28 lines
726 B
Python
28 lines
726 B
Python
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#!/usr/bin/env python
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# -*- encoding: utf-8 -*-
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"""
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Topic: collections.deque演示
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Desc : deque有一个maxlen参数，当append的时候，如果超过，那么最前面的就被挤出队列。
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"""
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from collections import deque
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def search(lines, pattern, history=5):
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previous_lines = deque(maxlen=history)
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for li in lines:
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if pattern in li:
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yield li, previous_lines
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previous_lines.append(li)
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# Example use on a file
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if __name__ == '__main__':
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with open(r'../../cookbook/somefile.txt') as f:
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for line, prevlines in search(f, 'Python', 5):
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for pline in prevlines:
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print(pline, end='')
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print(line, end='')
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print('-' * 20)
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