Writing a function that reads both column y and text "y" in str_remove

I'm writing a function in R for some code cleaning that involves removing some text in a string. I've got the following dataframe:

x <- c(1, 2, 3, 4, 5)
y <-c("y_a","y_b","y_c","y_d","y_e")
z <-c("z_f","z_g","z_h","z_i","z_j")
df <- (x, y, z)

And I'm trying to clear the y_ and z_ out of columns y and z respectively.

Normally I'd write it as

df <- df %>%
mutate(y=str_remove(y,"y_"))

But I want to write a function so I can repeat. Right now my function looks like:

remove_weird_letter <- function(LETTER) {
mutate(LETTER=str_remove(LETTER,"LETTER_"))
}

df <- remove_weird_letter(y)
df <- remove_weird_letter(z)

But it's not reading seeing "LETTER" as a reference to the object in the function, so it's not removing what it needs to. How do I modify my syntax so that it knows to both reference a column called LETTER and text containing LETTER?

Thank you!

Solution

Here is a way.
The function accepts a column and removes everything up to including the first underscore from the beginning of the strings.
Three examples are given.

suppressPackageStartupMessages(
  library(dplyr)
)

remove_weird_letter <- function(x) {
  pattern <- "^[^_]+_"
  stringr::str_remove(x, pattern)
}

x <- c(1, 2, 3, 4, 5)
y <-c("y_a","y_b","y_c","y_d","y_e")
z <-c("z_f","z_g","z_h","z_i","z_j")
x827402 <- paste0("x827402_", 1:5)
x19538 <- paste0("x19538_", 1:5)
x300004192 <- paste0("x300004192_", 1:5)
df <- data.frame(x, y, z, x827402, x19538, x300004192)

# remove column name from one column
df %>%
  mutate(y = remove_weird_letter(y))
#>   x y   z   x827402   x19538   x300004192
#> 1 1 a z_f x827402_1 x19538_1 x300004192_1
#> 2 2 b z_g x827402_2 x19538_2 x300004192_2
#> 3 3 c z_h x827402_3 x19538_3 x300004192_3
#> 4 4 d z_i x827402_4 x19538_4 x300004192_4
#> 5 5 e z_j x827402_5 x19538_5 x300004192_5

# remove column names from several columns
df %>%
  mutate(across(y:x300004192, ~ remove_weird_letter(.x)))
#>   x y z x827402 x19538 x300004192
#> 1 1 a f       1      1          1
#> 2 2 b g       2      2          2
#> 3 3 c h       3      3          3
#> 4 4 d i       4      4          4
#> 5 5 e j       5      5          5

# remove column names from several columns
df %>%
  mutate(across(y:x300004192, ~ remove_weird_letter(.x)))
#>   x y z x827402 x19538 x300004192
#> 1 1 a f       1      1          1
#> 2 2 b g       2      2          2
#> 3 3 c h       3      3          3
#> 4 4 d i       4      4          4
#> 5 5 e j       5      5          5

# remove column names from columns starting with "x"
df %>%
  mutate(across(starts_with("x"), ~ remove_weird_letter(.x)))
#>   x   y   z x827402 x19538 x300004192
#> 1 1 y_a z_f       1      1          1
#> 2 2 y_b z_g       2      2          2
#> 3 3 y_c z_h       3      3          3
#> 4 4 y_d z_i       4      4          4
#> 5 5 y_e z_j       5      5          5

^{Created on 2023-10-31 with reprex v2.0.2}