Python Add to Dictionary Without Overwriting

Dictionaries in Python are versatile data structures that allow you to store and manage key-value pairs. One common challenge when working with dictionaries is how to add new key-value pairs without overwriting existing ones. In this article, we’ll explore five simple and commonly used methods to achieve this in Python

Python Add to Dictionary Without Overwriting

Below, are the examples of how to Python add to Dictionary Without Overwriting.

• Assignment Method
• Using update() Method
• Using setdefault() Method
• Using ** Unpacking Operator

Add to Dictionary using Assignment

In this example, the below code creates a dictionary `existing_dict` with ‘name’ and ‘age’ keys. It then adds ‘city: New York’ and updates ‘age’ to 26. The final dictionary is printed, showing the changes.

Python3

existing_dict = {'name': 'John', 'age': 25}

# Adding a new key-value pair or updating an existing one
existing_dict['city'] = 'New York'
existing_dict['age'] = 26

print(existing_dict)

Output

{'name': 'John', 'age': 26, 'city': 'New York'}

Using update() Method

In this example, below code combines two dictionaries, `existing_dict` and `new_data`, using the `update()` method. It updates existing keys and adds new ones, resulting in a modified dictionary that is then printed.

Python3

existing_dict = {'name': 'John', 'age': 25}
new_data = {'city': 'New York', 'age': 26}

existing_dict.update(new_data)

print(existing_dict)

Output

{'name': 'John', 'age': 26, 'city': 'New York'}

Using setdefault() Method

In this example , below code uses `setdefault()` to add ‘city: New York’ to the dictionary `existing_dict` only if ‘city’ is not already a key. It also attempts to set the ‘age’ key to 26, but this has no effect as the key already exists.

Python3

existing_dict = {'name': 'John', 'age': 25}

existing_dict.setdefault('city', 'New York')
existing_dict.setdefault('age', 26)

print(existing_dict)

Output

{'name': 'John', 'age': 25, 'city': 'New York'}

Using ** Unpacking Operator

In this example, below code merges two dictionaries, `existing_dict` and `new_data`, using the `**` unpacking operator. It creates a new dictionary `merged_dict` containing the combined key-value pairs. The resulting dictionary is then printed, illustrating the merged data.

Python3

existing_dict = {'name': 'John', 'age': 25}
new_data = {'city': 'New York', 'age': 26}

merged_dict = {**existing_dict, **new_data}

print(merged_dict)

Output

{'name': 'John', 'age': 26, 'city': 'New York'}

Conclusion

In conclusion above, methods provide simple and effective ways to add key-value pairs to a dictionary in Python without overwriting existing entries. Depending on your specific use case, you can choose the method that best fits your needs. Whether it’s using update(), setdefault(), dict.update(), the ** unpacking operator, Python offers multiple approaches to handle dictionary updates efficiently.