Python dict.copy Usage Detailed Explanation and Examples

dict.copy() is a method used to copy dictionaries in Python. It takes no parameters and is simply called with . after the dictionary object.

Below are three examples using dict.copy():

1. Copying a dictionary:

person = {"name": "Tom", "age": 20, "city": "New York"}
person_copy = person.copy()
print(person_copy) # Output: {"name": "Tom", "age": 20, "city": "New York"}

In this example, we define a dictionary named person and then use the person.copy() method to copy it to person_copy. This creates a new dictionary named person_copy, and the two dictionaries are completely independent and do not affect each other.

2. Avoid changes in the original dictionary from affecting the copy:

person = {"name": "Tom", "age": 20, "city": "New York"}
person_copy = person.copy()
person["name"] = "John"
print(person) # Output: {"name": "John", "age": 20, "city": "New York"}
print(person_copy) # Output: {"name": "Tom", "age": 20, "city": "New York"}

In this example, we modify the value of the original dictionary person, but the value of the copy dictionary person_copy remains unchanged, indicating that there is no association between them.

3. Copying nested dictionaries:

person = {"name": "Tom", "age": 20, "address": {"city": "New York", "zipcode": 12345}}
person_copy = person.copy()
person["address"]["city"] = "London"
print(person) # Output: {"name": "Tom", "age": 20, "address": {"city": "London", "zipcode": 12345}}
print(person_copy) # Output: {"name": "Tom", "age": 20, "address": {"city": "London", "zipcode": 12345}}

In this example, we can see that dict.copy() can be used even with nested dictionaries. However, it’s important to note that nested dictionary copies are still shallow copies, meaning that the objects in the nested dictionary remain the same, and modifying the values in one dictionary will affect the same location in the other dictionary.

The above is the usage of dict.copy() and three examples. dict.copy() allows you to conveniently create a copy of the original dictionary, and modifying the values in the original dictionary will not affect the copy.