How to split a string by commas positioned outside of parenthesis?

by

One way to do it is to use findall with a regex that greedily matches things that can go between separators. eg:

>>> s = "Wilbur Smith (Billy, son of John), Eddie Murphy (John), Elvis Presley, Jane Doe (Jane Doe)"
>>> r = re.compile(r'(?:[^,(]|\([^)]*\))+')
>>> r.findall(s)
['Wilbur Smith (Billy, son of John)', ' Eddie Murphy (John)', ' Elvis Presley', ' Jane Doe (Jane Doe)']

The regex above matches one or more:

  • non-comma, non-open-paren characters
  • strings that start with an open paren, contain 0 or more non-close-parens, and then a close paren

One quirk about this approach is that adjacent separators are treated as a single separator. That is, you won’t see an empty string. That may be a bug or a feature depending on your use-case.

Also note that regexes are not suitable for cases where nesting is a possibility. So for example, this would split incorrectly:

"Wilbur Smith (son of John (Johnny, son of James), aka Billy), Eddie Murphy (John)"

If you need to deal with nesting your best bet would be to partition the string into parens, commas, and everthing else (essentially tokenizing it — this part could still be done with regexes) and then walk through those tokens reassembling the fields, keeping track of your nesting level as you go (this keeping track of the nesting level is what regexes are incapable of doing on their own).

More Related Contents:

  1. Split string on whitespace in Python [duplicate]
  2. Split string based on regex
  3. Split string on commas but ignore commas within double-quotes?
  4. How would I get everything before a : in a string Python
  5. Python regex: splitting on pattern match that is an empty string
  6. Split string at every position where an upper-case word starts
  7. Splitting a math expression string into tokens in Python
  8. How do you split a list into evenly sized chunks?
  9. Match a whole word in a string using dynamic regex
  10. Case insensitive regular expression without re.compile?
  11. Python string.replace regular expression [duplicate]
  12. Split a string at uppercase letters
  13. Regex matching 5-digit substrings not enclosed with digits
  14. How to split but ignore separators in quoted strings, in python?
  15. Regular expression to extract URL from an HTML link
  16. BeautifulSoup – search by text inside a tag
  17. Splitting a semicolon-separated string to a dictionary, in Python
  18. How do I split a string into a list?
  19. Get the string within brackets in Python
  20. Quickest way to make a get_dummies type dataframe from a column with a multiple of strings
  21. Split string based on a regular expression
  22. Attribute Error: ‘list’ object has no attribute ‘split’
  23. Python – Locating the position of a regex match in a string?
  24. Python unicode regular expression matching failing with some unicode characters -bug or mistake?
  25. How can I make multiple replacements in a string using a dictionary?
  26. Python regex split without empty string
  27. Warning raised by inserting 4-byte unicode to mysql
  28. Python: Replace with regex
  29. Remove non-ASCII characters from a string using python / django
  30. How to strip whitespace from before but not after punctuation in python

Leave a Comment