python - 使用python跳过文件中的最后5行

Question

我想使用 python 删除文件中的最后几行。该文件很大，所以要删除前几行，我使用以下代码

import sys
with open(sys.argv[1],"rb") as f:
    for _ in range(6):#skip first 6 lines
        next(f)
    for line in f:
        print line

Answer 1

这是一个用于截断任何可迭代对象的通用生成器:

from collections import deque

def truncate(iterable, num):
    buffer = deque(maxlen=num)
    iterator = iter(iterable)

    # Initialize buffer
    for n in range(num):
        buffer.append(next(iterator))

    for item in iterator:
        yield buffer.popleft()
        buffer.append(item)

truncated_range20 = truncate(range(20), 5)

print(list(truncated_range20))
# [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14]

使用截断，你可以这样做:

from __future__ import print_function

import sys

from itertools import islice


filepath = sys.argv[1]

with open(filepath, 'rb') as f:
    for line in truncate(islice(f, 6, None), 5):
        print(line, end='')