id
β’ 103 words β’ 1 min β’ updated
Identity function:
python
>>> help(id)
Help on built-in function id in module builtins:
id(obj, /)
Return the identity of an object.
This is guaranteed to be unique among simultaneously existing objects.
(CPython uses the object's memory address.)Different values have distinct IDs:
python
>>> id(1)
4314997520
>>> id(2)
4314997552Beware of mutable objects:
python
>>> id(set())
4318516320
>>> id(set())
4318519232Same ID in this case:
python
>>> a = set()
>>> b = a
>>> assert id(a) == id(b)Do not confound id() with lambda x: x. This is also an identity function,
but in the mathematical sense in that f(x) = x.