[
https://issues.apache.org/jira/browse/ARROW-15858?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17511742#comment-17511742
]
Dragoș Moldovan-Grünfeld commented on ARROW-15858:
--------------------------------------------------
We can go via {{{}int64(){}}}, so not sure how to/ if we need to make this more
robust.
{code:r}
library(arrow, warn.conflicts = FALSE)
a <- as.difftime(32L, units = "secs")
a
#> Time difference of 32 secs
Array$create(a)
#> Array
#> <int32>
#> [
#> 32
#> ]
Array$create(a, type = int64())$cast(duration("s"))
#> Array
#> <duration[s]>
#> [
#> 32
#> ]
{code}
> [C++][R] Can't cast integer difftime to duration (but works with double)
> ------------------------------------------------------------------------
>
> Key: ARROW-15858
> URL: https://issues.apache.org/jira/browse/ARROW-15858
> Project: Apache Arrow
> Issue Type: Bug
> Components: C++, R
> Reporter: Dragoș Moldovan-Grünfeld
> Priority: Critical
>
> It's possible to cast doubles to durations, but not integers. This has been
> found in the R code via the issues below:
> The shortest reprex I can make is as follows:
> {code:r}
> # Successfully cast a double to a duration
> vec_to_Array(as.difftime(32, units = "secs"), NULL)$cast(duration())
> #> Array
> #> <duration[s]>
> #> [
> #> 32
> #> ]
> # Fail to do so with an integer
> vec_to_Array(as.difftime(32L, units = "secs"), NULL)$cast(duration())
> #> Error: NotImplemented: Unsupported cast from int32 to duration using
> function cast_duration
> {code}
> ----------------------------------------------------------------------------
> I would expect both {{a}} and {{b}} to create a {{duration}} object of 32
> seconds, but the second one returns an {{int32}}
> {code:r}
> library(arrow, warn.conflicts = FALSE)
> a <- as.difftime(32, units = "secs") # i.e. a double
> b <- as.difftime(32L, units = "secs") # i.e. an integer
> Array$create(a)
> #> Array
> #> <duration[s]>
> #> [
> #> 32
> #> ]
> Array$create(b)
> #> Array
> #> <int32>
> #> [
> #> 32
> #> ]
> {code}
> If I try to be explicit, I get somewhat of a clue why that might be happening:
> {code:r}
>
> Array$create(a, type = duration())
> #> Array
> #> <duration[s]>
> #> [
> #> 32
> #> ]
> Array$create(b, type = duration())
> #> Error:
> #> ! NotImplemented: Extend
> {code}
> Nevertheless, the fallback to creating an integer was unexpected.
--
This message was sent by Atlassian Jira
(v8.20.1#820001)
