🚀 Shallow Copy vs Deep Copy in Python

When copying objects in Python, behavior changes for nested data structures.


📌 Shallow Copy

A shallow copy creates a new outer object 
but inner objects remain shared references 🔗 

import copy

original = [[1, 2], [3, 4]]
shallow = copy.copy(original)

shallow[0].append(99)

print(original)
print(shallow)

Output:
[[1, 2, 99], [3, 4]]
[[1, 2, 99], [3, 4]]

👉 Nested objects are shared.


📌 Deep Copy

A deep copy creates a completely independent copy 
including all nested objects 🧠 

import copy

original = [[1, 2], [3, 4]]
deep = copy.deepcopy(original)

deep[0].append(99)

print(original)
print(deep)

Output:
[[1, 2], [3, 4]]
[[1, 2, 99], [3, 4]]

👉 No shared references.


🎯 Quick Difference

• Shallow → Copies outer layer only 
• Deep → Copies entire structure 
• Use deep copy for nested data