Question

So I have this regex:

(^(\s+)?(?P<NAME>(\w)(\d{7}))((01f\.foo)|(\.bar|\.goo\.moo\.roo))$|(^(\s+)?(?P<NAME2>R1_\d{6}_\d{6}_)((01f\.foo)|(\.bar|\.goo\.moo\.roo))$)) 

Now if I try and do a match against this:

 B048661501f.foo 

I get this error:

   File 'C:\Python25\lib\re.py', line 188, in compile     return _compile(pattern, flags)   File 'C:\Python25\lib\re.py', line 241, in _compile     raise error, v # invalid expression sre_constants.error: redefinition of group name 'NAME' as group 9; was group 3 

If I can’t define the same group twice in the same regex expression for two different cases, what do I do?

Answer 1

No, you can’t have two groups of the same name, this would somehow defy the purpose, wouldn’t it?

What you probably really want is this:

^\s*(?P<NAME>\w\d{7}|R1_(?:\d{6}_){2})(01f\.foo|\.(?:bar|goo|moo|roo))$ 

I refactored your regex as far as possible. I made the following assumptions:

You want to (correct me if I’m wrong):

• ignore white space at the start of the string
• match either of the following into a group named ‘NAME’:
  • a letter followed by 7 digits, or
  • 'R1_', and two times (6 digits + '_')
• followed by either:
  • '01f.foo' or
  • '.' and ('bar' or 'goo' or 'moo' or 'roo')
• followed by the end of the string

---

You could also have meant:

^\s*(?P<NAME>\w\d{7}01f|R1_(?:\d{6}_){2})\.(?:foo|bar|goo|moo|roo)$ 

Which is:

• ignore white space at the start of the string
• match either of the following into a group named ‘NAME’:
  • a letter followed by 7 digits and ’01f’
  • 'R1_', and two times (6 digits + '_')
• a dot
• 'foo', 'bar', 'goo', 'moo' or 'roo'
• the end of the string