jonkeane commented on a change in pull request #12240:
URL: https://github.com/apache/arrow/pull/12240#discussion_r791779372
##########
File path: r/tests/testthat/test-Array.R
##########
@@ -985,3 +985,14 @@ test_that("Array to C-interface", {
delete_arrow_schema(schema_ptr)
delete_arrow_array(array_ptr)
})
+
+test_that("Array coverts timestamps with missing timezone /assumed local tz
correctly", {
+ withr::with_envvar(c(TZ = "America/Chicago"), {
+ a <- as.POSIXct("1970-01-01 00:00:00")
+ attr(a, "tzone") <- Sys.getenv("TZ")
Review comment:
The phrase "the display" here is confusing / wrong in some
circumstances. When printing arrays, currently AFAICT arrow prints the
timestamp in UTC for datetimes regardless if there is a timezone attached or
not:
``` r
library(arrow, warn.conflicts = FALSE)
# specifically setting the timezone, and the Arrow Array repl shows UTC
ts <- as.POSIXct("2020-01-01 02:00:00", tz = "America/Chicago") + 1:10*3600
ts
#> [1] "2020-01-01 03:00:00 CST" "2020-01-01 04:00:00 CST"
#> [3] "2020-01-01 05:00:00 CST" "2020-01-01 06:00:00 CST"
#> [5] "2020-01-01 07:00:00 CST" "2020-01-01 08:00:00 CST"
#> [7] "2020-01-01 09:00:00 CST" "2020-01-01 10:00:00 CST"
#> [9] "2020-01-01 11:00:00 CST" "2020-01-01 12:00:00 CST"
attr(ts, "tzone")
#> [1] "America/Chicago"
arr <- Array$create(ts)
arr
#> Array
#> <timestamp[us, tz=America/Chicago]>
#> [
#> 2020-01-01 09:00:00.000000,
#> 2020-01-01 10:00:00.000000,
#> 2020-01-01 11:00:00.000000,
#> 2020-01-01 12:00:00.000000,
#> 2020-01-01 13:00:00.000000,
#> 2020-01-01 14:00:00.000000,
#> 2020-01-01 15:00:00.000000,
#> 2020-01-01 16:00:00.000000,
#> 2020-01-01 17:00:00.000000,
#> 2020-01-01 18:00:00.000000
#> ]
arr$type$timezone()
#> [1] "America/Chicago"
as.vector(arr)
#> [1] "2020-01-01 03:00:00 CST" "2020-01-01 04:00:00 CST"
#> [3] "2020-01-01 05:00:00 CST" "2020-01-01 06:00:00 CST"
#> [5] "2020-01-01 07:00:00 CST" "2020-01-01 08:00:00 CST"
#> [7] "2020-01-01 09:00:00 CST" "2020-01-01 10:00:00 CST"
#> [9] "2020-01-01 11:00:00 CST" "2020-01-01 12:00:00 CST"
attr(as.vector(arr), "tzone")
#> [1] "America/Chicago"
# without setting the timezone, and the Arrow Array repl still shows UTC
ts <- as.POSIXct("2020-01-01 02:00:00") + 1:10*3600
ts
#> [1] "2020-01-01 03:00:00 CST" "2020-01-01 04:00:00 CST"
#> [3] "2020-01-01 05:00:00 CST" "2020-01-01 06:00:00 CST"
#> [5] "2020-01-01 07:00:00 CST" "2020-01-01 08:00:00 CST"
#> [7] "2020-01-01 09:00:00 CST" "2020-01-01 10:00:00 CST"
#> [9] "2020-01-01 11:00:00 CST" "2020-01-01 12:00:00 CST"
attr(ts[[1]], "tzone")
#> NULL
arr <- Array$create(ts)
arr
#> Array
#> <timestamp[us]>
#> [
#> 2020-01-01 09:00:00.000000,
#> 2020-01-01 10:00:00.000000,
#> 2020-01-01 11:00:00.000000,
#> 2020-01-01 12:00:00.000000,
#> 2020-01-01 13:00:00.000000,
#> 2020-01-01 14:00:00.000000,
#> 2020-01-01 15:00:00.000000,
#> 2020-01-01 16:00:00.000000,
#> 2020-01-01 17:00:00.000000,
#> 2020-01-01 18:00:00.000000
#> ]
arr$type$timezone()
#> [1] ""
as.vector(arr)
#> [1] "2020-01-01 03:00:00 CST" "2020-01-01 04:00:00 CST"
#> [3] "2020-01-01 05:00:00 CST" "2020-01-01 06:00:00 CST"
#> [5] "2020-01-01 07:00:00 CST" "2020-01-01 08:00:00 CST"
#> [7] "2020-01-01 09:00:00 CST" "2020-01-01 10:00:00 CST"
#> [9] "2020-01-01 11:00:00 CST" "2020-01-01 12:00:00 CST"
attr(as.vector(arr), "tzone")
#> NULL
```
But as I showed up there, when pulling the data back in with
`as.vector(arr)`, the timezone is pulled in with it so that when R displays the
timestamp it is faithful to the original timestamp.
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