python reg ex to include missing commas

Question

I need to ensure an string to have comma separated values. The strings I read may have space separated values.

• Some commas might be missing in my input string

Answer 1

PyParsing will definitely not be the fastest way to run this, but it is perhaps the fastest way to write it ;-)

from pyparsing import *

STRING = sglQuotedString | dblQuotedString
NONSTRING = Word(alphanums + '.-')
line = OneOrMore(STRING | NONSTRING | Suppress(',')) + lineEnd


def insert_commas(s):
    values = line.parseString(s).asList()
    return ", ".join(values)


s1 = """1, ' unchanged 1' " unchanged  2 "  2, 2"""
s2 = """1, ' unchanged 1', " unchanged 2 " ,  2, 2"""
s3 = """ 1, ' unchanged 1' " unchanged 2 " 2, 2 45"""
s4 = """1, 67.90e-34 67.90E-34 7.9093339333 2, 2 """

print insert_commas(s1)
print insert_commas(s2)
print insert_commas(s3)
print insert_commas(s4)

which prints

1, ' unchanged 1', " unchanged  2 ", 2, 2
1, ' unchanged 1', " unchanged 2 ", 2, 2
1, ' unchanged 1', " unchanged 2 ", 2, 2, 45
1, 67.90e-34, 67.90E-34, 7.9093339333, 2, 2