Programmatically dropping a `group_by` field in dplyr

Question

I\'m writing functions that take in a data.frame and then do some operations. I need to add and subtract items from the group_by criteria in order to g

Answer 1

Maybe something like this to remove grouping variables from the end of the list back:

grouped %>% 
 group_by(b, add=TRUE) -> grouped
grouped %>% group_by_at(.vars = group_vars(.)[-2])

or use head or tail or something on the output from group_vars for more control.

It would be interesting to have this sort of utility function available more generally:

peel_groups <- function(.data,n){
  .data %>%
    group_by_at(.vars = head(group_vars(.data),-n))
}

A more thought out version would likely include more careful checks on n being out of bounds.