[jira] [Created] (ARROW-14124) [R] Timezone support in R <= 3.4

["Jonathan Keane (Jira)" <ji...@apache.org>]

Jonathan Keane created ARROW-14124:
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             Summary: [R] Timezone support in R <= 3.4
                 Key: ARROW-14124
                 URL: https://issues.apache.org/jira/browse/ARROW-14124
             Project: Apache Arrow
          Issue Type: Bug
          Components: R
            Reporter: Jonathan Keane
            Assignee: Jonathan Keane


The error is: https://github.com/ursacomputing/crossbow/runs/3696604088#step:7:15209

{code}
 Timezone not present, cannot convert to string with timezone: %Y-%m-%d%z
{code}

Ok, I think I’ve got close to the source of the issue (though let me tell you neither the source nor the docs for R are accurate [1] on this…)

3.4 (and earlier):
{code:r}
> attributes(c(lubridate::ymd_hms("2018-10-07 19:04:05", tz = "Etc/GMT+6"), NA)) 
$class
[1] "POSIXct" "POSIXt" 
{code}

3.5 (and later):
{code:r}
> attributes(c(lubridate::ymd_hms("2018-10-07 19:04:05", tz = "Etc/GMT+6"), NA)) 
$class
[1] "POSIXct" "POSIXt" 

$tzone
[1] "Etc/GMT+6"
{code}

So R itself is dropping the {{tzone}} attribute when we use {{c()}}, that is being passed to Arrow as such, and then when Arrow goes to print a timezone it (rightfully!) complains that there is no timezone to be formatted into the string. 

This behavior actually sounds right (given the inputs), so I propose that we catch the error R <=3.4 (or skip the test in r<=3.4)

[1] - The documented behavior is current, but it didn't change at the same time as the actual behavior.

The docs starting in 4.1.0 state:
 Using \code{\link{c}} on \code{"POSIXlt"} objects converts them to the
  current time zone, and on \code{"POSIXct"} objects drops any
  \code{"tzone"} attributes, unless they are all marked with the same
  time zone.
https://github.com/wch/r-source/blob/tags/R-4-1-0/src/library/base/man/DateTimeClasses.Rd#L180-L183

The docs before that state:
  Using \code{\link{c}} on \code{"POSIXlt"} objects converts them to the
  current time zone, and on \code{"POSIXct"} objects drops any
  \code{"tzone"} attributes (even if they are all marked with the same
  time zone).
https://github.com/wch/r-source/blob/tags/R-4-0-5/src/library/base/man/DateTimeClasses.Rd




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