Count unique values for every column

Question

I would like to return the count of the unique values for every column in a table. For example, if I have the table:

 Testdata <- data.frame(var_1 = c(\"a         


        

Answer 1

library(purrr)
Testdata %>% map_dbl(n_distinct)
var_1 var_2 var_3 
    1     1     3 

# in your format
Testdata %>% map_dbl(n_distinct)%>%melt(value.name = "unique_counts")
      unique_counts
var_1             1
var_2             1
var_3             3