将count（）应用于数据帧中的每个因子变量

Question

I can use purrr::map() to get the mean of every column in a dataframe . Can I use any of the map functions in combination with count() to get counts for each categorical variable in a dataframe?

library(dplyr)
library(purrr)

mtcars %>% map(mean)

mtcars %>% mutate(am = factor(am, labels = c("auto", "manual")),
         vs = factor(vs, labels = c("V", "S"))) %>% select_if(is.factor) %>% 
map(count)

Answer 1

You can use the 'table' function instead of count:

mtcars %>% 
  mutate(
    am = factor(am, labels = c("auto", "manual")),
    vs = factor(vs, labels = c("V", "S"))
  ) %>% 
  select_if(is.factor) %>% 
  map(table)

#$`vs`

 #V  S 
#18 14 

#$am

  #auto manual 
    #19     13 

Answer 2

Almost there! Just need to specify the data in count :

mtcars %>% 
  mutate(
    am = factor(am, labels = c("auto", "manual")),
    vs = factor(vs, labels = c("V", "S"))
  ) %>% 
  select_if(is.factor) %>% 
  map(~count(data.frame(x = .x), x))