CODEWITHSUNDEEP
python
user1666375
user1666375

Reputation: 29

Script not writing to file

I would like to make it so that it opens up alan.txt, search the text for all instance of scholary_tehologian and if found, add the word "test" under it. when I tried doing it this way:

## Script
with open('alan.txt', 'r+') as f:
for line in f:
    if "scholarly_theologian" in line:
        f.write("test")

it wouldn't write anything. I'm in Windows 8.1

Upvotes: 0

Views: 122

Answers (3)

manicphase
manicphase

Reputation: 618

Rewritten answer because the last one was wrong.

If you want to read lines you have to put .readlines() after open(...) or f. Then there's a few ways you could insert "test".

 ## Script
with open('alan.txt', 'r') as f:
    lines = f.readlines()

for i in range(len(lines)):
    if "scholarly_theologian" in lines[i]:
         lines[i] = lines[i] + "\ntest"

with open('alan.txt', 'w') as f:
    f.write("\n".join(lines))

Upvotes: 1

Ella Sharakanski
Ella Sharakanski

Reputation: 2773

You can't modify a file like this. You can only append to it, write characters instead of others, or rewrite it entirely. See How do I modify a text file in Python?.

What you should do is create another file with the content you want.

EDIT:

Claudio's answer has the code for what I offered. It has the benefit (over manicphase's code) of not keeping the whole file in memory. This is important if the file is long. manicphase's answer, on the other hand, has the benefit of not creating a second file. It rewrites the original one. Choose the one that fits your needs.

Upvotes: 1

Claudiu
Claudiu

Reputation: 1829

This should do the trick:

with open('output.txt', 'w') as o:
    with open('alan.txt', 'r') as f:
        for line in f:
            o.write(line)
            if line.find('scholarly_theoligian'):
                o.write('test')

Like Ella Shar mentioned, you need to create a new file and add the new content into it.

If working with two files is not acceptable, the next step would be to delete the input file, and to rename the output file.

Upvotes: 0

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