Using mutate_each with functions that aren't window functions

mutate-each.R

library(ggplot2)
library(magrittr)

glimpse(mpg) # note that `trans` and `drv`, for example, are factors

coerce_factors_to_characters <- function (x) {
  return(
    ifelse(
      is.factor(x),
      as.character(x),
      x
    )
  )
}

# After the piping, `trans` and `drv` are character vectors,
# which is what I wanted.
# Note that my function wasn't, at least I don't think,
# a window function :-). Note also the cheat-sheet *only* says:
# 
# > dplyr::mutate_each(iris, funs(min_rank)) 
# >   Apply *window* function to each column.
#
# (my emphasis added)
mpg %>% 
  mutate_each(funs(coerce_factors_to_characters)) %>% 
  glimpse()