Python 替换文件内容中的字符串

Replace string within file contents

提问by Joey

How can I open a file, Stud.txt, and then replace any occurences of "A" with "Orange"?

如何打开文件 Stud.txt，然后将出现的任何“A”替换为“Orange”？

回答by Gareth Davidson

with open("Stud.txt", "rt") as fin:
    with open("out.txt", "wt") as fout:
        for line in fin:
            fout.write(line.replace('A', 'Orange'))

回答by Falmarri

with open('Stud.txt','r') as f:
    newlines = []
    for line in f.readlines():
        newlines.append(line.replace('A', 'Orange'))
with open('Stud.txt', 'w') as f:
    for line in newlines:
        f.write(line)

回答by TartanLlama

Something like

就像是

file = open('Stud.txt')
contents = file.read()
replaced_contents = contents.replace('A', 'Orange')

<do stuff with the result>

回答by austinbv

easiest way is to do it with regular expressions, assuming that you want to iterate over each line in the file (where 'A' would be stored) you do...

最简单的方法是用正则表达式来做，假设你想遍历文件中的每一行（'A' 将被存储）你这样做......

import re

input = file('C:\full_path\Stud.txt), 'r')
#when you try and write to a file with write permissions, it clears the file and writes only #what you tell it to the file.  So we have to save the file first.

saved_input
for eachLine in input:
    saved_input.append(eachLine)

#now we change entries with 'A' to 'Orange'
for i in range(0, len(old):
    search = re.sub('A', 'Orange', saved_input[i])
    if search is not None:
        saved_input[i] = search
#now we open the file in write mode (clearing it) and writing saved_input back to it
input = file('C:\full_path\Stud.txt), 'w')
for each in saved_input:
    input.write(each)

回答by Adam Matan

If you'd like to replace the strings in the same file, you probably have to read its contents into a local variable, close it, and re-open it for writing:

如果您想替换同一文件中的字符串，您可能必须将其内容读入一个局部变量，关闭它，然后重新打开它以进行写入：

I am using the with statementin this example, which closes the file after the withblock is terminated - either normally when the last command finishes executing, or by an exception.

我在这个例子中使用了 with 语句，它在with块终止后关闭文件——通常是在最后一个命令完成执行时，或者在异常时。

def inplace_change(filename, old_string, new_string):
    # Safely read the input filename using 'with'
    with open(filename) as f:
        s = f.read()
        if old_string not in s:
            print('"{old_string}" not found in {filename}.'.format(**locals()))
            return

    # Safely write the changed content, if found in the file
    with open(filename, 'w') as f:
        print('Changing "{old_string}" to "{new_string}" in {filename}'.format(**locals()))
        s = s.replace(old_string, new_string)
        f.write(s)

It is worth mentioning that if the filenames were different, we could have done this more elegantly with a single withstatement.

值得一提的是，如果文件名不同，我们可以用一条with语句更优雅地做到这一点。

回答by Mark Kahn

#!/usr/bin/python

with open(FileName) as f:
    newText=f.read().replace('A', 'Orange')

with open(FileName, "w") as f:
    f.write(newText)

回答by user1767754

If you are on linux and just want to replace the word dogwith catyou can do:

如果您在 linux 上并且只想dog用cat您可以替换这个词：

text.txt:

文本.txt：

Hi, i am a dog and dog's are awesome, i love dogs! dog dog dogs!

Linux Command:

Linux命令：

sed -i 's/dog/cat/g' test.txt

Output:

输出：

Hi, i am a cat and cat's are awesome, i love cats! cat cat cats!

Original Post: https://askubuntu.com/questions/20414/find-and-replace-text-within-a-file-using-commands

原帖：https: //askubuntu.com/questions/20414/find-and-replace-text-within-a-file-using-commands

回答by Jorge Moraleda

Using pathlib (https://docs.python.org/3/library/pathlib.html)

使用 pathlib ( https://docs.python.org/3/library/pathlib.html)

from pathlib import Path
file = Path('Stud.txt')
file.write_text(file.read_text().replace('A', 'Orange'))

If input and output files were different you would use two different variables for read_textand write_text.

如果输入和输出文件不同，您可以为read_text和使用两个不同的变量write_text。

If you wanted a change more complex than a single replacement, you would assign the result of read_textto a variable, process it and save the new content to another variable, and then save the new content with write_text.

如果您想要一个比单个替换更复杂的更改，您可以将 的结果分配read_text给一个变量，对其进行处理并将新内容保存到另一个变量中，然后使用write_text.

If your file was large you would prefer an approach that does not read the whole file in memory, but rather process it line by line as show by Gareth Davidson in another answer (https://stackoverflow.com/a/4128192/3981273), which of course requires to use two distinct files for input and output.

如果您的文件很大，您会更喜欢一种不读取内存中整个文件的方法，而是逐行处理它，如 Gareth Davidson 在另一个答案中所示（https://stackoverflow.com/a/4128192/3981273） ，这当然需要使用两个不同的文件进行输入和输出。