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https://issues.apache.org/jira/browse/ARROW-15862?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17560958#comment-17560958
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Antoine Pitrou commented on ARROW-15862:
----------------------------------------
Well, if the cast would truncate, it fails by default but you can select an
unsafe cast:
{code:python}
>>> pc.cast(3.5, pa.int64())
Traceback (most recent call last):
...
ArrowInvalid: Float value 3.5 was truncated converting to int64
>>> pc.cast(3.5, pa.int64(), safe=False)
<pyarrow.Int64Scalar: 3>
{code}
> [C++] Provide a way to go from numeric to duration
> --------------------------------------------------
>
> Key: ARROW-15862
> URL: https://issues.apache.org/jira/browse/ARROW-15862
> Project: Apache Arrow
> Issue Type: Improvement
> Components: C++
> Reporter: Dragoș Moldovan-Grünfeld
> Priority: Critical
>
> *Update*: I keep forgetting that R integers are translated into int32 (since
> R does not have int64). int64 -> duration is supported.
> Would it make sense to support float -> duration or int32 -> duration?
> ======================
> Currently it is not possible to directly create a duration object from a
> numeric one (for example through casting).
> {code:r}
> library(arrow)
> a <- Array$create(32L)
> a$cast(duration("s"))
> #> Error: NotImplemented: Unsupported cast from int32 to duration using
> function cast_duration
> #> /Users/dragos/Documents/arrow/cpp/src/arrow/compute/function.cc:231
> DispatchBest(&inputs)
> {code}
> This underpins a lot of the date-time arithmetic in R, which support the
> conversion/ coercion of an integer to difftime (R's equivalent for duration),
> such as in the pipeline below.
> {code:r}
> library(arrow, warn.conflicts = FALSE)
> #> See arrow_info() for available features
> library(dplyr, warn.conflicts = FALSE)
> library(lubridate, warn.conflicts = FALSE)
> df <- tibble(time = as_datetime(c("2022-03-07 15:00:28", "2022-03-06
> 14:00:28")))
> df
> #> # A tibble: 2 × 1
> #> time
> #> <dttm>
> #> 1 2022-03-07 15:00:28
> #> 2 2022-03-06 14:00:28
> df %>%
> mutate(time2 = time + seconds(2))
> #> # A tibble: 2 × 2
> #> time time2
> #> <dttm> <dttm>
> #> 1 2022-03-07 15:00:28 2022-03-07 15:00:30
> #> 2 2022-03-06 14:00:28 2022-03-06 14:00:30
> {code}
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