替换文件内容中的字符串

Question

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

Answer 1

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

Answer 2

如果你想替换同一个文件中的字符串，你可能需要将它的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：

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)

值得一提的是，如果文件名不同，我们可以用一条with语句更优雅地完成这项工作。

Answer 3

#!/usr/bin/python with open(FileName) as f: newText=f.read().replace('A', 'Orange') with open(FileName, "w") as f: f.write(newText)

Answer 4

就像是

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

<do stuff with the result>

Answer 5

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)

Answer 6

如果您使用的是 linux 并且只想用cat替换单词dog ，您可以执行以下操作：

文本.txt：

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

Linux命令：

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

输出：

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

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

Answer 7

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'))

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

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

如果您的文件很大，您会更喜欢一种不读取内存中的整个文件的方法，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。

Answer 8

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)