How to Properly Duplicate Dictionaries in Python and Avoid Modifying the Original?

Duplicating Dictionaries: Preserving Originality

When assigning one dictionary to another in Python, it's important to remember that references are created, not copies. This means that any changes made to the assigned dictionary (the copy) will also affect the original dictionary. To prevent this behavior, a true copy of the dictionary must be created.

Consider the following example:

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

After assigning dict2 to dict1, changes made to dict2 are reflected in dict1 as well. To avoid this, an explicit copy must be made:

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

Alternatively, copy() method can be used:

dict2 = dict1.copy()
dict2["key2"] = "WHY?!"
print(dict1)  # {'key2': 'value2', 'key1': 'value1'}

By using either of these methods, changes made to the copied dictionary (dict2) will not affect the original dictionary (dict1).

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