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https://issues.apache.org/jira/browse/ARROW-15996?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17511259#comment-17511259
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Joris Van den Bossche edited comment on ARROW-15996 at 3/23/22, 1:29 PM:
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You don't necessarily have to do the division yourself, as we can casting
durations from one unit to the other is supported (and will take care of
rounding / erroring if data is lost):
{code}
In [15]: pa.array([1000000, 2000000],
pa.time64('us')).cast(pa.int64()).cast(pa.duration('us')).cast(pa.duration('s'))
Out[15]:
<pyarrow.lib.DurationArray object at 0x7fc37dca76a0>
[
1,
2
]
{code}
The same will be true if you get the duration by subtracting two times, as that
will also not necessarily result in a second resolution duration.
was (Author: jorisvandenbossche):
You don't necessarily have to do the division yourself, as we can casting
durations from one unit to the other is supported (and will take care of
rounding / erroring if data is lost):
{code}
In [15]: pa.array([1000000, 2000000],
pa.time64('us')).cast(pa.int64()).cast(pa.duration('us')).cast(pa.duration('s'))
Out[15]:
<pyarrow.lib.DurationArray object at 0x7fc37dca76a0>
[
1,
2
]
{code}
> [C++] Support casting from time32 and time64 to duration
> --------------------------------------------------------
>
> Key: ARROW-15996
> URL: https://issues.apache.org/jira/browse/ARROW-15996
> Project: Apache Arrow
> Issue Type: Improvement
> Components: C++
> Reporter: Dragoș Moldovan-Grünfeld
> Priority: Critical
>
> It would be really helpful if we could convert {{time32}} and {{time64}} to
> {{duration}}. For example, it could simplify the implementation of some of
> the R bindings (e.g. {{difftime}}).
> {code:r}
> library(arrow, warn.conflicts = FALSE)
> a <- Array$create(32000L)
> a
> #> Array
> #> <int32>
> #> [
> #> 32000
> #> ]
> a$cast(time32())
> #> Array
> #> <time32[ms]>
> #> [
> #> 00:00:32.000
> #> ]
> a$cast(int64())$cast(time64())
> #> Array
> #> <time64[ns]>
> #> [
> #> 00:00:00.000032000
> #> ]
> a$cast(time32())$cast(duration())
> #> Error: NotImplemented: Unsupported cast from time32[ms] to duration using
> function cast_duration
> a$cast(int64())$cast(time64())$cast(duration())
> #> Error: NotImplemented: Unsupported cast from time64[ns] to duration using
> function cast_duration
> {code}
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