Why is single int 24 bytes, but in list it tends to 8 bytes

Question

Here is what I am looking at:

In [1]: import sys

In [2]: sys.getsizeof(45)
Out[2]: 24

In [3]: sys.getsizeof([])
Out[3]: 72

In [4]: sys.getsizeof(range(1000))
Out[4]: 8072

I know that int in Python is growable (can get bigger that 24 bytes) objects that live on the heap, and I see why that object can be quite large, but isn't a list just a collections of such objects? Apparently it is not, what is going on here?

Answer 1

This is the size of the object - excluding the objects it contains:

>>> d = range(10)
>>> sys.getsizeof(d)
152
>>> d[0] = 'text'
>>> sys.getsizeof(d)
152
>>> d
['text', 1, 2, 3, 4, 5, 6, 7, 8, 9]

The size of the list with 1000 elements, in your case, is 8072 bytes but each integer object is still 24 bytes. The list object keeps track of these integer objects but they're not included in the size of the list object.