[python] 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?

This question is related to python

The answer is


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.


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


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