What is the difference between deep copy and shallow copy in Python?

What is the difference between deep copy and shallow copy in Python?

In Python, a shallow copy creates a new object but inserts references into it to the objects found in the original. A deep copy creates a new object and recursively adds copies of nested objects found in the original.

Can you give me an example of each?

Sure! For a shallow copy, you can use the copy module's copy() function. For a deep copy, use copy.deepcopy(). Here's a quick example:

import copy

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

original[2][0] = 'Changed'

print(shallow)  # Output: [1, 2, ['Changed', 4]]
print(deep)     # Output: [1, 2, [3, 4]]

What happens if I modify the original object after copying?

If you modify the original object after creating a shallow copy, the changes will reflect in the shallow copy for nested objects. However, a deep copy will remain unchanged because it has its own copies of the nested objects.

Are there any performance implications between the two?

Yes, deep copying can be more resource-intensive and slower than shallow copying, especially for large objects with many nested elements, because it creates copies of all nested objects.