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

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?

Answer 1

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