Using weekdays with any locale under Windows

Question

I\'m trying to get the day of the week, and have it work consistently in any locale. In locales with Latin alphabets, everything is fine.

Sys.getlocale()
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Answer 1

The RStudio/Architect problem

This can be solved, slightly messily, by explicitly changing the encoding of the weekdays string to UTF-8.

current_codepage <- as.character(l10n_info()$codepage)
iconv(weekdays(Sys.Date()), from = current_codepage, to = "utf8")

Note that codepages only exist on Windows; l10n_info()$codepage is NULL on Linux.

The LC_TIME problem

It turns out that under Windows you have to set both the LC_CTYPE and LC_TIME locale categories, and you have to set LC_CTYPE before LC_TIME, or it won't work.

---

In the end, we need different implementations for different OSes.

Windows version:

get_today_windows <- function(locale = NULL)
{
  if(!is.null(locale))
  {
    lc_ctype <- Sys.getlocale("LC_CTYPE")
    lc_time <- Sys.getlocale("LC_TIME")
    on.exit(Sys.setlocale("LC_CTYPE", lc_ctype))
    on.exit(Sys.setlocale("LC_TIME", lc_time), add = TRUE)
    Sys.setlocale("LC_CTYPE", locale)
    Sys.setlocale("LC_TIME", locale)
  }
  today <- weekdays(Sys.Date())
  current_codepage <- as.character(l10n_info()$codepage)
  iconv(today, from = current_codepage, to = "utf8")
}
get_today_windows() 
## [1] "Tuesday"
get_today_windows("French_France")
## [1] "mardi"
get_today_windows("Arabic_Qatar")
## [1] "الثلاثاء"
get_today_windows("Serbian (Cyrillic)") 
## [1] "уторак"
get_today_windows("Chinese (Traditional)_Taiwan") 
## [1] "星期二"

Linux version:

get_today_linux <- function(locale = NULL)
{
  if(!is.null(locale))
  {
    lc_time <- Sys.getlocale("LC_TIME")
    on.exit(Sys.setlocale("LC_TIME", lc_time), add = TRUE)
    Sys.setlocale("LC_TIME", locale)
  }
  weekdays(Sys.Date())
}
get_today_linux() 
## [1] "Tuesday"
get_today_linux("fr_FR.utf8")
## [1] "mardi"
get_today_linux("ar_QA.utf8")
## [1] "الثلاثاء"
get_today_linux("sr_RS.utf8") 
## [1] "уторак"
get_today_linux("zh_TW.utf8") 
## [1] "週二"

Enforcing the .utf8 encoding in the locale seems important get_today_linux("zh_TW") doesn't display properly.