How to copy a dictionary and edit the copy only in Python

To copy a dictionary and edit the copy without affecting the original dictionary, you can use the copy() method provided by dictionaries or the copy module's deepcopy() function. The copy() method creates a shallow copy, while deepcopy() creates a deep copy.

Shallow copy using the copy() method:

A shallow copy creates a new dictionary but does not create new copies of the objects inside the dictionary. Instead, it refers to the same objects as the original dictionary. This is suitable when the dictionary contains only immutable objects (like numbers, strings, or tuples) or when you don't plan to modify any nested dictionaries or lists.

original_dict = {'a': 1, 'b': 2, 'c': 3}

# Create a shallow copy of the original dictionary
copied_dict = original_dict.copy()

# Edit the copied dictionary
copied_dict['d'] = 4

# Print both dictionaries
print("Original dictionary:", original_dict)
print("Copied dictionary:", copied_dict)

Output:

Original dictionary: {'a': 1, 'b': 2, 'c': 3}
Copied dictionary: {'a': 1, 'b': 2, 'c': 3, 'd': 4}

Deep copy using the deepcopy() function:

A deep copy creates a new dictionary and new copies of all objects inside the dictionary, recursively. This is suitable when the dictionary contains mutable objects (like lists or other dictionaries) and you want to modify these nested objects without affecting the original dictionary.

from copy import deepcopy

original_dict = {'a': 1, 'b': 2, 'c': [3, 4]}

# Create a deep copy of the original dictionary
copied_dict = deepcopy(original_dict)

# Edit the copied dictionary and its nested list
copied_dict['c'].append(5)

# Print both dictionaries
print("Original dictionary:", original_dict)
print("Copied dictionary:", copied_dict)

Output:

Original dictionary: {'a': 1, 'b': 2, 'c': [3, 4]}
Copied dictionary: {'a': 1, 'b': 2, 'c': [3, 4, 5]}

In this example, using a deep copy ensures that the nested list inside the dictionary is also copied, so modifying it in the copied dictionary does not affect the original dictionary.

Python copy dictionary and modify copy:

original_dict = {'a': 1, 'b': 2}
copied_dict = original_dict.copy()
copied_dict['a'] = 100
print(original_dict)
print(copied_dict)

Copy and update dictionary in Python:

original_dict = {'a': 1, 'b': 2}
updated_dict = original_dict.copy()
updated_dict.update({'a': 100, 'c': 3})
print(original_dict)
print(updated_dict)

Python dictionary deepcopy for editing copy:

from copy import deepcopy

original_dict = {'a': {'x': 1, 'y': 2}, 'b': 3}
copied_dict = deepcopy(original_dict)
copied_dict['a']['x'] = 100
print(original_dict)
print(copied_dict)

Edit copied dictionary without affecting the original using copy module:

import copy

original_dict = {'a': 1, 'b': 2}
copied_dict = copy.copy(original_dict)
copied_dict['a'] = 100
print(original_dict)
print(copied_dict)

Python dict() constructor for copying and modifying dictionaries:

original_dict = {'a': 1, 'b': 2}
copied_dict = dict(original_dict)
copied_dict['a'] = 100
print(original_dict)
print(copied_dict)

Copying and updating dictionary in a single step in Python:

original_dict = {'a': 1, 'b': 2}
updated_dict = dict(original_dict, a=100, c=3)
print(original_dict)
print(updated_dict)

Edit a dictionary copy using dictionary comprehension in Python:

original_dict = {'a': 1, 'b': 2}
copied_dict = {key: value * 2 for key, value in original_dict.items()}
print(original_dict)
print(copied_dict)

Clone and modify dictionary entries in Python:

original_dict = {'a': 1, 'b': 2}
copied_dict = original_dict.copy()
copied_dict.update((key, value * 2) for key, value in original_dict.items())
print(original_dict)
print(copied_dict)

Create a new dictionary by modifying an existing one in Python:

original_dict = {'a': 1, 'b': 2}
modified_dict = {key: value * 2 for key, value in original_dict.items()}
print(original_dict)
print(modified_dict)

Copy dictionary and modify values with iteration in Python:

original_dict = {'a': 1, 'b': 2}
copied_dict = {key: value + 10 for key, value in original_dict.items()}
print(original_dict)
print(copied_dict)

Update specific keys in a copied dictionary in Python:

original_dict = {'a': 1, 'b': 2, 'c': 3}
keys_to_update = {'a', 'c'}
copied_dict = {key: original_dict[key] * 2 if key in keys_to_update else original_dict[key] for key in original_dict}
print(original_dict)
print(copied_dict)

Perform in-place modifications on a copied dictionary in Python:

original_dict = {'a': 1, 'b': 2}
copied_dict = original_dict.copy()
for key in copied_dict:
    copied_dict[key] += 10
print(original_dict)
print(copied_dict)