Immutable vs Mutable types

Question

I\'m confused on what an immutable type is. I know the float object is considered to be immutable, with this type of example from my book:

class         


        

Answer 1

Common immutable type:

1. numbers: int(), float(), complex()
2. immutable sequences: str(), tuple(), frozenset(), bytes()

Common mutable type (almost everything else):

1. mutable sequences: list(), bytearray()
2. set type: set()
3. mapping type: dict()
4. classes, class instances
5. etc.

One trick to quickly test if a type is mutable or not, is to use id() built-in function.

Examples, using on integer,

>>> i = 1
>>> id(i)
***704
>>> i += 1
>>> i
2
>>> id(i)
***736 (different from ***704)

using on list,

>>> a = [1]
>>> id(a)
***416
>>> a.append(2)
>>> a
[1, 2]
>>> id(a)
***416 (same with the above id)