Re: [I] [R] Empty character attributes not stored [arrow]

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

thisisnic commented on issue #29233:
URL: https://github.com/apache/arrow/issues/29233#issuecomment-4862714711

   Reproducible as of 24.0.0. A quick Claude analysis says:
   
   The bug is in [`array_to_vector.cpp:980`](https://github.com/apache/arrow/blob/3f4a04ee9fb40a5db78cb5257b88950599c1c11a/r/src/array_to_vector.cpp#L980):
   
   ```cpp
   std::string tzone = array_type->timezone();
   if (tzone.size() > 0) {
     data.attr("tzone") = tzone;
   }
   ```
   
   When the Arrow timestamp has no timezone (empty string), `tzone.size()` is 0, so the `tzone` attribute is never set on the R vector. But in R, `tzone = ""` is the default for `as.POSIXct()` and is meaningful (local timezone) — it's distinct from `tzone` being absent.
   
   The write path is correct: [`type_infer.cpp:78`](https://github.com/apache/arrow/blob/3f4a04ee9fb40a5db78cb5257b88950599c1c11a/r/src/type_infer.cpp#L78) passes the empty string through to `timestamp()`. The fix would be to always set the attribute, removing the `if` guard.


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