TypeError: 'list' object is not callable in python

Question

I am novice to Python and following a tutorial. There is an example of list in the tutorial :

example = list(\'easyhoss\')

Now

Answer 1

In the league of stupid Monday morning mistakes, using round brackets instead of square brackets when trying to access an item in the list will also give you the same error message:

l=[1,2,3]

print(l[2])#GOOD
print(l(2))#BAD

TypeError: 'list' object is not callable

Answer 2

I was getting this error for another reason:

I accidentally had a blank list created in my __init__ which had the same name as a method I was trying to call (I had just finished refactoring a bit and the variable was no longer needed, but I missed it when cleaning up). So when I was instantiating the class and trying to call the method, it thought I was referencing the list object, not the method:

class DumbMistake:
    def __init__(self, k, v):
        self.k = k
        self.v = v
        self.update = []

    def update(self):
        // do updates to k, v, etc

if __name__ == '__main__':
    DumbMistake().update('one,two,three', '1,2,3')

So it was trying to assign the two strings to self.update[] instead of calling the update() method. Removed the variable and it all worked as intended. Hope this helps someone.

Answer 3

Why does TypeError: 'list' object is not callable appear?

Explanation:

It is because you defined list as a variable before (i am pretty sure), so it would be a list, not the function anymore, that's why everyone shouldn't name variables functions, the below is the same as what you're doing now:

>>> [1,2,3]()
Traceback (most recent call last):
  File "<pyshell#0>", line 1, in <module>
    [1,2,3]()
TypeError: 'list' object is not callable
>>>  

So you need it to be the default function of list, how to detect if it is? just use:

>>> list
<class 'list'>
>>> list = [1,2,3]
>>> list
[1, 2, 3]
>>> list()
Traceback (most recent call last):
  File "<pyshell#4>", line 1, in <module>
    list()
TypeError: 'list' object is not callable
>>> 

How do i detect whether a variable name is a function? well, just simple see if it has a different color, or use a code like:

>>> 'list' in dir(__builtins__)
True
>>> 'blah' in dir(__builtins__)
False
>>> 

After this, you should know why does TypeError: 'list' object is not callable appear.

Okay, so now...

How to fix this TypeError: 'list' object is not callable error?

Code:

You have to either do __builtins__.list():

>>> list = [1,2,3]
>>> __builtins__.list()
[]
>>> 

Or use []:

>>> list = [1,2,3]
>>> []
[]
>>> 

Or remove list variable from memory:

>>> list = [1,2,3]
>>> del list
>>> list()
[]
>>> 

Or just rename the variable:

>>> lst = [1,2,3]
>>> list()
[]
>>> 

P.S. Last one is the most preferable i guess :-)

There are a whole bunch of solutions that work.

References:

'id' is a bad variable name in Python

How do I use a keyword as a variable name?

How to use reserved keyword as the name of variable in python?

Answer 4

Before you can fully understand what the error means and how to solve, it is important to understand what a built-in name is in Python.

What is a built-in name?

In Python, a built-in name is a name that the Python interpreter already has assigned a predefined value. The value can be either a function or class object. These names are always made available by default, no matter the scope. Some of the values assigned to these names represent fundamental types of the Python language, while others are simple useful.

As of the latest version of Python - 3.6.2 - there are currently 61 built-in names. A full list of the names and how they should be used, can be found in the documentation section Built-in Functions.

An important point to note however, is that Python will not stop you from re-assigning builtin names. Built-in names are not reserved, and Python allows them to be used as variable names as well.

Here is an example using the dict built-in:

>>> dict = {}
>>> dict
{}
>>>

As you can see, Python allowed us to assign the dict name, to reference a dictionary object.

What does "TypeError: 'list' object is not callable" mean?

To put it simply, the reason the error is occurring is because you re-assigned the builtin name list in the script:

list = [1, 2, 3, 4, 5]

When you did this, you overwrote the predefined value of the built-in name. This means you can no longer use the predefined value of list, which is a class object representing Python list.

Thus, when you tried to use the list class to create a new list from a range object:

myrange = list(range(1, 10))

Python raised an error. The reason the error says "'list' object is not callable", is because as said above, the name list was referring to a list object. So the above would be the equivalent of doing:

[1, 2, 3, 4, 5](range(1, 10))

Which of course makes no sense. You cannot call a list object.

How can I fix the error?

Suppose you have code such as the following:

list = [1, 2, 3, 4, 5]
myrange = list(range(1, 10))

for number in list:
    if number in myrange:
        print(number, 'is between 1 and 10')

Running the above code produces the following error:

Traceback (most recent call last):
  File "python", line 2, in <module>
TypeError: 'list' object is not callable

If you are getting a similar error such as the one above saying an "object is not callable", chances are you used a builtin name as a variable in your code. In this case and other cases the fix is as simple as renaming the offending variable. For example, to fix the above code, we could rename our list variable to ints:

ints = [1, 2, 3, 4, 5] # Rename "list" to "ints"
myrange = list(range(1, 10))

for number in ints: # Renamed "list" to "ints"
    if number in myrange:
        print(number, 'is between 1 and 10')

PEP8 - the official Python style guide - includes many recommendations on naming variables.

This is a very common error new and old Python users make. This is why it's important to always avoid using built-in names as variables such as str, dict, list, range, etc.

Many linters and IDEs will warn you when you attempt to use a built-in name as a variable. If your frequently make this mistake, it may be worth your time to invest in one of these programs.

I didn't rename a built-in name, but I'm still getting "TypeError: 'list' object is not callable". What gives?

Another common cause for the above error is attempting to index a list using parenthesis (()) rather than square brackets ([]). For example:

>>> lst = [1, 2]
>>> lst(0)

Traceback (most recent call last):
  File "<pyshell#32>", line 1, in <module>
    lst(0)
TypeError: 'list' object is not callable

For an explanation of the full problem and what can be done to fix it, see TypeError: 'list' object is not callable while trying to access a list.

Answer 5

You may have used built-in name 'list' for a variable in your code. If you are using Jupyter notebook, sometimes even if you change the name of that variable from 'list' to something different and rerun that cell, you may still get the error. In this case you need to restart the Kernal. In order to make sure that the name has change, click on the word 'list' when you are creating a list object and press Shift+Tab, and check if Docstring shows it as an empty list.