Python Tutorial for Beginners 5: Dictionaries - Working with Key-Value Pairs

Introduction

In this tutorial, we will explore Python dictionaries, a powerful data structure that allows you to store and manipulate data using key-value pairs. Understanding how to work with dictionaries is essential for beginners, as they are widely used in Python programming for various applications, including data management and retrieval.

Step 1: Creating a Dictionary

To start using dictionaries in Python, you need to create one. Here’s how:

• Use curly braces {} to define a dictionary.
• Specify key-value pairs separated by a colon :.

Example

my_dict = {
    "name": "Alice",
    "age": 30,
    "city": "New York"
}

Step 2: Accessing Values

You can access the values in a dictionary by using their corresponding keys.

• Use square brackets [] with the key name to retrieve the value.

Example

print(my_dict["name"])  # Output: Alice

Step 3: Adding Key-Value Pairs

To add a new key-value pair to an existing dictionary:

• Assign a value to a new key.

Example

my_dict["job"] = "Engineer"

Step 4: Removing Key-Value Pairs

You can remove a key-value pair from a dictionary using the del statement or the pop() method.

• Using del:

del my_dict["age"]

• Using pop():

job = my_dict.pop("job")

Step 5: Looping Through Dictionaries

You can loop through a dictionary to access keys, values, or both.

Looping Through Keys

for key in my_dict:
    print(key)

Looping Through Values

for value in my_dict.values():
    print(value)

Looping Through Key-Value Pairs

for key, value in my_dict.items():
    print(key, value)

Step 6: Dictionary Methods

Familiarize yourself with some common dictionary methods:

• my_dict.keys(): Returns a view object displaying a list of all keys.
• my_dict.values(): Returns a view object displaying a list of all values.
• my_dict.items(): Returns a view object displaying a list of key-value pairs.

Example

print(my_dict.keys())   # Output: dict_keys(['name', 'city'])
print(my_dict.values()) # Output: dict_values(['Alice', 'New York'])

Conclusion

In this tutorial, we covered the basics of Python dictionaries, including how to create them, access and modify key-value pairs, and loop through their contents. Understanding dictionaries is crucial for effective data handling in Python.

Next steps could include exploring nested dictionaries and combining them with other data structures for more complex data management tasks. Happy coding!