Remove/reorder levels

refactor(x, levs = levels(x), repl = NA)

Arguments

x: Character or Factor
levs: Set of levels to use
repl: String (or NA) used to replace missing levels

Details

Keep only a specific set of levels in a factor. By removing levels the base for comparison in, e.g., regression analysis, becomes the first level. To relabel the base use, for example, repl = 'other'

Examples

refactor(diamonds$cut, c("Premium", "Ideal")) %>% head()
#> [1] Ideal   <NA>    <NA>    Ideal   Premium Ideal  
#> Levels: Premium Ideal
refactor(diamonds$cut, c("Premium", "Ideal"), "Other") %>% head()
#> [1] Ideal   Other   Other   Ideal   Premium Ideal  
#> Levels: Other Premium Ideal