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https://issues.apache.org/jira/browse/ARROW-17738?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17606157#comment-17606157
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Neal Richardson commented on ARROW-17738:
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They are evaluated and converted to Tables, but then if there are groups,
group_by is called on the Table, which results in an arrow_dplyr_query object
containing the Table. So, yes, this was intentional. Do you have a use case
where this is a problem?
> [R] dplyr::compute should convert from grouped arrow_dplyr_query to arrow
> Table
> -------------------------------------------------------------------------------
>
> Key: ARROW-17738
> URL: https://issues.apache.org/jira/browse/ARROW-17738
> Project: Apache Arrow
> Issue Type: Bug
> Components: R
> Affects Versions: 9.0.0
> Reporter: SHIMA Tatsuya
> Assignee: SHIMA Tatsuya
> Priority: Major
> Labels: pull-request-available
> Time Spent: 0.5h
> Remaining Estimate: 0h
>
> 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.
> {code:r}
> 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"
> {code}
> {{as_arrow_table()}} works fine.
> {code:r}
> 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"
> {code}
> 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]
>
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