[jira] [Assigned] (ARROW-13588) [R] Empty character attributes not stored

["Todd Farmer (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/ARROW-13588?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Todd Farmer reassigned ARROW-13588:
-----------------------------------

    Assignee:     (was: Neal Richardson)

This issue was last updated over 90 days ago, which may be an indication it is no longer being actively worked. To better reflect the current state, the issue is being unassigned. Please feel free to re-take assignment of the issue if it is being actively worked, or if you plan to start that work soon.

> [R] Empty character attributes not stored
> -----------------------------------------
>
>                 Key: ARROW-13588
>                 URL: https://issues.apache.org/jira/browse/ARROW-13588
>             Project: Apache Arrow
>          Issue Type: Bug
>          Components: R
>    Affects Versions: 5.0.0
>         Environment: Ubuntu 20.04 R 4.1 release
>            Reporter: Charlie Gao
>            Priority: Critical
>              Labels: attributes, feather
>
> Date-times in the POSIXct format have a 'tzone' attribute that by default is set to "", an empty character vector (not NULL) when created.
> This however is not stored in the Arrow feather file. When the file is read back, the original and restored dataframes are not identical as per the below reprex.
> I am thinking that this should not be the intention? My workaround at the moment is making a check when reading back to write the empty string if the tzone attribute does not exist.
> Just to confirm, the attribute is stored correctly when it is not empty.
> Thanks.
> {code:java}
> ``` r
>  dates <- as.POSIXct(c("2020-01-01", "2020-01-02", "2020-01-02"))
>  attributes(dates)
>  #> $class
>  #> [1] "POSIXct" "POSIXt" 
>  #> 
>  #> $tzone
>  #> [1] ""
>  values <- c(1:3)
>  original <- data.frame(dates, values)
>  original
>  #> dates values
>  #> 1 2020-01-01 1
>  #> 2 2020-01-02 2
>  #> 3 2020-01-02 3
> tempfile <- tempfile()
> arrow::write_feather(original, tempfile)
> restored <- arrow::read_feather(tempfile)
> identical(original, restored)
>  #> [1] FALSE
>  waldo::compare(original, restored)
>  #> `attr(old$dates, 'tzone')` is a character vector ('')
>  #> `attr(new$dates, 'tzone')` is absent
> unlink(tempfile)
>  ```
> {code}
>  



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