Regex : Remove all commas between a quote separated string [python]

Question

What would be an appropriate regex to remove all commas in a string as such:

12, 1425073747, \"test\", \"1, 2, 3, ... \"

Result:

Answer 1

This should work for you:

>>> input = '12, 1425073747, "test", "1, 2, 3, ... "';
>>> print re.sub(r'(?!(([^"]*"){2})*[^"]*$),', "", input);
12, 1425073747, "test", "1 2 3 ... "

(?!(([^"]*"){2})*[^"]*$) matches text only if inside quotea -- avoid matching even number of quotes after comma.

Answer 2

You may use a re.sub with a simple r'"[^"]*"' regex and pass the match object to a callable used as the replacement argument where you may further manipulate the match:

import re
text = '12, 1425073747, "test", "1, 2, 3, ... "'
print( re.sub(r'"[^"]*"', lambda x: x.group().replace(",", ""), text) )

See the Python demo.

If the string between quotes may contain escaped quotes use

re.sub(r'(?s)"[^"\\]*(?:\\.[^"\\]*)*"', lambda x: x.group().replace(",", ""), text)

Here, (?s) is the inline version of a re.S / re.DOTALL flag and the rest is the double quoted string literal matching pattern.

Bonus

• Removing all whitespace in between double quotes: re.sub(r'"[^"]*"', lambda x: ''.join(x.group().split()), text)
• Remove all non-digit chars inside double quotes: re.sub(r'"[^"]*"', lambda x: ''.join(c for c in x.group() if c.isdigit()), text)
• Remove all digit chars inside double quotes: re.sub(r'"[^"]*"', lambda x: ''.join(c for c in x.group() if not c.isdigit()), text)