Should time zones be changing datetime formatting?

[jameslairdsmith]

It seems like (not) specifying a time zone makes datetime columns print differently?

library(tibble)
chr_date <- "05/04/23 19:22:21"

tibble(a = as.POSIXct(chr_date, "%d/%m/%y %H:%M:%S", tz = "UTC"),
       b = as.POSIXct(chr_date, "%d/%m/%y %H:%M:%S"))
#> # A tibble: 1 × 2
#>   a                   b               
#>   <dttm>              <dttm>          
#> 1 2023-04-05 19:22:21 5-04-23 19:22:21

^{Created on 2023-04-05 by the reprex package (v2.0.1)}

Session info

sessioninfo::session_info()
#> ─ Session info ───────────────────────────────────────────────────────────────
#>  setting  value
#>  version  R version 4.0.5 (2021-03-31)
#>  os       Red Hat Enterprise Linux
#>  system   x86_64, linux-gnu
#>  ui       X11
#>  language (EN)
#>  collate  en_GB.UTF-8
#>  ctype    en_GB.UTF-8
#>  tz       Europe/London
#>  date     2023-04-05
#>  pandoc   2.14.0.3 @ /usr/lib/rstudio-server/bin/pandoc/ (via rmarkdown)
#> 
#> ─ Packages ───────────────────────────────────────────────────────────────────
#>  package     * version date (UTC) lib source
#>  cli           3.6.0   2023-01-09 [1] CRAN (R 4.0.5)
#>  digest        0.6.31  2022-12-11 [1] CRAN (R 4.0.5)
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#>  fastmap       1.1.0   2021-01-25 [1] CRAN (R 4.0.5)
#>  fs            1.6.1   2023-02-06 [1] CRAN (R 4.0.5)
#>  glue          1.6.2   2022-02-24 [1] CRAN (R 4.0.5)
#>  htmltools     0.5.4   2022-12-07 [1] CRAN (R 4.0.5)
#>  knitr         1.42    2023-01-25 [1] CRAN (R 4.0.5)
#>  lifecycle     1.0.3   2022-10-07 [1] CRAN (R 4.0.5)
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#>  pkgconfig     2.0.3   2019-09-22 [1] CRAN (R 4.0.5)
#>  purrr         0.3.4   2020-04-17 [1] CRAN (R 4.0.5)
#>  R.cache       0.16.0  2022-07-21 [1] CRAN (R 4.0.5)
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#>  reprex        2.0.1   2021-08-05 [2] CRAN (R 4.0.5)
#>  rlang         1.0.6   2022-09-24 [1] CRAN (R 4.0.5)
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#>  rstudioapi    0.13    2020-11-12 [2] CRAN (R 4.0.5)
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#>  styler        1.8.1   2022-11-07 [1] CRAN (R 4.0.5)
#>  tibble      * 3.1.8   2022-07-22 [1] CRAN (R 4.0.5)
#>  utf8          1.2.2   2021-07-24 [1] CRAN (R 4.0.5)
#>  vctrs         0.5.0   2022-10-22 [1] CRAN (R 4.0.5)
#>  withr         2.5.0   2022-03-03 [1] CRAN (R 4.0.5)
#>  xfun          0.37    2023-01-31 [1] CRAN (R 4.0.5)
#>  yaml          2.3.7   2023-01-23 [1] CRAN (R 4.0.5)
#> 
#>  [1] /home/333573/R/x86_64-pc-linux-gnu-library/4.0
#>  [2] /opt/R/4.0.5/lib/R/library
#> 
#> ──────────────────────────────────────────────────────────────────────────────

[krlmlr]

Thanks. The second argument to as.POSIXct() is tz, on my system.

library(tibble)
chr_date <- "05/04/23 19:22:21"

tibble(
  a = as.POSIXct(chr_date, "%d/%m/%y %H:%M:%S", tz = "UTC"),
  b = as.POSIXct(chr_date, "%d/%m/%y %H:%M:%S")
)
#> Warning in strptime(xx, f, tz = tz): unknown timezone '%d/%m/%y %H:%M:%S'
#> Warning in as.POSIXct.POSIXlt(x): unknown timezone '%d/%m/%y %H:%M:%S'
#> Warning in strptime(xx, f, tz = tz): unknown timezone '%d/%m/%y %H:%M:%S'
#> Warning in as.POSIXct.POSIXlt(x): unknown timezone '%d/%m/%y %H:%M:%S'
#> Warning in strptime(x, f, tz = tz): unknown timezone '%d/%m/%y %H:%M:%S'
#> Warning in as.POSIXct.POSIXlt(as.POSIXlt(x, tz, ...), tz, ...): unknown
#> timezone '%d/%m/%y %H:%M:%S'
#> # A tibble: 1 × 2
#> Warning in as.POSIXlt.POSIXct(x, tz): unknown timezone '%d/%m/%y %H:%M:%S'
#> Warning in as.POSIXlt.POSIXct(x, tz): unknown timezone '%d/%m/%y %H:%M:%S'
#>   a                   b                  
#>   <dttm>              <dttm>             
#> 1 2023-04-05 19:22:21 0005-04-23 19:22:21

as.POSIXct(chr_date, "%d/%m/%y %H:%M:%S", tz = "UTC")
#> [1] "2023-04-05 19:22:21 UTC"
as.POSIXct(chr_date, "%d/%m/%y %H:%M:%S")
#> Warning in strptime(xx, f, tz = tz): unknown timezone '%d/%m/%y %H:%M:%S'
#> Warning in as.POSIXct.POSIXlt(x): unknown timezone '%d/%m/%y %H:%M:%S'
#> Warning in strptime(xx, f, tz = tz): unknown timezone '%d/%m/%y %H:%M:%S'
#> Warning in as.POSIXct.POSIXlt(x): unknown timezone '%d/%m/%y %H:%M:%S'
#> Warning in strptime(x, f, tz = tz): unknown timezone '%d/%m/%y %H:%M:%S'
#> Warning in as.POSIXct.POSIXlt(as.POSIXlt(x, tz, ...), tz, ...): unknown
#> timezone '%d/%m/%y %H:%M:%S'
#> Warning in as.POSIXlt.POSIXct(x, tz): unknown timezone '%d/%m/%y %H:%M:%S'
#> [1] "0005-04-23 19:22:21 GMT"
as.POSIXct(chr_date, format = "%d/%m/%y %H:%M:%S")
#> [1] "2023-04-05 19:22:21 CEST"

^{Created on 2024-12-15 with reprex v2.1.1}

Also trying with R 4.0.