Details
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Bug
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Status: Resolved
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Major
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Resolution: Fixed
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7.0.0
Description
Unless grouped before `dplyr::count` returns a ungrouped data.frame. The arrow implement preserves the grouping variables:
library(arrow, warn.conflicts = FALSE) library(dplyr, warn.conflicts = FALSE) tf1 <- tempfile() dir.create(tf1) starwars |> write_dataset(tf1) # no group ---------------------------------------------------------------- ## dplyr behaviour count_dplyr_no_group <- starwars %>% count(gender, homeworld, species) group_vars(count_dplyr_no_group) #> character(0) ## arrow behaviour count_arrow_no_group <- open_dataset(tf1) %>% count(gender, homeworld, species) %>% collect() group_vars(count_arrow_no_group) #> [1] "gender" "homeworld"
If I am correct that this is a undesired behaviour I think it can be fixed here using this patch:
count.arrow_dplyr_query <- function(x, ..., wt = NULL, sort = FALSE, name = NULL) {
if (!missing(...)) {
out <- dplyr::group_by(x, ..., .add = TRUE)
} else {
out <- x
}
out <- dplyr::tally(out, wt = {{ wt }}, sort = sort, name = name)
gv <- dplyr::group_vars(x)
if (rlang::is_empty(gv)) {
out <- dplyr::ungroup(out)
} else {
# Restore original group vars
out$group_by_vars <- gv
}
out
}
I can submit a PR with some tests if that would be helpful.
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