[
https://issues.apache.org/jira/browse/ARROW-13938?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17415686#comment-17415686
]
Joris Van den Bossche commented on ARROW-13938:
-----------------------------------------------
>From my experience with pandas, fully agreed that autocasting strings as
>timestamps in operations is a very nice convenience.
And I think there are arguments for having timestamp be an exception here (as
we indeed should not autocast to integers or floats), since you don't have a
"native" scalar object like you have for ints, floats and strings, i.e. you
need to create an object (eg calling {{datetime.datetime()}},
{{datetime.datetime.strptime()}} or {{pd.Timestamp()}} in Python). (although
now writing this, the same could maybe be said for decimals ..)
I am only wondering a bit at what level this casting should be implemented. It
might also be possible to let this be a responsibility of "user API" level
(i.e. part of the R / Python bindings)? Or would that be difficult to implement
at that level?
> [C++] Date and datetime types should autocast from strings
> ----------------------------------------------------------
>
> Key: ARROW-13938
> URL: https://issues.apache.org/jira/browse/ARROW-13938
> Project: Apache Arrow
> Issue Type: Improvement
> Components: C++
> Reporter: Jonathan Keane
> Priority: Major
>
> When comparing dates and datetimes, people frequently expect that a string
> (formatted as ISO8601) will auto-cast and compare to dates and times.
> Examples in R:
> {code:r}
> library(arrow)
> #>
> #> Attaching package: 'arrow'
> #> The following object is masked from 'package:utils':
> #>
> #> timestamp
> arr <- Array$create(as.Date(c("1974-04-06", "1988-05-09")))
> arr > "1980-01-01"
> #> Error: NotImplemented: Function greater has no kernel matching input types
> (array[date32[day]], scalar[string])
> # creating the scalar as a date works, of course
> arr > Scalar$create(as.Date("1980-01-01"))
> #> Array
> #> <bool>
> #> [
> #> false,
> #> true
> #> ]
> # datatimes also do not auto-cast
> arr <- Array$create(Sys.time())
> arr > "1980-01-01 00:00:00"
> #> Error: NotImplemented: Function greater has no kernel matching input types
> (array[timestamp[us]], scalar[string])
> # or a more real-world example
> library(dplyr)
> #>
> #> Attaching package: 'dplyr'
> #> The following objects are masked from 'package:stats':
> #>
> #> filter, lag
> #> The following objects are masked from 'package:base':
> #>
> #> intersect, setdiff, setequal, union
> mtcars$date <- as.Date(c("1974-04-06", "1988-05-09"))
> ds <- InMemoryDataset$create(mtcars)
> ds %>%
> filter(date > "1980-01-01") %>%
> collect()
> #> Error: NotImplemented: Function greater has no kernel matching input types
> (array[date32[day]], scalar[string])
> {code}
--
This message was sent by Atlassian Jira
(v8.3.4#803005)
