python and regular expression with unicode

Question

I need to delete some unicode symbols from the string 'بِسْمِ اللَّهِ الرَّحْمَٰنِ الرَّحِيمِ'

I know they exist here for sure. I try:

re.sub('([\u064B-\u0652\u06D4\u0670\u0674\u06D5-\u06ED]+)', '', 'بِسْمِ اللَّهِ الرَّحْمَٰنِ الرَّحِيمِ')

but it doesn't work. String stays the same. ant suggestion what i do wrong?

Answer 1

Are you using python 2.x or 3.0?

If you're using 2.x, try making the regex string a unicode-escape string, with 'u'. Since it's regex it's good practice to make your regex string a raw string, with 'r'. Also, putting your entire pattern in parentheses is superfluous.

re.sub(ur'[\u064B-\u0652\u06D4\u0670\u0674\u06D5-\u06ED]+', '', ...)

http://docs.python.org/tutorial/introduction.html#unicode-strings

Edit:

It's also good practice to use the re.UNICODE/re.U/(?u) flag for unicode regexes, but it only affects character class aliases like \w or \b, of which this pattern does not use any and so would not be affected by.

Answer 2

Use unicode strings. Use the re.UNICODE flag.

>>> myre = re.compile(ur'[\u064B-\u0652\u06D4\u0670\u0674\u06D5-\u06ED]+', 
                      re.UNICODE)
>>> myre
<_sre.SRE_Pattern object at 0xb20b378>
>>> mystr = u'بِسْمِ اللَّهِ الرَّحْمَٰنِ الرَّحِيمِ'
>>> result = myre.sub('', mystr)
>>> len(mystr), len(result)
(38, 22)
>>> print result
بسم الله الرحمن الرحيم

Read the article by Joel Spolsky called The Absolute Minimum Every Software Developer Absolutely, Positively Must Know About Unicode and Character Sets (No Excuses!)

Answer 3

ur'[\u064B-\u0652\u06D4\u0670\u0674\u06D5-\u06ED]+

Does prefix 'ur' means that: escape the unicode character but left other unchanged?