Why does the 'int' object is not callable error occur when using the sum() function?

Question

I'm trying to figure out why I'm getting an error when using the sum function on a range.

Here is the code:

data1 = range(0, 1000, 3)
data2 = range(0, 1000, 5)
data3 = list(set(data1 + data2)) # makes new list without duplicates
total = sum(data3) # calculate sum of data3 list's elements
print total

And here is the error:

line 8, in <module> total2 = sum(data3)
TypeError: 'int' object is not callable

I found this explanation for the error:

In Python a "callable" is usually a function. The message means you are treating a number (an >"int") as if it were a function (a "callable"), so Python doesn't know what to do, so it >stops.

I've also read that sum() is capable of being used on lists, so I'm wondering what is going wrong here?

I just tried it in an IDLE module and it worked fine. However, it doesn't work in the python interpreter. Any ideas on how that can be?

This works perfectly for me... did you name a variable `sum` before calling the function? — jadkik94, Jun 26 '12 at 06:32
Just edited original. I'm using IDE. Works in IDLE, as you mentioned. IDE is running Python 2.7. This is weird. — mattste, Jun 26 '12 at 06:37
An interactive editor for Python. http://code.google.com/p/iep/ — mattste, Jun 26 '12 at 06:40
You don't really need to convert your set back to a list... `sum()` will handle any sequence of numbers. — mhawke, Jun 26 '12 at 06:43

score 22 · Accepted Answer · edited May 12 '15 at 00:26

You probably redefined your "sum" function to be an integer data type. So it is rightly telling you that an integer is not something you can pass a range.

To fix this, restart your interpreter.

Python 2.7.3 (default, Apr 20 2012, 22:44:07) 
[GCC 4.6.3] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> data1 = range(0, 1000, 3)
>>> data2 = range(0, 1000, 5)
>>> data3 = list(set(data1 + data2)) # makes new list without duplicates
>>> total = sum(data3) # calculate sum of data3 list's elements
>>> print total
233168

If you shadow the sum builtin, you can get the error you are seeing

>>> sum = 0
>>> total = sum(data3) # calculate sum of data3 list's elements
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'int' object is not callable

Also, note that sum will work fine on the set there is no need to convert it to a list

score 21 · Answer 2 · answered Jun 26 '12 at 06:31

21

This means that somewhere else in your code, you have something like:

sum = 0

Which shadows the builtin sum (which is callable) with an int (which isn't).

answered Jun 26 '12 at 06:31

lvc

34,233
10
73
98

The code shown is the whole program. I wish it was that simple. Any other ideas? – mattste Jun 26 '12 at 06:33
2

@mattste restart your python interpreter and try it. – jamylak Jun 26 '12 at 06:37

score 3 · Answer 3 · answered Jun 26 '12 at 06:52

In the interpreter its easy to restart it and fix such problems. If you don't want to restart the interpreter, there is another way to fix it:

Python 2.6.6 (r266:84292, Dec 27 2010, 00:02:40)
[GCC 4.4.5] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> l = [1,2,3]
>>> sum(l)
6
>>> sum = 0 # oops! shadowed a builtin!
>>> sum(l)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'int' object is not callable
>>> import sys
>>> sum = sys.modules['__builtin__'].sum # -- fixing sum
>>> sum(l)
6

This also comes in handy if you happened to assign a value to any other builtin, like dict or list

Why does the 'int' object is not callable error occur when using the sum() function?

3 Answers3

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