Function to coerce strings given a condition

Question

I simply want to coerce as numbers --i.e., to apply as.numeric to--any columns which have a 1 as their first entry (i.e., a character). So I would expect to turn:

tibble(a = c("1", "2"), b = c("Fred", "Kevin"), c = 1:2)

into

tibble(a = 1:2, b = c("Fred", "Kevin"), c = 1:2)

Answer 1

You could use dplyr:

library(dplyr)

data %>% 
  mutate(across(where(~ first(.x) == "1" & !is.na(first(.x))), as.numeric)).

returns

# A tibble: 2 x 5
      a b         c     d e    
  <dbl> <chr> <dbl> <dbl> <lgl>
1     1 Fred      1     1 NA    
2     2 Kevin     2     3 NA   

Data

data <- tibble(a = c("1", "2"), 
               b = c("Fred", "Kevin"), 
               c = 1:2, 
               d = c("1", "3"), 
               e = c(NA, NA))