Python regex findall

Question

I am trying to extract all occurrences of tagged words from a string using regex in Python 2.7.2. Or simply, I want to extract every piece of text inside the [p][/p] tags. Here is my attempt:

regex = ur"[\u005B1P\u005D.+?\u005B\u002FP\u005D]+?" line = "President [P] Barack Obama [/P] met Microsoft founder [P] Bill Gates [/P], yesterday." person = re.findall(pattern, line) 

Printing person produces ['President [P]', '[/P]', '[P] Bill Gates [/P]']

What is the correct regex to get: ['[P] Barack Obama [/P]', '[P] Bill Gates [/p]'] or ['Barrack Obama', 'Bill Gates'].

Answer 1

import re regex = ur"\[P\] (.+?) \[/P\]+?" line = "President [P] Barack Obama [/P] met Microsoft founder [P] Bill Gates [/P], yesterday." person = re.findall(regex, line) print(person) 

yields

['Barack Obama', 'Bill Gates'] 

---

The regex ur"[\u005B1P\u005D.+?\u005B\u002FP\u005D]+?" is exactly the same unicode as u'[[1P].+?[/P]]+?' except harder to read.

The first bracketed group [[1P] tells re that any of the characters in the list ['[', '1', 'P'] should match, and similarly with the second bracketed group [/P]].That's not what you want at all. So,

• Remove the outer enclosing square brackets. (Also remove the stray 1 in front of P.)
• To protect the literal brackets in [P], escape the brackets with a backslash: \[P\].
• To return only the words inside the tags, place grouping parentheses around .+?.