Python | Ways to Copy Dictionary

Python | Ways to Copy Dictionary

In Python, you can copy a dictionary in several ways, depending on whether you want a shallow copy (where the top-level container is duplicated, but the copies refer to the same objects as the sources) or a deep copy (where all the contents are duplicated as well). Here are some common methods:

Shallow Copy

Using the dict Constructor

You can pass the original dictionary to the dict constructor to create a shallow copy:

original = {'a': 1, 'b': [2, 3, 4]} shallow_copy = dict(original)

Using the .copy() Method

Dictionaries have a .copy() method which returns a shallow copy:

shallow_copy = original.copy()

Using Dictionary Comprehension

You can also use dictionary comprehension to make a shallow copy:

shallow_copy = {key: value for key, value in original.items()}

Using the copy Module

The copy module's copy() function also creates shallow copies:

import copy shallow_copy = copy.copy(original)

Deep Copy

Using the copy Module's deepcopy()

If your dictionary contains complex objects, like other dictionaries, lists, or custom objects, and you want to copy those as well, you'll need to make a deep copy:

import copy deep_copy = copy.deepcopy(original)

The deepcopy() function will recursively copy all objects contained in the original dictionary, so that the copy is independent of the original.

When to Use Each Method

  • Shallow Copy: Use a shallow copy if the dictionary contains only immutable values (e.g., numbers, strings, tuples) or if you intend to change only the top-level elements.
  • Deep Copy: Use a deep copy if the dictionary contains mutable objects that you want to duplicate so that changes in the copy do not affect the original dictionary.

It's important to choose the correct type of copy based on your use case to avoid unintended side effects.

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