[jira] [Commented] (ARROW-17143) [R] Add examples working with `tidyr::unnest`and `tidyr::unnest_longer`

["Neal Richardson (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/ARROW-17143?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17569015#comment-17569015 ] 

Neal Richardson commented on ARROW-17143:
-----------------------------------------

These tidyr functions aren't working on Arrow Tables, they're working on the R data.frame that read_json_arrow returns. I guess you could add something about this to the cookbook, but there's no real connection to anything in the package itself.

> [R] Add examples working with `tidyr::unnest`and `tidyr::unnest_longer`
> -----------------------------------------------------------------------
>
>                 Key: ARROW-17143
>                 URL: https://issues.apache.org/jira/browse/ARROW-17143
>             Project: Apache Arrow
>          Issue Type: Improvement
>          Components: Documentation, R
>    Affects Versions: 8.0.1
>            Reporter: SHIMA Tatsuya
>            Priority: Major
>
> Related to ARROW-8813 ARROW-12099
> The arrow package can convert json files to data frames very easily, but {{tidyr::unnest_longer}} is needed for array expansion.
> Wonder if {{tidyr}} could be added to the recommended package and examples like this could be included in the documentation and test cases.
> {code:r}
> tf <- tempfile()
> on.exit(unlink(tf))
> writeLines('
>     { "hello": 3.5, "world": false, "foo": { "bar": [ 1, 2 ] } }
>     { "hello": 3.25, "world": null }
>     { "hello": 0.0, "world": true, "foo": { "bar": [ 3, 4, 5 ] } }
>   ', tf)
> arrow::read_json_arrow(tf) |>
>   tidyr::unnest(foo, names_sep = ".") |>
>   tidyr::unnest_longer(foo.bar)
> #> # A tibble: 6 × 3
> #>   hello world foo.bar
> #>   <dbl> <lgl>   <int>
> #> 1  3.5  FALSE       1
> #> 2  3.5  FALSE       2
> #> 3  3.25 NA         NA
> #> 4  0    TRUE        3
> #> 5  0    TRUE        4
> #> 6  0    TRUE        5
> {code}



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