id(object)
Returns unique identity ( integer or long integer ) of the python object.
id is assigned when object is created.
It is the address of the object's memory
id changes each time the program is run except some objects for which id is fexed.
Using integer
my_int=34
print(id(my_int)) # 10969856
Using list
my_list=[1,2,3]
print(id(my_list)) #139787163392648
Fixed id
These ids will remain same even after re-run of the program.
my_int=-5
print(id(my_int)) # 10968608
my_int=256
print(id(my_int)) # 10976960
my_int=257
Integer from -5 to 256, ids will not change.
Mutable and immutable object and id()
We can see for mutable objects by changing the element the ID will not change , whereas for immutable objects id will change.
More on Mutable & Immutable objects
List is a mutable object but tuple is a immutable object. Check how the identities are changing after adding elements.
Using tuple
my_tuple=(5,7,5,4,3,5)
print(id(my_tuple)) # 139787173397704
my_tuple +=(9,8)
print(id(my_tuple)) # 139787174601112
print(my_tuple) #(5, 7, 5, 4, 3, 5, 9, 8)
Using List
my_list=[5,7,5,4,3,5]
print(id(my_list)) # 139787163608584
my_list +=[9,8]
print(id(my_list)) # 139787163608584
print(my_list) # [5, 7, 5, 4, 3, 5, 9, 8]
Two non-overlapping lifetime objects may have the same identity or id() vlaue.
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