1 #-*- coding:utf-8 -*-
 2 __author__ = ‘Administrator‘
 3 
 4 from collections import deque
 5 
 6 def search(lines, pattern, history=5):
 7     previons_line = deque(maxlen=history)
 8     for line in lines:
 9         if pattern in line:
10             yield line, previons_line
11         previons_line.append(line)
12 
13 
14 # Example use on a file
15 if __name__ == ‘__main__‘:
16     with open(‘.\somefile.txt‘) as f:
17         for line, prevlines in search(f, ‘python‘, 5):
18             for pline in prevlines:
19                 print(pline)
20             print(line, "end=‘‘")
21             print(‘-‘*20)
22           
23