Replace Text with Comma in File With Python

Question

#open file and rewrite (comma) to ,
with open('outputFile') as fo:
    fo.write(line.replace("(comma)"," , "))

I'm trying to replace the text (comma) with a literal , within a file. When I run the above code, I get the following error: io.UnsupportedOperation: not writable

Any insight as to how to rewrite text within a file would be greatly appreciated.

I've used the below code, and it still won't replace (comma) with ,

#open file and rewrite (comma) to , with open('outputFile.txt', "a+") as fo: fo.write(fo.replace('(comma)',',')) fo.close()

Nitesh Patel · Accepted Answer · 2015-07-14T20:14:10.580

3

You need to open the file in read/write mode using the 'r+' argument.

Once you read the file contents, clear it using seek(0) and truncate(), and then write the new text.

with open('outputFile', 'r+') as f:
    text = f.read()
    f.seek(0)
    f.truncate()
    f.write(text.replace('(comma)', ' , '))

edited Jul 14 '15 at 20:14

answered Jul 14 '15 at 19:38

Nitesh Patel

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DanielGibbs · Answer 2 · 2015-07-14T19:55:13.427

1

You get the "not writeable" error because you need to open the file for writing, done by passing the mode argument to open:

with open('outputFile', "w") as fo:
    fo.write(line.replace("(comma)"," , "))

Depending on the behaviour you want, you may want to use a mode other than "w", which truncates the file if it exists. Check out the Python documentation on open for more details.

If you still get an error then there may be a permissions problem writing to the file.

To actually perform a replacement on each line in the file have a look at this question or this question.

edited Jul 14 '15 at 19:55

answered Jul 14 '15 at 19:12

DanielGibbs

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2

where does `line` come from? – Brobin Jul 14 '15 at 19:12
It was in the original post. – DanielGibbs Jul 14 '15 at 19:12
1

From what I understood, OP is reading, replacing, and writing from/to the same file, in which case `line` is undefined. – Brobin Jul 14 '15 at 19:13
Does the new code in my above edit use `fo` and `line` correctly? – pHorseSpec Jul 14 '15 at 19:33
I've added some links answering how to perform a replacement on each line in a file in Python; they answer that question much better than I could. – DanielGibbs Jul 14 '15 at 19:55
This doesn't work, OP wants to both read and write the file from what I gather. – Nitesh Patel Jul 14 '15 at 20:12
The question answers why OP was getting the error message that they posted. I've added links to questions that answer how to read and perform replacements on each line in a file. – DanielGibbs Jul 14 '15 at 20:20

Joran Beasley · Answer 3 · 2015-07-14T19:24:49.007

1

fileinput will allow you to read/write to the same file pretty easily ...

with fileinput.input("out.txt") as fo:
     for line in file:
         print line.replace("(comma)"," , ")

edited Jul 14 '15 at 19:24

answered Jul 14 '15 at 19:19

Joran Beasley

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score 0 · Answer 4 · answered Jul 14 '15 at 19:12

0

Try opening the file in write mode:

with open('outputFile', 'w+') as fo:
    fo.write(line.replace("(comma)"," , "))

answered Jul 14 '15 at 19:12

Jules

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Replace Text with Comma in File With Python

4 Answers4