(Internal) Label the legend with the percent of missing data

miss_guide_label is an internal function to label the legend of vis_miss.

expect_guide_label(x)

Arguments

x	is a dataframe passed from vis_miss(x).

Value

a tibble with two columns p_miss_lab and p_pres_lab, containing the labels to use for present and missing. A dataframe is returned because I think it is a good style habit compared to a list.