Get a named vector of column indices for the grouping variables in a grouped data frame

Constructed a named vector of indices equivalent to the vectors produced by tidyselect::eval_select, but for the grouping variables in an object of class "grouped_df".

Usage

groups_colnums(data)

Arguments

data

A data frame.

Value

A named integer vector.

Details

If data is not grouped, then groups_colnums returns a zero-length vector.

Examples

library(dplyr)
df <- data.frame(x = 1:4,
                 g = c(1, 1, 2, 2))
groups_colnums(df)
#> named integer(0)
df <- group_by(df, g)
groups_colnums(df)
#> g 
#> 2