Convert an R data.frame with factors into a data.frame with dummies (non-factor columns unchanged)

factorsToDummies.R

library(magrittr)

factorsToDummies <- function(df)
# df: a data.frame.
# returns: a data.frame with non-factor columns unchanged
# and factor columns replaced by a series of dummies
# for each factor.
    lapply(df,
           function(x)
               if (x %>% is.factor %>% not) x else
                   lapply(levels(x),
                          function(y) (x==y) %>%
                              as.numeric)) %>%
    as.data.frame %>%
    set_names(lapply(names(df),
                     function(x)
                         if (df[[x]] %>% is.factor %>% not) x else
                             paste(x, '=', levels(df[[x]]))) %>%
                  unlist)