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

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

    [ https://issues.apache.org/jira/browse/ARROW-13588?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17421380#comment-17421380 ] 

Neal Richardson commented on ARROW-13588:
-----------------------------------------

Will resolve in ARROW-12871

> [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
>            Assignee: Neal Richardson
>            Priority: Critical
>              Labels: attributes, feather
>             Fix For: 6.0.0
>
>
> 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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