What is the difference between a shallow copy and a deep copy of a nested list in Python?
Ava W

In Python, when you want to create a copy of a nested list, you have the option to make either a shallow copy or a deep copy. Understanding the difference between these two types of copies is crucial as it affects how changes to the original list or the copied list are reflected. 1. Shallow Copy: A shallow copy of a nested list creates a new list object but still references the same nested objects as the original list. In other words, the outer list is duplicated, but the inner objects are not. Both the original list and the shallow copy contain references to the same inner objects. Consequently, changes made to the inner objects are reflected in both the original list and the shallow copy. Here's an example of a shallow copy of a nested list:

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import copy

original_list = [[1, 2], [3, 4]]
shallow_copy = copy.copy(original_list)

shallow_copy[0].append(5)

print(original_list)  # Output: [[1, 2, 5], [3, 4]]
print(shallow_copy)  # Output: [[1, 2, 5], [3, 4]]

In the above code,original_list is the original nested list, andshallow_copy is created using thecopy.copy() function. Modifying the inner object ([1, 2]) of theshallow_copy list affects both theshallow_copy list and theoriginal_list. 2. Deep Copy: A deep copy of a nested list creates a completely independent copy of both the outer list and the inner objects. It creates a new list object with duplicated inner objects. Consequently, changes made to the inner objects in one list are not reflected in the other. Here's an example of a deep copy of a nested list:

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import copy

original_list = [[1, 2], [3, 4]]
deep_copy = copy.deepcopy(original_list)

deep_copy[0].append(5)

print(original_list)  # Output: [[1, 2], [3, 4]]
print(deep_copy)  # Output: [[1, 2, 5], [3, 4]]

In the above code, thedeepcopy() function from thecopy module is used to create a deep copy of theoriginal_list. Modifying the inner object ([1, 2]) of thedeep_copy list does not affect theoriginal_list. To summarize, the key differences between a shallow copy and a deep copy of a nested list in Python are: - Shallow copy creates a new list object that references the same nested objects as the original list, while deep copy creates a completely independent copy with duplicated inner objects. - Changes made to the inner objects in a shallow copy are reflected in the original list, while changes in a deep copy do not affect the original list. - Shallow copy is created using thecopy.copy() function, while deep copy is created using thecopy.deepcopy() function from thecopy module. Understanding these differences will help you choose the appropriate copy method for your nested lists based on your requirements.

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