ramhiser

library(dplyr)
iris_char <- iris %>%
  mutate(Species=as.character(Species),
         char_column=sample(letters[1:5], nrow(iris), replace=TRUE))
sum(sapply(iris_char, is.character)) # 2

iris_factor <- iris_char %>%
  mutate_if(sapply(iris_char, is.character), as.factor)
# Sepal.Length  Sepal.Width Petal.Length  Petal.Width      Species  char_column 
# "numeric"    "numeric"    "numeric"    "numeric"  "character"  "character"