[ARROW-15862] [C++] Provide a way to go from numeric to duration

• Type: Improvement
• Status: Open
• Priority: Critical
• Resolution: Unresolved
• Component/s: C++
• External issue URL: https://github.com/apache/arrow/issues/31298
• Assignee: Unassigned
• Reporter: Dragoș Moldovan-Grünfeld
• Created: 07/Mar/22 16:29
• Updated: 11/Jan/23 11:40

Description

Update: I keep forgetting that R integers are translated into int32 (since R does not have int64). int64 -> duration is supported. 
 Would it make sense to support float -> duration or int32 -> duration?

======================
Currently it is not possible to directly create a duration object from a numeric one (for example through casting).

library(arrow)

a <- Array$create(32L)
a$cast(duration("s"))
#> Error: NotImplemented: Unsupported cast from int32 to duration using function cast_duration
#> /Users/dragos/Documents/arrow/cpp/src/arrow/compute/function.cc:231  DispatchBest(&inputs)

This underpins a lot of the date-time arithmetic in R, which support the conversion/ coercion of an integer to difftime (R's equivalent for duration), such as in the pipeline below.

library(arrow, warn.conflicts = FALSE)
#> See arrow_info() for available features
library(dplyr, warn.conflicts = FALSE)
library(lubridate, warn.conflicts = FALSE)

df <- tibble(time = as_datetime(c("2022-03-07 15:00:28", "2022-03-06 14:00:28"))) 
df
#> # A tibble: 2 × 1
#>   time               
#>   <dttm>             
#> 1 2022-03-07 15:00:28
#> 2 2022-03-06 14:00:28

df %>% 
  mutate(time2 = time + seconds(2))
#> # A tibble: 2 × 2
#>   time                time2              
#>   <dttm>              <dttm>             
#> 1 2022-03-07 15:00:28 2022-03-07 15:00:30
#> 2 2022-03-06 14:00:28 2022-03-06 14:00:30

Issue Links

• is duplicated by: ARROW-17044 [C++] Cast to duration from types other than int64
• relates to: ARROW-16253 [R] Helper function for casting from float to duration via int64()
• supercedes: ARROW-15858 [C++][R] Can't cast integer difftime to duration (but works with double)