How to reading .txt file and rewriting by adding space after specific position / index for each line in python

Question

I want to read .txt file and add space after a specific position/index for each line. please consider below example for more details.

suppose my file contains

Answer 1

Consider this:

space_indecies = [2, 5, 8]

with open("C:/path-to-file/file.txt", "r") as file:
    lines = file.read().split("\n")
newlines = []
for line in lines:
    line = line.rstrip()
    for n, i in enumerate(space_indecies):
        line = line[:i + n] + ' ' + line[n + i:]
    newlines.append(line)
with open("C:/path-to-file/file.txt", "w") as newfile:  
    newfile.write("\n".join(newlines))

The i + n is needed, because the index where you want to insert your space shifts with every space inserted