python regex for repeating string

Question

I am wanting to verify and then parse this string (in quotes):

string = \"start: c12354, c3456, 34526; other stuff that I don\'t care about\"
//Note that som         


        

Answer 1

This can be done (pretty elegantly) with a tool like Pyparsing:

from pyparsing import Group, Literal, Optional, Word
import string

code = Group(Optional(Literal("c"), default='') + Word(string.digits) + Optional(Literal(","), default=''))
parser = Literal("start:") + OneOrMore(code) + Literal(";")
# Read lines from file:
with open('lines.txt', 'r') as f:
    for line in f:
        try:
            result = parser.parseString(line)
            codes = [c[1] for c in result[1:-1]]
            # Do something with teh codez...
        except ParseException exc:
            # Oh noes: string doesn't match!
            continue

Cleaner than a regular expression, returns a list of codes (no need to string.split), and ignores any extra characters in the line, just like your example.