替換文件內容中的字符串

Question

如何打開文件 Stud.txt，然后將出現的任何“A”替換為“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

如果你想替換同一個文件中的字符串，你可能需要將它的內容讀入一個局部變量，關閉它，然后重新打開它以進行寫入：

我在這個例子中使用了 with 語句，它在with塊終止后關閉文件——通常是在最后一個命令完成執行時，或者在異常時。

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，我們可以用一條with語句更優雅地完成這項工作。

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 並且只想用cat替換單詞dog ，您可以執行以下操作：

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

輸出：

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'))

如果輸入和輸出文件不同，您可以為read_text和write_text使用兩個不同的變量。

如果您想要比單個替換更復雜的更改，您可以將read_text的結果分配給一個變量，對其進行處理並將新內容保存到另一個變量，然后使用write_text保存新內容。

如果您的文件很大，您會更喜歡一種不讀取內存中的整個文件的方法，而是逐行處理它，如 Gareth Davidson 在另一個答案中所示（ https://stackoverflow.com/a/4128192/3981273 ） ，這當然需要使用兩個不同的文件進行輸入和輸出。

Answer 8

最簡單的方法是用正則表達式來做，假設你想遍歷文件中的每一行（'A' 將被存儲）你這樣做......

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)