Python find string in file, edit line and save to a new file

Question

I'm trying to go through a text file and find all the lines that start with 'file='. When I find these lines I want to remove all the text in between the dots and finally save that as a new file.

Such lines look like so

file="image.&!145.jpg"

I'm currently stuck to the place where I either:

delete the text between dots all over the file (not just the lines that start with 'file=')
delete the text between the dots only on the lines that start with 'file=', but I only end up saving that single line in the new document.

Here's the code that I have so far:

import os
from os.path import basename
from re import sub


file_in = 'tex_file_01.txt'
file_out = 'tex_file_01_new.txt'


with open(file_in, 'r') as f_in:
    with open(file_out, 'w') as f_out:
        for line in f_in:
            if 'file=' in line:
                print 'found: ' + line

            line_fix = sub('\..*?\.', '.', line)
            print 'fixed: ' + line_fix

            f_out.write(line.replace(line, line_fix))

The above piece of code deletes the text between the dots all over the file.

Any ideas? Thanks in advance!

did you try adding line_fix = sub('\..*?\.', '.', line) in the IF statement itself rather than writing it outside ? — sdgd
– sdgd, Commented Jan 3, 2018 at 14:19
Quick look would suggest you just need to indent the lines after the if so that they are only done when you find a line of interest, then append an else: f_out.write(line)) — cdarke
– cdarke, Commented Jan 3, 2018 at 14:19

Femkemilene · Accepted Answer · 2022-02-15 02:08:38Z

2

Try this out. The only error I see is that portion which comes in the if condition. You are editing all lines of the file.

import os
from os.path import basename
from re import sub


file_in = 'tex_file_01.txt'
file_out = 'tex_file_01_new.txt'


with open(file_in, 'r') as f_in:
    with open(file_out, 'w') as f_out:
        for line in f_in:
            if 'file=' in line:
                print('found: ' + line)
                line_fix = sub('\..*?\.', '.', line)
            else:
                line_fix = line
            print('fixed: ' + line_fix)
            
            f_out.write(line.replace(line, line_fix))

edited Feb 15, 2022 at 2:08

Femkemilene

3054 silver badges16 bronze badges

answered Jan 3, 2018 at 14:25

Himanshu sharma

8,0536 gold badges48 silver badges82 bronze badges

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