[I] [R] How to convert the timestamp without time zone type to the POSIXct type ideally? [arrow]

["eitsupi (via GitHub)" <gi...@apache.org>]

eitsupi opened a new issue, #40309:
URL: https://github.com/apache/arrow/issues/40309

   ### Describe the bug, including details regarding any error messages, version, and platform.
   
   The POSIXct type in R seems to behave in the absence of time zone information in such a way that it is interpreted as the time zone time in which the R session is running.
   
   However, the arrow package does not consider the time zone of the R session when converting from the Arrow timestamp type to the POSIXct type.
   
   ``` r
   library(arrow)
   #>
   #> Attaching package: 'arrow'
   #> The following object is masked from 'package:utils':
   #>
   #>     timestamp
   
   Sys.setenv(TZ = "UTC")
   
   x <- "1900-01-01"
   a_a <- chunked_array(as.POSIXct(x), type = timestamp())
   a_a
   #> ChunkedArray
   #> <timestamp[s]>
   #> [
   #>   [
   #>     1900-01-01 00:00:00
   #>   ]
   #> ]
   
   out <- as.vector(a_a)
   
   as.POSIXct(x)
   #> [1] "1900-01-01 UTC"
   unclass(as.POSIXct(x))
   #> [1] -2208988800
   #> attr(,"tzone")
   #> [1] ""
   out
   #> [1] "1900-01-01 UTC"
   unclass(out)
   #> [1] -2208988800
   
   Sys.setenv(TZ = "Europe/Paris")
   
   as.POSIXct(x)
   #> [1] "1900-01-01 PMT"
   unclass(as.POSIXct(x))
   #> [1] -2208989361
   #> attr(,"tzone")
   #> [1] ""
   out
   #> [1] "1900-01-01 00:09:21 PMT"
   unclass(out)
   #> [1] -2208988800
   ```
   
   <sup>Created on 2024-03-01 with [reprex v2.0.2](https://reprex.tidyverse.org)</sup>
   
   Is there a reason why this behavior was chosen? Or is this a bug and should be fixed? (which is, of course, a breaking change).
   
   I found this behavior in this issue (pola-rs/r-polars#875)
   
   ### Component(s)
   
   R


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