[ARROW-18337] [R] Possible undesirable handling of POSIXlt objects

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 11.0.0
• Component/s: R
• Labels: pull-request-available
• External issue URL: https://github.com/apache/arrow/issues/33506
• Assignee: Dewey Dunnington
• Reporter: Danielle Navarro
• Created: 16/Nov/22 06:08
• Updated: 11/Jan/23 13:20
• Resolved: 11/Jan/23 13:20

Description

In the course of updating documentation, I noticed that it is possible to create an Arrow array of POSIXlt objects from R, but not a scalar.

https://github.com/apache/arrow/pull/14514#discussion_r1016078081

This works:

tm <- as.POSIXlt(c(Sys.time(), Sys.time()))
arrow::Array$create(tm)

This fails:

arrow::Scalar$create(as.POSIXlt(Sys.time()))

It's possible to manually convert a POSIXlt object to a struct scalar like this:

df <- as.data.frame(unclass(as.POSIXlt(Sys.time())))
arrow::Scalar$create(df, 
              type = struct(
                sec = float32(), 
                min = int32(),
                hour = int32(),
                mday = int32(),
                mon = int32(),
                year = int32(),
                wday = int32(),
                yday = int32(),
                isdst = int32(),
                zone = utf8(),
                gmtoff = int32()
              ))

although this does not seem precisely the same as the behaviour of Array$create() which creates an extension type?

It was unclear to us (thisisnic and myself) whether the current behaviour was desirable, so it seemed sensible to open an issue!

Related issue:

https://issues.apache.org/jira/browse/ARROW-18263

Issue Links

• links to: GitHub Pull Request #15277