group_modify error with empty data frame #4421
Description
I came across an edge case today where group_modify gives a misleading error message if the input data frame is empty. It reports that the grouping variable was not found. I think the expected behavior would be to return an empty data frame, similar to summarize.
group_map returns an empty list given the same input.
library(dplyr)
mtcars %>%
group_by(cyl) %>%
filter(hp > 1000) %>%
group_modify(~.x)
#> Error: Column `cyl` is unknown
mtcars %>%
group_by(cyl) %>%
filter(hp > 1000) %>%
group_map(~.x)
#> list()
Created on 2019-06-12 by the reprex package (v0.3.0)
Session info
devtools::session_info()
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