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

Using the lengthsfunction:

lengths(lapply(Testdata, unique))

# var_1 var_2 var_3 
#     1     1     3