How to Create True Copies of Python Dictionaries?

Preserving Original Dictionaries: Separating Copies from Origin

When working with Python dictionaries, it's crucial to understand that assignment doesn't create copies. Assigning one dictionary to another, as in dict2 = dict1, establishes both variables as references pointing to the same dictionary object. Consequently, modifications to either dictionary affect both.

The Solution: Explicit Copying

To avoid this behavior and preserve the original dictionary, explicit copying is necessary. Python offers two methods for achieving this:

Method 1: Using dict(dict1)

dict2 = dict(dict1)

This method creates a new dictionary that is an exact copy of dict1.

Method 2: Using dict1.copy()

dict2 = dict1.copy()

This method also generates a new dictionary that is a duplicate of dict1.

Demonstration

To illustrate the difference between reference and copy, consider the following example:

dict1 = {"key1": "value1", "key2": "value2"}

# Copy dict1 using dict(dict1)
dict2 = dict(dict1)
dict2["key2"] = "WHY?!"
print(dict1)  # Output: {'key1': 'value1', 'key2': 'value2'}

# Copy dict1 using dict1.copy()
dict3 = dict1.copy()
dict3["key2"] = "CHANGED!"
print(dict1)  # Output: {'key1': 'value1', 'key2': 'value2'}

In this example, dict2 and dict3 refer to separate dictionaries. Modifying either copy doesn't affect the original dictionary dict1.

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