Jonathan Keane created ARROW-14200:
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Summary: [R] [C++] strftime on a date should not use or be
confused by timezones
Key: ARROW-14200
URL: https://issues.apache.org/jira/browse/ARROW-14200
Project: Apache Arrow
Issue Type: New Feature
Components: C++, R
Reporter: Jonathan Keane
When the input to {{strftime}} is a date, timezones shouldn't be necessary or
assumed.
What I think is going on below is the date 1992-01-01 is being interpreted as
1992-01-01 00:00:00 in UTC, and then when {{strftime()}} is being called it's
displaying that timestamp as 1991-12-31 ... (since my system is set to an after
UTC timezone), and then taking the year out of it. If I specify {{tz = "utc"}}
in the {{strftime()}}, I get the expected result (though that shouldn't be
necessary).
Run in the US central timezone:
{code}
library(arrow, warn.conflicts = FALSE)
library(dplyr, warn.conflicts = FALSE)
library(lubridate, warn.conflicts = FALSE)
Table$create(
data.frame(
x = as.Date("1992-01-01")
)
) %>%
mutate(
as_int_strftime = as.integer(strftime(x, "%Y")),
strftime = strftime(x, "%Y"),
as_int_strftime_utc = as.integer(strftime(x, "%Y", tz = "UTC")),
strftime_utc = strftime(x, "%Y", tz = "UTC"),
year = year(x)
) %>%
collect()
#> x as_int_strftime strftime as_int_strftime_utc strftime_utc year
#> 1 1992-01-01 1991 1991 1992 1992 1992
{code}
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