Output the number of levels of all factors in a dataframe

I'm attempting to create a list or df that contains, for all factors within a data frame, the number of levels of the factor. So, it appears I need to first identify the factors (using `is.factor()`) and then count the number of levels for each (using `length()`) I was using `sapply`, but can't get what I am looking for. Any help would be appreciated. Here's what I've done so far: ``` fac <- sapply(cf_nm, function(x) is.factor(x) ) fac <- cf_nm[fac] ``` And I could simply count the levels here - but I was hoping for a more eloquent way of doing what I'd like.