Change german month abbreviation in full name of the month in R

Question

I would like to change german month abbreviations like "Jan", "Feb", "Mär, "Apr", "Mai", and so on, to the full name of the months. Like "Januar", "Februar", "März", ...

I guess there is no such function available. For English abbreviations, there is the function month.abb. Do you have an idea how I could do this not manually?

Thanks a lot

Answer 1

You can get full month name in the current locale with:

format(ISOdate(2000, 1:12, 1), "%B")
#months(ISOdate(2000, 1:12, 1)) #Alternative

and abbreviated month name in the current locale with:

format(ISOdate(2000, 1:12, 1), "%b")
#months(ISOdate(2000, 1:12, 1), TRUE) #Alternative

To change the locale have a look at How to change the locale of R? in case Sys.setlocale("LC_TIME", "de_DE.UTF-8") is not working.

And to make the conversion local short to local long:

loc2loc <- setNames(format(ISOdate(2000, 1:12, 1), "%B"), format(ISOdate(2000, 1:12, 1), "%b"))
loc2loc["Jan"]

and local short to English long:

loc2eng <- setNames(month.name, format(ISOdate(2000, 1:12, 1), "%b"))
loc2eng["Jan"]

Or without using locales - hard coded:

de2de <- setNames(c("Januar", "Februar", "März", "April", "Mai", "Juni", "Juli"
  , "August", "September", "Oktober", "November", "Dezember"), c("Jan", "Feb"
  , "Mär", "Apr", "Mai", "Jun", "Jul", "Aug", "Sep", "Okt", "Nov", "Dez"))
de2de[c("Jan", "Feb", "Mär", "Apr", "Mai")]
#      Jan       Feb      Mär       Apr       Mai 
# "Januar" "Februar"   "März"   "April"     "Mai" 

Answer 2

This is what the function match solves.

Using the built-in English names, you’d write

example_data = c('Jan', 'Dec', 'Mar')
month.name[match(example_data, month.abb)]

The same works for other languages, you’ll just have to define your own vectors for the month names and abbreviations.