how to make a python dictionary

David Muir

2 min read

·

05-09-2024

47

0

Share

Creating a Python dictionary is like building a treasure chest where each item is stored with a unique label. In this article, we'll explore how to create and use dictionaries in Python, making it easy for you to store and access data effectively.

What is a Python Dictionary?

A Python dictionary is a collection of key-value pairs. Each key is unique and serves as an identifier for its associated value. Think of it as a real-world dictionary where you look up a word (the key) to find its definition (the value).

Key Features of Python Dictionaries

• Unordered: The items in a dictionary do not have a defined order.
• Mutable: You can change, add, or remove items after the dictionary is created.
• Indexed by keys: Values are accessed by their keys instead of numeric indices.

Creating a Python Dictionary

There are several ways to create a dictionary in Python. Let's explore a few of them.

1. Using Curly Braces

You can create a dictionary by enclosing key-value pairs in curly braces {}.

# Example of creating a dictionary using curly braces
my_dict = {
    "name": "Alice",
    "age": 30,
    "city": "New York"
}

print(my_dict)

2. Using the dict() Constructor

Another way to create a dictionary is by using the dict() constructor.

# Example of creating a dictionary using the dict() constructor
my_dict = dict(name="Bob", age=25, city="Los Angeles")

print(my_dict)

3. From a List of Tuples

You can also create a dictionary from a list of tuples, where each tuple contains a key-value pair.

# Example of creating a dictionary from a list of tuples
my_list_of_tuples = [("name", "Charlie"), ("age", 22), ("city", "Chicago")]
my_dict = dict(my_list_of_tuples)

print(my_dict)

Accessing Dictionary Values

Once you have a dictionary, accessing its values is straightforward. You can do this by using the keys.

# Accessing values in a dictionary
print(my_dict["name"])  # Output: Charlie
print(my_dict["age"])   # Output: 22

Using the .get() Method

You can also use the .get() method to access values, which allows you to specify a default value if the key does not exist.

# Using .get() method
print(my_dict.get("city", "Not Found"))  # Output: Chicago
print(my_dict.get("country", "Not Found"))  # Output: Not Found

Modifying a Dictionary

Dictionaries in Python are mutable, meaning you can easily change them.

Adding New Key-Value Pairs

You can add new items simply by assigning a value to a new key.

# Adding a new key-value pair
my_dict["country"] = "USA"
print(my_dict)

Updating Existing Values

If a key already exists, you can update its value.

# Updating an existing value
my_dict["age"] = 23
print(my_dict)

Removing Items

You can remove items using the del statement or the .pop() method.

# Removing an item using del
del my_dict["city"]
print(my_dict)

# Removing an item using .pop()
age = my_dict.pop("age")
print(my_dict)
print("Removed age:", age)

Conclusion

Python dictionaries are a powerful way to manage and organize data efficiently. Whether you’re building a complex application or just need to store some values temporarily, dictionaries are an excellent tool to have in your Python toolkit.

Additional Resources

• Python Official Documentation
• Learning Python Dictionaries - W3Schools

By mastering dictionaries, you'll be well on your way to writing more effective and organized Python code. Happy coding!