How do I case fold a string in Python 2?

Question

Python 3.3 adds the casefold method to the str type, but in 2.x I don\'t have anything. What\'s the best way to work around this?

Answer 1

If PyICU is already installed; you could use it to define casefold(). Using the same example strings as in @Russ' answer:

>>> import icu
>>> casefold = lambda u: unicode(icu.UnicodeString(u).foldCase())
>>> print casefold(u"tschüß")
tschüss
>>> casefold(u"ΣίσυφοςfiÆ") == casefold(u"ΣΊΣΥΦΟσFIæ") == u"σίσυφοσfiæ"
True
>>> icu.UNICODE_VERSION
'6.3'
>>> import unicodedata
>>> unicodedata.unidata_version
'5.2.0'

The result may depend on the version of Unicode standard.