[jira] [Commented] (ARROW-15798) [R][C++] Discussion: Plans for date casting from int to support an origin option?

["Joris Van den Bossche (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/ARROW-15798?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17499592#comment-17499592 ] 

Joris Van den Bossche commented on ARROW-15798:
-----------------------------------------------

Pandas also has such an {{origin}} keyword in {{pd.to_datetime}} (I seem to remember that it can, for example, be useful for data coming from Matlab).

If we want to add something like this, I think we should add it as a separate kernel (to specifically convert integers/doubles to timestamp or date), and not add this to Cast.

> [R][C++] Discussion: Plans for date casting from int to support an origin option?
> ---------------------------------------------------------------------------------
>
>                 Key: ARROW-15798
>                 URL: https://issues.apache.org/jira/browse/ARROW-15798
>             Project: Apache Arrow
>          Issue Type: Improvement
>          Components: C++, R
>            Reporter: Dragoș Moldovan-Grünfeld
>            Priority: Major
>
> 2 questions:
> * plans to support an origin option for int -> date32 casting?
> * plans to support double -> date32 casting? 
> =======================
> Currently the casting from integer to date works, but assumes epoch (1970-01-01) as the origin. 
> {code:r}
> > a <- Array$create(32L)
> > a$cast(date32())
> Array
> <date32[day]>
> [
>   1970-02-02
> ]
> {code}
> Would it make sense to have an {{origin}} option that would allow the user to fine tune the casting? For example, in R the {{base::as.Date()}} function has such an argument
> {code:r}
> > as.Date(32, origin = "1970-01-02")
> [1] "1970-02-03"
> {code}
> We have a potential workaround in R (once we support date & duration arithmetic), but I was wondering if there might me more general interest for this. 
> A secondary aspect (as my R example shows) R support casting to date not only from integers, but also doubles. Would there be interesting in that? Need be I can split this into several tickets.  
> Are there any plans in either of these 2 directions?



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