What is the difference between a shallow copy and a deep copy?

Question

ICSM Computer · Answer

Shallow Copy
Creates a new object, but the contents (elements or references inside the object) are not copied recursively.The new object’s fields reference the same nested objects as the original.So changes to nested mutable objects inside either the original or the copy 
will affect both.
Example:
import copy
original = [1, 2, [3, 4]]
shallow = copy.copy(original)
shallow[2][0] = 'changed'
print(original)  # Output: [1, 2, ['changed', 4]]
Notice how modifying the nested list inside shallow also changed it in
original.
Deep Copy
Creates a new object and recursively copies all objects found inside it.The copy is completely independent of the original.Changes to any part of the copy won’t affect the original.
Example:
import copy
original = [1, 2, [3, 4]]
deep = copy.deepcopy(original)
deep[2][0] = 'changed'
print(original)  # Output: [1, 2, [3, 4]]
Here, the nested list inside deep is a completely separate copy, so modifying it does not change
original.
Summary:
Feature
Shallow Copy
Deep Copy
Copies object
Yes
Yes
Copies nested objects
No (references shared)
Yes (recursively copies nested objs)
Changes to nested mutable objects
Reflect in both copies
Independent
Use case
When nested objects are immutable or shared intentionally
When you need fully independent copy

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What is the difference between a shallow copy and a deep copy?

ICSM Computer

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1 Answers

Shallow Copy

Deep Copy

Summary:

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Feature	Shallow Copy	Deep Copy
Copies object	Yes	Yes
Copies nested objects	No (references shared)	Yes (recursively copies nested objs)
Changes to nested mutable objects	Reflect in both copies	Independent
Use case	When nested objects are immutable or shared intentionally	When you need fully independent copy