如何在Python中读取和写入文本文件的多行

Question

I am trying to read and write multiple lines of a text file in Python. My goal is to specify the rows which I want to be changed with the input I give to the script. The script is working when specifying a single row, but not with multiple rows.

For example lets say I have this file:

Item 1
Item 2
Item 3

When trying to do the following for a single line it is working fine:

a_file = open("filename.yml", "r")
list_of_lines = a_file.readlines()
list_of_lines[1] = "Item: " + (input('Input: ')) + "\n"

a_file = open("filename.yml", "w")
a_file.writelines(list_of_lines)
a_file.close()

But I cant seem to figure out how to apply the same input for multiple lines of text file. What I've tried but didn't work:

a_file = open("filename.yml", "r")
list_of_lines = a_file.readlines()
list_of_lines[1][2] = "Item: " + (input('some input: ')) + "\n"

a_file = open("filename.yml", "w")
a_file.writelines(list_of_lines)
a_file.close()

Answer 1

Thy using a for loop:

with open('file.txt', 'r') as f:
    list_of_lines = f.readlines()
    t = f"Item {input('some input: ')}\n"
    for i in range(len(list_of_lines)):
        if i in [1, 2]:
            list_of_lines[i] = t

with open("file.txt", "w") as f:
    f.writelines(list_of_lines)

file.txt :

Item 1
Item 2
Item 3

Input:

some input: hello

Resulting file.txt :

Item 1
Item hello
Item hello

---

You can also use a list comprehension with the built-in enumerate method:

t = f"Item {input('some input: ')}\n"
d = [1, 2]

with open('file.txt', 'r') as f:
    list_of_lines = [t if i in d else v for i, v in enumerate(f)]
    
with open("file.txt", "w") as f:
    f.writelines(list_of_lines)