How to loop through directories and clean files?

Question

I am trying to loop through directories. My goal is to open the directory ff for modifications in the files.

When I try open (ff, 'r') it does not work.

Further, the files in the directories d.txt has numbers and symbols x, 1, " in every line. I am seeking to remove these characters from each line.

import os

filenames= os.listdir (".")
for filename in filenames:
    ff = os.path.join(r'C:\Users\V\Documents\f\e\e\data', filename, 'd.txt')

f = open(str(ff),'r')  #this line does not open the file
a = ['x','1','"']
lst = []
for line in f:
    for word in a:
        if word in line:
            line = line.replace(word,'')
            lst.append(line)
        f.close()

The Error that I am getting:

for line in f:
    ValueError: I/O operation on closed file.

That exception is not produced in the code we see. There is no I/O operation here. — zvone, Jul 15 '20 at 13:56
I belive you are doing the write operation outside the scope of file open, hence I/O error. — Shravan40, Jul 15 '20 at 13:56
Well you close the file with `f.close()` on the first iteration of `for word in a`, so if there's more than one word in the file it'll try to write to a closed file on the next iteration. You have to move that line out of the loops. — Guy Incognito, Jul 15 '20 at 14:24
Why do you think that the line you've commented doesn't open the file? The error message doesn't say anything about that line or about opening a file at all. The problem is trying to *close* the file multiple times, like I said before. — Guy Incognito, Jul 15 '20 at 14:35
@Green, If you need help debugging code that you have written, you must post a [Minimal, Complete, and Verifiable example](https://stackoverflow.com/help/mcve) and explain the specific problem with your code. — Sabito stands with Ukraine, Jul 15 '20 at 14:54

score 4 · Accepted Answer · answered Jul 15 '20 at 14:38

First of all, I think this part is wrong in your code:

    for filename in filenames:
        ff = os.path.join(r'C:\Users\V\Documents\f\e\e\data', filename, 'd.txt')

As this will assign the last filename to ff. So I have moved the following code under this for loop. Now it will run for all files.

I belive this code should work:

import os 

filenames = os.listdir('.')

lst = []
a = ['x','1','"']

for filename in filenames:
    ff = os.path.join(r'C:\Users\V\Documents\f\e\e\data', filename, 'd.txt')
    
    with open(ff,'r') as file:
        for line in file:
            for word in a:
                if word in line:
                    line = line.replace(word,'')
                    lst.append(line)
                    
    with open(ff,'w') as file:
        for line in lst:
            file.write(line)

Edit: if the open('ff','r') line doesn't work then maybe the path you are giving is wrong. What are the contents of filenames? And why are you adding d.txt at the end?? Please edit your post and add these details.

Yes this code works,it loop through directories, but somehow ' " ' quatation marks are not removed. — Green, Jul 15 '20 at 14:55
Please see this: https://stackoverflow.com/a/40950987/11573842 — Sabito stands with Ukraine, Jul 15 '20 at 14:57
The file needs closing. Without they are being ruined. lines from the last file are beeing saved in differen folder's file. but open(ff) works. So maybe this is a different question — Green, Jul 15 '20 at 15:07
@Green Please read this https://stackoverflow.com/a/19508772/11573842 — Sabito stands with Ukraine, Jul 15 '20 at 15:12

score 3 · Answer 2 · answered Jul 15 '20 at 14:55

Move f.close() to outside of loop. You're closing the file everytime loop runs.

import os

filenames= os.listdir (".")
for filename in filenames:
    ff = os.path.join(r'C:\Users\V\Documents\f\e\e\data', filename, 'd.txt')

f = open(str(ff),'r')  #this line does not open the file
a = ['x','1','"']
lst = []
for line in f:
    for word in a:
        if word in line:
            line = line.replace(word,'')
            lst.append(line)

f.close()

How to loop through directories and clean files?

2 Answers2