[ARROW-17738] [R] dplyr::compute should convert from grouped arrow_dplyr_query to arrow Table

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 9.0.0
• Fix Version/s: 10.0.0
• Component/s: R
• Labels: pull-request-available
• External issue URL: https://github.com/apache/arrow/issues/32973
• Assignee: SHIMA Tatsuya
• Reporter: SHIMA Tatsuya
• Created: 15/Sep/22 13:31
• Updated: 11/Jan/23 11:52
• Resolved: 07/Oct/22 19:20

Description

It is expected that dplyr::compute() will perform the calculation on the arrow dplyr query and convert it to a Table, but it does not seem to work correctly for grouped arrow dplyr queries and does not result in a Table.

mtcars |> arrow::arrow_table() |> dplyr::group_by(cyl) |> dplyr::compute() |> class()
#> [1] "arrow_dplyr_query"
mtcars |> arrow::arrow_table() |> dplyr::group_by(cyl) |> dplyr::ungroup() |> dplyr::compute() |> class()
#> [1] "Table"        "ArrowTabular" "ArrowObject"  "R6"

as_arrow_table() works fine.

mtcars |> arrow::arrow_table() |> dplyr::group_by(cyl) |> class()
#> [1] "arrow_dplyr_query"
mtcars |> arrow::arrow_table() |> dplyr::group_by(cyl) |> dplyr::compute() |> class()
#> [1] "arrow_dplyr_query"
mtcars |> arrow::arrow_table() |> dplyr::group_by(cyl) |> dplyr::collect(FALSE) |> class()
#> [1] "arrow_dplyr_query"
mtcars |> arrow::arrow_table() |> dplyr::group_by(cyl) |> arrow::as_arrow_table() |> class()
#> [1] "Table"        "ArrowTabular" "ArrowObject"  "R6"

It seems to revert to arrow dplyr query in the following line.
https://github.com/apache/arrow/blob/7cfdfbb0d5472f8f8893398b51042a3ca1dd0adf/r/R/dplyr-collect.R#L73-L75

 

Issue Links

• is related to: ARROW-17737 [R] Groups before conversion to a Table must not be restored after `collect()`
• links to: GitHub Pull Request #14160