Oh, that's right, the second arg is escaped by re compiler too. Thank you, John.
York John Machin wrote: > York wrote: > >>I have two backslash - a. and I want to replace them with one backslash, >>but I failed: >> >> >>> import re >> >>> a = '\\\\' >> >>> re.sub(r'\\\\', '\\', '\\\\') >>Traceback (most recent call last): >> File "<stdin>", line 1, in ? >> File "/usr/lib/python2.3/sre.py", line 143, in sub >> return _compile(pattern, 0).sub(repl, string, count) >> File "/usr/lib/python2.3/sre.py", line 258, in _subx >> template = _compile_repl(template, pattern) >> File "/usr/lib/python2.3/sre.py", line 245, in _compile_repl >> raise error, v # invalid expression >>sre_constants.error: bogus escape (end of line) >> >>> >> >>anybody knows why? > > > Yep. There are *two* levels of escaping happening (1) Python compiler > (2) re compiler (in the first two args, but of course only Python in > the 3rd). > To get your single backslash you need to start out with four cooked or > two raw: > > | >>> re.sub(r'\\\\', '\\\\', '\\\\') > '\\' > | >>> re.sub(r'\\\\', r'\\', '\\\\') > '\\' > > Cheers, > John > -- http://mail.python.org/mailman/listinfo/python-list
