Trim levels of another variable from each facet (post-processing split step)
trim_levels_in_facets(innervar)A function suitable for use in the pre (list) argument of make_split_fun.
(character)
the variable(s) to trim (remove unobserved levels) independently within each facet.
make_split_fun()
Other make_custom_split:
add_combo_facet(),
drop_facet_levels(),
make_split_fun(),
make_split_result()