CODEWITHSUNDEEP
python
mavix
mavix

Reputation: 2552

Python: TypeError: object of type 'NoneType' has no len()

I am getting an error from this Python code:

with open('names') as f:
    names = f.read()
    names = names.split('\n')
    names.pop(len(names) - 1)
    names = shuffle(names)
    f.close()

assert len(names) > 100

Error:

Python: TypeError: object of type 'NoneType' has no len()

The assert statement is throwing this error, what am I doing wrong?

Upvotes: 19

Views: 185353

Answers (4)

Rakesh Dangi
Rakesh Dangi

Reputation: 11

I was faces this issue but after change object into str, problem solved. str(fname).isalpha():

Upvotes: 0

Levon
Levon

Reputation: 143037

What is the purpose of this

 names = list;

? Also, no ; required in Python.

Do you want

 names = []

or 

 names = list()

at the start of your program instead? Though given your particular code, there's no need for this statement to create this names variable since you do so later when you read data into it from your file.

@JBernardo has already pointed out the other (and more major) problem with the code.

Upvotes: 3

John La Rooy
John La Rooy

Reputation: 304137

You don't need to assign names to list or [] or anything else until you wish to use it.

It's neater to use a list comprehension to make the list of names.

shuffle modifies the list you pass to it. It always returns None

If you are using a context manager (with ...) you don't need to close the file explicitly

from random import shuffle

with open('names') as f:
    names = [name.rstrip() for name in f if not name.isspace()]
    shuffle(names)

assert len(names) > 100

Upvotes: 5

JBernardo
JBernardo

Reputation: 33387

shuffle(names) is an in-place operation. Drop the assignment.

This function returns None and that's why you have the error: 

TypeError: object of type 'NoneType' has no len()

Upvotes: 28

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