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https://issues.apache.org/jira/browse/ARROW-15919?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17505045#comment-17505045
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Dragoș Moldovan-Grünfeld commented on ARROW-15919:
--------------------------------------------------
As a general remark: Would it make sense for some of the operations involving
durations to work with scalars? For example 2 * duration -> duration. Extending
the example in description:
{code:r}
> b_array * 2L
Error: NotImplemented: Function 'multiply_checked' has no kernel matching
input types (array[duration[s]], scalar[int32])
/Users/dragos/Documents/arrow/cpp/src/arrow/compute/function.cc:231
DispatchBest(&inputs)
> 2L * b_array
Error: NotImplemented: Function 'multiply_checked' has no kernel matching
input types (scalar[int32], array[duration[s]])
/Users/dragos/Documents/arrow/cpp/src/arrow/compute/function.cc:231
DispatchBest(&inputs)
{code}
> [C++] Add_kernel not commutative (timestamps & duration maths)
> --------------------------------------------------------------
>
> Key: ARROW-15919
> URL: https://issues.apache.org/jira/browse/ARROW-15919
> Project: Apache Arrow
> Issue Type: Sub-task
> Components: C++
> Reporter: Dragoș Moldovan-Grünfeld
> Assignee: Rok Mihevc
> Priority: Blocker
>
> A + B != B + A when it comes to adding duration to timestamp, for example.
> Should {{add(timestamp, duration) == add(duration, timestamp)}}? Or, in other
> words, should the order matter?
> This has surfaced in R when creating some of the lubridate bindings - see
> non-lubridate example below
> {code:r}
> a <- ymd("2009-08-03", tz = "America/Chicago")
> a_array <- Array$create(rep(a, 12))
> b_array <- Array$create((1:12)*86400L)$cast(time32(unit = "s")) -
> Array$create(rep(0L, 12))$cast(time32(unit = "s"))
> a_array
> a_array
> Array
> <timestamp[us, tz=America/Chicago]>
> [
> 2009-08-03 05:00:00.000000,
> 2009-08-03 05:00:00.000000,
> 2009-08-03 05:00:00.000000,
> 2009-08-03 05:00:00.000000,
> 2009-08-03 05:00:00.000000,
> 2009-08-03 05:00:00.000000,
> 2009-08-03 05:00:00.000000,
> 2009-08-03 05:00:00.000000,
> 2009-08-03 05:00:00.000000,
> 2009-08-03 05:00:00.000000,
> 2009-08-03 05:00:00.000000,
> 2009-08-03 05:00:00.000000
> ]
> b_array
> Array
> <duration[s]>
> [
> 86400,
> 172800,
> 259200,
> 345600,
> 432000,
> 518400,
> 604800,
> 691200,
> 777600,
> 864000,
> 950400,
> 1036800
> ]
> a_array + b_array
> Array
> <timestamp[us, tz=America/Chicago]>
> [
> 2009-08-04 05:00:00.000000,
> 2009-08-05 05:00:00.000000,
> 2009-08-06 05:00:00.000000,
> 2009-08-07 05:00:00.000000,
> 2009-08-08 05:00:00.000000,
> 2009-08-09 05:00:00.000000,
> 2009-08-10 05:00:00.000000,
> 2009-08-11 05:00:00.000000,
> 2009-08-12 05:00:00.000000,
> 2009-08-13 05:00:00.000000,
> 2009-08-14 05:00:00.000000,
> 2009-08-15 05:00:00.000000
> ]
> b_array + a_array
> Error: NotImplemented: Function 'add_checked' has no kernel matching input
> types (array[duration[us]], array[timestamp[us, tz=America/Chicago]])
> /Users/dragos/Documents/arrow/cpp/src/arrow/compute/function.cc:231
> DispatchBest(&inputs)
> {code}
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