TypeError: "NoneType" object is unsubscriptable

Question

I have this error when running this code with Python:

TypeError: "NoneType" object is unsubscriptable".

Code:

number = 0

with open('playlist.txt') as read_number_lines:
    for line in read_number_lines:
        if line.strip():
            number += 1

number = number - 1
print 'number: ', number

for i in range(number):
    author_ = raw_input('author: ')
    line = input('line: ')
    file = open('playlist.txt','a').writelines(' - ' + author_)[line]

How do I fix it?

`writelines(' - ' + author_)[line]` what are you trying to do here? — Ashwini Chaudhary, Aug 03 '13 at 19:56
Write the author at the specific line, next to the song's title. — Black_Ram, Aug 03 '13 at 19:59
Post your expected output, you just can't write at any line number you want using `file.writelines`. — Ashwini Chaudhary, Aug 03 '13 at 20:02
For the line count: [How to get line count cheaply in Python?](http://stackoverflow.com/questions/845058/how-to-get-line-count-cheaply-in-python) — Ashwini Chaudhary, Aug 03 '13 at 20:05

score 1 · Answer 1 · answered Aug 03 '13 at 19:58

1

You've got a few problems in

file = open('playlist.txt','a').writelines(' - ' + author_)[line]

The immediate source of your error is that .writelines() doesn't return anything (so it returns None) which you're trying to index using [line]. That produces your error.

Also, you shouldn't be calling that method on the open() call directly.

The entire second for loop is mysterious to me. You're opening that file again during each iteration of the loop (which you don't want to do; it probably wouldn't even work).

Perhaps you wanted to do something like

with open('playlist.txt','a') as file:
    for i in range(number):
        author_ = raw_input('author: ')
        line = raw_input('line: ')
        file.write(author + " - " + line)

but it's still hard to see the point of this...

answered Aug 03 '13 at 19:58

Tim Pietzcker

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I think `line` is the line number at which OP is trying to write the content. – Ashwini Chaudhary Aug 03 '13 at 20:04
The variable 'line' is an integer that I use for link the write's line. Author will be the string written in line selected by me. :) – Black_Ram Aug 03 '13 at 20:32
You can't index a file like this. You should read the file into a list (using `.readlines()`) and work on that list, then write the whole list back to a new file using `.writelines()`. But that's out of the scope of this question. – Tim Pietzcker Aug 03 '13 at 20:35
Tim, an example for this? – Black_Ram Aug 03 '13 at 20:53
You should open a new question for this. – Tim Pietzcker Aug 03 '13 at 20:58

TypeError: "NoneType" object is unsubscriptable

1 Answers1