*Memos:
- My post explains an iterator (1).
- My post explains the shallow and deep copy of a list.
- My post explains the shallow and deep copy of a tuple.
- My post explains the shallow copy of the set with a tuple.
- My post explains the shallow and deep copy of the set with an iterator.
- My post explains the shallow and deep copy of a dictionary.
- My post explains variable assignment.
Normal Copy:
*Memos:
-
v1andv2refer to the same shallow and deep iterator. -
iskeyword can check ifv1andv2refer to the same iterator.
# Shallow iterator
# ↓↓↓↓↓↓ ↓↓
v1 = iter([iter(['a'])])
v2 = v1 # ↑↑↑↑↑↑↑↑↑↑↑
# Deep iterator
print(v1) # <list_iterator object at 0x0000029DDFFB7D30>
print(v2) # <list_iterator object at 0x0000029DDFFB7D30>
print(v1 is v2) # True
print(next(v1)) # <list_iterator object at 0x0000029DDEC54E50>
print(next(v2)) # StopIteration:
Shallow Copy:
copy() can do shallow copy as shown below:
*Memos:
-
v1andv2refer to different shallow iterators. -
v1andv2refer to the same deep iterator.
from copy import copy
v1 = iter([iter(['a'])])
v2 = copy(v1) # Here
print(v1) # <list_iterator object at 0x0000029DE015CDC0>
print(v2) # <list_iterator object at 0x0000029DE015F340>
print(v1 is v2) # False
v3 = next(v1)
v4 = next(v2)
print(v3) # <list_iterator object at 0x0000029DD4BF82E0>
print(v4) # <list_iterator object at 0x0000029DD4BF82E0>
print(v3 is v4) # True
print(next(v3)) # a
print(next(v4)) # StopIteration:
Deep Copy:
deepcopy() can do deep copy as shown below:
*Memos:
-
v1andv2refer to the different shallow and deep iterators. -
deepcopy()should be used because it's safe, doing copy deeply.
from copy import deepcopy
v1 = iter([iter(['a'])])
v2 = deepcopy(v1) # Here
print(v1) # <list_iterator object at 0x0000029DDF283E80>
print(v2) # <list_iterator object at 0x0000029DDF282080>
print(v1 is v2) # False
v3 = next(v1)
v4 = next(v2)
print(v3) # <list_iterator object at 0x0000029DDF279D50>
print(v4) # <list_iterator object at 0x0000029DDF283FA0>
print(v3 is v4) # False
print(next(v3)) # a
print(next(v4)) # a
The below with copy() which can do shallow copy is equivalent to the above:
from copy import copy
v1 = iter([iter(['a'])])
v2 = copy(v1) # Here
print(v1) # <list_iterator object at 0x0000029DDFF4D7E0>
print(v2) # <list_iterator object at 0x0000029DDFF4D2D0>
print(v1 is v2) # False
v3 = copy(next(v1)) # Here
v4 = copy(next(v2)) # Here
print(v3) # <list_iterator object at 0x0000029DDFF4CEE0>
print(v4) # <list_iterator object at 0x0000029DDF283E80>
print(v3 is v4) # False
print(next(v3)) # a
print(next(v4)) # a
Additionally, the below is a 3D iterator:
from copy import deepcopy
v1 = iter([iter([iter(['a'])])])
v2 = deepcopy(v1) # Here
print(v1) # <list_iterator object at 0x0000029DDF281EA0>
print(v2) # <list_iterator object at 0x0000029DDEAECB20>
print(v1 is v2) # False
v3 = next(v1)
v4 = next(v2)
print(v3) # <list_iterator object at 0x0000029DDF282FE0>
print(v4) # <list_iterator object at 0x0000029DDFF4F760>
print(v3 is v4) # False
v5 = next(v3)
v6 = next(v4)
print(v5) # <list_iterator object at 0x0000029DDEECEA40>
print(v6) # <list_iterator object at 0x0000029DDFF4FAC0>
print(v5 is v6) # False
print(next(v5)) # a
print(next(v6)) # a