In python, when assigning one array to another, they are equal, how to make them independent?

Question

Python

>>> b = [1,2]
>>> a = b
>>> a[0]+=1
>>> print(a[0])
2
>>> print(b[0])
2
It was a discovery for me. How to make copied array independent?

Answer 1

the easiest

a = b[:]
# или
a = b.copy()

but this won't help if the list is part of itself:

b = [1, 2]
>>> b.append(b)
>>> b
[1, 2, [...]]
>>> id(b)
139920848119752
>>> id(b[2])
139920848119752
>>> a = b[:]
>>> a
[1, 2, [1, 2, [...]]]
>>> id(a)
139920848120456
>>> id(a[2])
139920848119752

but deepcopy will already cope with this

from copy import deepcopy
>>> a = deepcopy(b)
>>> a
[1, 2, [...]]
>>> id(a)
139920847744840
>>> id(a[2])
139920847744840