ランダムにn行出力

gistfile1.py

#!/usr/bin/env python
# coding: utf-8

import sys
import random
import argparse

def main(filename, linecount):
    with open(filename, 'r') as f:
        _l = sum(1 for _ in f)
        f.seek(0)
        pick = sorted(random.sample(range(_l), min(_l, linecount)))
        last = 0
        for idx, line in zip(xrange(_l), f):
            if idx == pick[last]:
                print line,
                last += 1
            if last >= linecount: break

if __name__ == '__main__':

    parser = argparse.ArgumentParser()
    parser.add_argument('filename')
    parser.add_argument('-n', type=int)

    args = parser.parse_args()

    main(args.filename, args.n)