How to grep lines between two patterns in a big file with python

Question

I have a very big file, like this:

[PATTERN1]
line1
line2
line3 
...
...
[END PATTERN]
[PATTERN2]
line1 
line2
...
...
[END PATTERN]

I need to extract

Answer 1

i would go with a generator-based solution

#!/usr/bin/env python    
start_patterns = ('PATTERN1', 'PATTERN2')
end_patterns = ('END PATTERN')

def section_with_bounds(gen):
  section_in_play = False
  for line in gen:
    if line.startswith(start_patterns):
      section_in_play = True
    if section_in_play:
      yield line
    if line.startswith(end_patterns):
      section_in_play = False

with open("text.t2") as f:
  gen = section_with_bounds(f)
  for line in gen:
    print line