames in data using my function above inside of a map function. It's successful in fixing the names, but I cannot figure out how to apply it to the df since the output is a list and the data frames are nested. Here's what I have:
map(.x = df$data, ~fix_names(., "OldName", "NewName"))
Thank you!
Edit: adding example df using mtcars
data(mtcars)
mtcars %>%
group_by(cyl) %>%
nest() -> nestMtcars
map(.x = nestMtcars$data, ~fix_names(., "mpg", "MPG"))

Answer 1

You could transpose the nested list to run the map function, and transpose it back to its original form :
library(stringr)
library(purrr)
fix_names <- function(a, b, c) {
if (is.data.frame(a) == TRUE & is.character(b) == TRUE & is.character(c) == TRUE) {
colnames(a) <- str_replace_all(colnames(a), pattern = b, replacement = c)
a
} else {
return("invalid inputs")
}
}
nestMtcars %>% transpose %>%
map(~{.x$data <- fix_names(.x$data,"mpg","MPG"); .x}) %>%
transpose
$cyl
$cyl[[1]]
[1] 6
$cyl[[2]]
[1] 4
$cyl[[3]]
[1] 8
$data
$data[[1]]
# A tibble: 7 x 10
MPG disp hp drat wt qsec vs am gear carb
<dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl>
1 21 160 110 3.9 2.62 16.5 0 1 4 4
2 21 160 110 3.9 2.88 17.0 0 1 4 4
3 21.4 258 110 3.08 3.22 19.4 1 0 3 1
4 18.1 225 105 2.76 3.46 20.2 1 0 3 1
5 19.2 168. 123 3.92 3.44 18.3 1 0 4 4
6 17.8 168. 123 3.92 3.44 18.9 1 0 4 4
7 19.7 145 175 3.62 2.77 15.5 0 1 5 6
$data[[2]]
# A tibble: 11 x 10
MPG disp hp drat wt qsec vs am gear carb
<dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl>
1 22.8 108 93 3.85 2.32 18.6 1 1 4 1
2 24.4 147. 62 3.69 3.19 20 1 0 4 2
3 22.8 141. 95 3.92 3.15 22.9 1 0 4 2
4 32.4 78.7 66 4.08 2.2 19.5 1 1 4 1
5 30.4 75.7 52 4.93 1.62 18.5 1 1 4 2
6 33.9 71.1 65 4.22 1.84 19.9 1 1 4 1
7 21.5 120. 97 3.7 2.46 20.0 1 0 3 1
8 27.3 79 66 4.08 1.94 18.9 1 1 4 1
9 26 120. 91 4.43 2.14 16.7 0 1 5 2
10 30.4 95.1 113 3.77 1.51 16.9 1 1 5 2
11 21.4 121 109 4.11 2.78 18.6 1 1 4 2
$data[[3]]
# A tibble: 14 x 10
MPG disp hp drat wt qsec vs am gear carb
<dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl>
1 18.7 360 175 3.15 3.44 17.0 0 0 3 2
2 14.3 360 245 3.21 3.57 15.8 0 0 3 4
3 16.4 276. 180 3.07 4.07 17.4 0 0 3 3
4 17.3 276. 180 3.07 3.73 17.6 0 0 3 3
5 15.2 276. 180 3.07 3.78 18 0 0 3 3
6 10.4 472 205 2.93 5.25 18.0 0 0 3 4
7 10.4 460 215 3 5.42 17.8 0 0 3 4
8 14.7 440 230 3.23 5.34 17.4 0 0 3 4
9 15.5 318 150 2.76 3.52 16.9 0 0 3 2
10 15.2 304 150 3.15 3.44 17.3 0 0 3 2
11 13.3 350 245 3.73 3.84 15.4 0 0 3 4
12 19.2 400 175 3.08 3.84 17.0 0 0 3 2
13 15.8 351 264 4.22 3.17 14.5 0 1 5 4
14 15 301 335 3.54 3.57 14.6 0 1 5 8