fct_drop: Drop unused levels
In sindribaldur/poorcats: Tools for Working with Categorical Variables (Factors)

Description Usage Arguments See Also Examples

Compared to base::droplevels(), does not drop NA levels that have values.

1	fct_drop(f, only)

`f`	A factor (or character vector).
`only`	A character vector restricting the set of levels to be dropped. If supplied, only levels that have no entries and appear in this vector will be removed.

fct_expand() to add additional levels to a factor.

f <- factor(c("a", "b"), levels = c("a", "b", "c"))
f
fct_drop(f)

# Set only to restrict which levels to drop
fct_drop(f, only = "a")
fct_drop(f, only = "c")