Question

我有这个文本文件names.txt

Daniel
Sam
Sameer
Code
Print
Alpha
Bravo
Charlie

我想搜索字符串＆＃34; Alpha＆＃34;并复制该行＆＃34; alpha＆＃34;之前的100行然后写＆＃34;追加＆＃34;它来归档result.txt

 with open(names.txt) as g:
    lines = (g.readlines())
    for line in lines:
        if "{0}".format("Alpha") in line:
          ????????????

我写了这个代码并停在这里，任何人都可以帮忙吗？

Answer 1

最简单的方法可能是维护您已阅读的最后100行的列表，如果当前行为result.txt，则将其输出到'Alpha'文件：< / p>

limit = 100
prev_items = []

# Open file and iterate over lines.
with open('names.txt') as f:
    for line in f:
        # Add the current line to the list.
        prev_items.append(line)
        # Reduce the list to its newest elements.
        prev_items = prev_items[-limit:]

        # If the current line is 'Alpha', we don't need to read any more.
        if line == 'Alpha':
           break

# Append prev_items to the results file.
with open('results.txt', 'a') as f:
    f.write('\n'.join(prev_items))

或者，如果您愿意使用list以外的收藏品，请使用deque：

from collections import deque

limit = 100
prev_items = deque(maxlen=limit)

# Open file and iterate over lines.
with open('names.txt') as f:
    for line in f:
        # Add the line to the deque.
        prev_items.append(line)

        # If the current line is 'Alpha', we don't need to read any more.
        if line == 'Alpha':
           break

# Append prev_items to the results file.
with open('results.txt', 'a') as f:
    f.write('\n'.join(prev_items))

Answer 2

你需要一个计数器来告诉你哪一行有Alpha，所以你可以返回并获得你需要的100行。

python搜索文本文件中的字符串并复制块

2 个答案: