[jira] [Created] (ARROW-16316) How to round the timestamps in a mutate statement?

["Zsolt Kegyes-Brassai (Jira)" <ji...@apache.org>]

Zsolt Kegyes-Brassai created ARROW-16316:
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             Summary: How to round the timestamps in a mutate statement?
                 Key: ARROW-16316
                 URL: https://issues.apache.org/jira/browse/ARROW-16316
             Project: Apache Arrow
          Issue Type: Wish
    Affects Versions: 7.0.0
            Reporter: Zsolt Kegyes-Brassai


I was trying to aggregate over time using different granularity. Usually I would use the {{lubridate::floor_date()}} , which is currently not supported for parquet datasets.


Is there any comprehensive list of supported list of currently supported {{lubridate }}(or {{{}dplyr{}}}) verbs? Maybe, it’s only my fault, but except the changelog I haven’t find any relevant information.

 

Later I found that the {{round_temporal()}} function is exposed to {{{}R{}}}. 
But I am struggling to find the right syntax inside a mutate statement to apply on a {{timestamp[us, tz=UTC]}} type column.
{code:java}
new_dataset |>
  mutate(time = arrow_round_temporal(time))
#>  Error: Invalid: Attempted to initialize KernelState from null FunctionOptions
{code}
 

 

Here are some other attempts:
{code:java}
library(arrow)

arrow_now <- Scalar$create(lubridate::now())
(arrow_now)
#> Scalar
#> 2022-04-25 11:44:33.805609
call_function("round_temporal", arrow_now)
#> Scalar
#> 2022-04-25 00:00:00.000000
call_function("round_temporal", arrow_now, unit = "day")
#> Error: Argument 2 is of class character but it must be one of "Array", "ChunkedArray", "RecordBatch", "Table", or "Scalar"
arrow_unit <- Scalar$create("day")
(arrow_unit)
#> Scalar
#> day
call_function("round_temporal", arrow_now, unit = arrow_unit)
#> Error: Invalid: Function 'round_temporal' accepts 1 arguments but attempted to look up kernel(s) with 2
{code}
 



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