How to grab number after word in python

Question

I have a huge file containing the following lines DDD-1126N|refseq:NP_285726|uniprotkb:P00112 and DDD-1081N|uniprotkb:P12121, I want to grab the number after uniprotkb.

Here's my code:

x = 'uniprotkb:P'
f = open('m.txt')
for line in f:
  print line.find(x) 
  print line[36:31 + len(x)]

The problem in line.find(x) is 10 and 26, I grab the complete number when it is 26. I'm new to programming, so I'm looking for something to grab the complete number after the word.

x = 'uniprotkb:'
f = open('m.txt')
for line in f:
  if x in line:
    print the number after x

Answer 1

Use regular expressions:

import re
for line in open('m.txt'):
    match = re.search('uniprotkb:P(\d+)', line)
    if match:
        print match.group(1)