ARROW-14199 [R] bindings for format (where possible)

[dragosmg]

No description provided.

[github-actions]

https://issues.apache.org/jira/browse/ARROW-14199

[github-actions]

⚠️ Ticket has not been started in JIRA, please click 'Start Progress'.

[dragosmg]

TL/DR:
In order to mimic the base R behaviour, if the timezone argument (tz) isn't specified, arrow::format() needs to extract it from the object (where possible). Only if that isn't possible, it should use the system timezone.

=================

I think the failures I am seeing so far are due to the difference between base::format() and base::strftime(). While in {arrow} they behave similarly (due to the nature of my implementation), in base R they do not:

library(dplyr, warn.conflicts = FALSE)
library(lubridate, warn.conflicts = FALSE)
times <- tibble(
  datetime = c(lubridate::ymd_hms("2018-10-07 19:04:05", tz = "Etc/GMT+6"), NA),
  date = c(as.Date("2021-01-01"), NA)
)
formats <- "%a %A %w %d %b %B %m %y %Y %H %I %p %M %z %Z %j %U %W %x %X %% %G %V %u"
a <- times$datetime[1]
a
#> [1] "2018-10-07 19:04:05 -06"
format(a, format = formats)
#> [1] "Sun Sunday 0 07 Oct October 10 18 2018 19 07 PM 04 -0600 -06 280 40 40 10/07/2018 19:04:05 % 2018 40 7"
strftime(a, format = formats)
#> [1] "Mon Monday 1 08 Oct October 10 18 2018 02 02 AM 04 +0100 BST 281 40 41 10/08/2018 02:04:05 % 2018 41 1"

^{Created on 2022-02-02 by the reprex package (v2.0.1)}

The difference boils down to:

# format()
format(as.POSIXlt(a), format = formats)
#> [1] "Sun Sunday 0 07 Oct October 10 18 2018 19 07 PM 04 -0600 -06 280 40 40 10/07/2018 19:04:05 % 2018 40 7"
# strftime()
format(as.POSIXlt(a, tz = ""), format = formats)
#> [1] "Mon Monday 1 08 Oct October 10 18 2018 02 02 AM 04 +0100 BST 281 40 41 10/08/2018 02:04:05 % 2018 41 1"

^{Created on 2022-02-02 by the reprex package (v2.0.1)}

[jonkeane]

Thanks for this! a few comments / suggestions at a high level

[paleolimbot]

The datetime bits are looking good! I added a few comments that may help to handle other types of objects that might get passed to format().

[dragosmg]

Follow-up ticket to remove / revisit the manual casting step - ARROW-15762.

[dragosmg]

@jonkeane I think this is ready for another pass if/when you have a bit of time

[jonkeane]

This is looking good — one super minor test addition and a question about build_expr() + clauses catching non-expressions

[jonkeane]

Almost there! One comment about a comment + a question about the tests

[jonkeane]

This is great, thanks for sticking through this.

[ursabot]

Benchmark runs are scheduled for baseline = 33fd1c2 and contender = dc2e0b2. dc2e0b2 is a master commit associated with this PR. Results will be available as each benchmark for each run completes.
Conbench compare runs links:
[Finished ⬇️0.0% ⬆️0.0%] ec2-t3-xlarge-us-east-2
[Finished ⬇️0.13% ⬆️0.0%] test-mac-arm
[Finished ⬇️0.0% ⬆️0.0%] ursa-i9-9960x
[Finished ⬇️0.13% ⬆️0.0%] ursa-thinkcentre-m75q
Supported benchmarks:
ec2-t3-xlarge-us-east-2: Supported benchmark langs: Python. Runs only benchmarks with cloud = True
test-mac-arm: Supported benchmark langs: C++, Python, R
ursa-i9-9960x: Supported benchmark langs: Python, R, JavaScript
ursa-thinkcentre-m75q: Supported benchmark langs: C++, Java