group_by(.drop =)

[romainfrancois]

This is not ready yet, I've only so far just added the drop argument, it currently does nothing useful.

[romainfrancois]

closes #4061

[romainfrancois]

I've tried to follow .drop around (joins, implicit group by, count, ...) but I might be missing a few places.

it is stored as an attribute of the grouping structure

library(dplyr)
#> 
#> Attaching package: 'dplyr'
#> The following objects are masked from 'package:stats':
#> 
#>     filter, lag
#> The following objects are masked from 'package:base':
#> 
#>     intersect, setdiff, setequal, union

tibble(
  x = 1:2, 
  f = factor(c("a", "b"), levels = c("a", "b", "c"))
) %>% 
  group_by(f, .drop = TRUE) %>% 
  group_data() %>% 
  str()
#> Classes 'tbl_df', 'tbl' and 'data.frame':    2 obs. of  2 variables:
#>  $ f    : Factor w/ 3 levels "a","b","c": 1 2
#>  $ .rows:List of 2
#>   ..$ : int 1
#>   ..$ : int 2
#>  - attr(*, ".drop")= logi TRUE

The unexported group_drops() says if the data drops.

[hadley]

The overall structure looks good, but someone else needs to do a careful reading of the code. @lionel-?

[hadley]

Can we just @inheritParams these?

[romainfrancois]

🤔 it's add on group_by() and .add on group_by_*() I can :

• document .add here (probably, but that's kind of bad)
• switch to .add in group_by() (probably not)
• switch to add in group_by_*() (I guess not either)

[lionel-]

I'll take a look tomorrow.

[krlmlr]

Thanks, looks good. I'll try running this PR against the tests as defined in v0.7.8, hope there are now few failing tests if any.

[romainfrancois]

Should group_by have both .add and add for some time and then we slowly remove add ?

group_by <- function(.data, ..., add = FALSE, .add = add, .drop = FALSE) {
  ...
}

[hadley]

@romainfrancois we should tackle that in a separate PR, and it can wait until 0.9.0.

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