How do I search for a pattern within a text file using Python combining regex & string/file operations and store instances of the pattern?

Question

So essentially I\'m looking for specifically a 4 digit code within two angle brackets within a text file. I know that I need to open the text file and then parse line by lin

Answer 1

import re
pattern = re.compile("<(\d{4,5})>")

for i, line in enumerate(open('test.txt')):
    for match in re.finditer(pattern, line):
        print 'Found on line %s: %s' % (i+1, match.group())

A couple of notes about the regex:

• You don't need the ? at the end and the outer (...) if you don't want to match the number with the angle brackets, but only want the number itself
• It matches either 4 or 5 digits between the angle brackets

Update: It's important to understand that the match and capture in a regex can be quite different. The regex in my snippet above matches the pattern with angle brackets, but I ask to capture only the internal number, without the angle brackets.

More about regex in python can be found here : Regular Expression HOWTO