Question

I found a strange thing in Python when I tried to compare lists composed of integers.

For example:

In [35]: id(range(1,5)),id(range(1,15)),id(range(16,0,-1))
Out[35]: (155687404, 155687404, 155687404)

Q1:
Why their id() values are the same? And how can they be the same since they look different?

Q2:
How can I compare lists of integers by id() values?

Q3:
To be more inquisitive, how is the id() value computed in Python?

Answer 1

Directly from python’s doc:

Return the “identity” of an object. This is an integer (or long integer) 
which is guaranteed to be unique and constant for this object during its lifetime. 
Two objects with non-overlapping lifetimes may have the same id() value.

You could get the md5 hash to compare theese objects:

import md5
>>> md5.new(str(range(1,5))).hexdigest()
'd5397571a7f9c05bd58bed77f9dbe8f0'
>>> md5.new(str(range(1,15))).hexdigest()
'000b3ca7f2653a13cdb5b96f21c2ba4d'