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https://issues.apache.org/jira/browse/ARROW-14200?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17423428#comment-17423428
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Jonathan Keane commented on ARROW-14200:
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Thanks for digging (I hadn't had a chance to yet), I've changed the tags
> [R] 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: Bug
> Components: R
> Reporter: Jonathan Keane
> Priority: Major
>
> 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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