I often want to match the classes between two data.frames, for instance when you lose column class information by moving between wide and long formats. Here is a convenience function to do that.

classify.R

classify <- function(value, function_char){
  fun <- get(paste0("as.", function_char))
  fun(value)
}

mtcars_char[] <- map(mtcars_char, as.character)
map(mtcars_char, class)
mtcars_char[] <- map2(mtcars_char, 
                      map_chr(mtcars, class),
                      ~classify(.x, .y))
map(mtcars_char, class)