[jira] [Commented] (ARROW-14051) [R] Handle conditionals enclosing aggregate expressions

["Dewey Dunnington (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/ARROW-14051?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17438009#comment-17438009 ] 

Dewey Dunnington commented on ARROW-14051:
------------------------------------------

The (partial) stack trace generating the error is this:

`Expression$type_id()`: [https://github.com/apache/arrow/blob/master/r/R/expression.R#L140]

`nse_funcs$is.factor()`: [https://github.com/apache/arrow/blob/master/r/R/dplyr-functions.R#L229]

`nse_funcs$if_else()`: [https://github.com/apache/arrow/blob/master/r/R/dplyr-functions.R#L895]

 

It looks like the `Expression` that gets created has the `$schema` field dropped in `make_field_refs()` (hence the `NULL` schema) that triggers the error: [https://github.com/apache/arrow/blob/master/r/R/dplyr-summarize.R#L222]

> [R] Handle conditionals enclosing aggregate expressions
> -------------------------------------------------------
>
>                 Key: ARROW-14051
>                 URL: https://issues.apache.org/jira/browse/ARROW-14051
>             Project: Apache Arrow
>          Issue Type: Improvement
>          Components: R
>            Reporter: Ian Cook
>            Assignee: Dewey Dunnington
>            Priority: Major
>              Labels: query-engine
>
> This type of {{summarise()}} expression does not work in arrow:
> {code:r}
> Table$create(x = c(0, 1, 1), y = c(2, 3, 5), z = c(8, 13, 21)) %>%
>   group_by(x) %>%
>   summarise(r = ifelse(n() > 1, mean(y), mean(z))){code}



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