python无需逐行替换文本文件中的单词

Question

我有一个文本文件，比如:

This is a text document
written in notepad

我想用"file"一词替换“文档”，用“记事本”一词替换“记事本”，然后我想保存/覆盖文件。现在，无需逐行进行，因为我知道我可以做到

wordReplacements = {'document':'file', 'notepad':'Notepad'}
contents = open(filePath, 'r')
for line in contents:
    for key, value in wordReplacements.iteritems():
        line = line.replace(key, value)
contents.close()

但是有没有办法不用一行一行地做呢？注意:我使用的是 python 2.7。

Answer 1

引自docs ,

For reading lines from a file, you can loop over the file object. This is memory efficient, fast, and leads to simple code

如果我是你，我会这样做

import os
wordReplacements = {'document':'file', 'notepad':'Notepad'}

def transform_line(line):
    for key, value in wordReplacements.iteritems():
        line = line.replace(key, value)
    return line

with open("Output.txt", "w") as output_file, open("Input.txt") as input_file:
    for line in input_file:
        output_file.write(transform_line(line))

os.rename("Output.txt", "Input.txt")

如果你更喜欢单行代码，你可以用这个替换 with 部分

with open("Output.txt", "w") as output_file, open("Input.txt") as input_file:
    output_file.write("".join(transform_line(line) for line in input_file))

如果内存不是问题，而你又不想遍历文件对象，你可以将整个文件的内容移动到内存，然后在那里替换它

import re
with open("Input.txt") as open_file:
    data = open_file.read()
for key, value in wordReplacements.iteritems():
    data = re.sub(key, value, data)
with open("Input.txt", "wb") as open_file:
    open_file.write(data)