In certain cases you only want a layer to include certain values of a factor. The `keep_levels()` function allows you to pass character values to be included in the layer. The others are ignored. **NOTE: Denominator calculation is unaffected by this function, see the examples on how to include this logic in your percentages'**

keep_levels(e, ...)



A count_layer object


Character values to count int he layer


The modified Tplyr layer object


library(dplyr) mtcars <- mtcars %>% mutate_all(as.character) t <- tplyr_table(mtcars, gear) %>% add_layer( group_count(cyl) %>% keep_levels("4", "8") %>% set_denom_where(cyl %in% c("4", "8")) ) %>% build()