regex result filter in python
Question: I am working on a program with regexes, I have to filter them but I can't find
out how. I want to match every red,xxxx or xxxx,red expression in my string
and put the colors xxxx into a group. Here is my code:

    
    
    string = "blue,red   red,yellow   blue,yellow   red,green   purple red, ..."
    regex = re.compile('(?:red,(?P<redfirst>\w+)|(?P<othercolorfirst>\w+),red)')
    

Then I write:

    
    
    for match in regex.finditer(string):
        if match.group('redfirst')!= "None":
            print(match.group("redfirst"))
    

But I still obtain printing like:

    
    
    None
    yellow
    green
    None
    

I dont want the 'None' results to appear, I have to skip them in an smart way
if possible. Thanks for help!

**EDIT** None without quotes doesn't work either


Answer: 
    >>> import re
    >>> regex = re.compile('(?:red,(?P<redfirst>\w+)|(?P<othercolorfirst>\w+),red)')
    
    >>> string = "blue,red   red,yellow   blue,yellow   red,green   purple red, ..."
    
    >>> for matches in regex.finditer(string):
    ...     if matches.group('redfirst'):
    ...         print matches.group('redfirst')
    ...
    yellow
    green
    >>>
    

