I grouped my dataset and saved it without ungrouping it.
Then I loaded it and I no longer remember what variable was the grouping variable.
class (mydata) give:
"grouped_df" "tbl_df" "tbl" "data.frame"
By what operation can I identify the grouping variable?
You can use group_vars or groups -
library(dplyr)
res <- mtcars %>% group_by(cyl, am)
group_vars(res)
#[1] "cyl" "am"
groups(res)
#[[1]]
#cyl
#[[2]]
#am
We can use cur_group
library(dplyr)
mtcars %>%
group_by(cyl, am) %>%
summarise(out = names(cur_group()))