Python Dictionaries: The Power of Key-Value Pairs

In real life, you often look things up using a label — like finding a contact in your phone using their name. In Python, a dictionary works the same way: it lets you store data as key-value pairs.

In this post, you’ll learn:

• What dictionaries are
• How to create and access dictionary data
• How to update, delete, and loop through them
• Real-life examples and tips

🧠 What Is a Dictionary?

A dictionary is a collection of key-value pairs. Each key is unique and maps to a value.

✅ Syntax:

my_dict = {
    "name": "Ada",
    "age": 25,
    "is_programmer": True
}

Here:

• "name", "age", and "is_programmer" are keys
• "Ada", 25, and True are values

🔍 Accessing Dictionary Values

Use the key name in square brackets or the .get() method:

print(my_dict["name"])         # Output: Ada
print(my_dict.get("age"))      # Output: 25

⚠️ Using .get() is safer — it returns None if the key doesn’t exist, instead of crashing.

✏️ Adding and Updating Values

my_dict["city"] = "Lagos"     # Add new key-value pair
my_dict["age"] = 26           # Update existing value

❌ Removing Items

my_dict.pop("is_programmer")  # Removes key "is_programmer"

Or remove the last item:

my_dict.popitem()

🔁 Looping Through a Dictionary

Loop through keys:

for key in my_dict:
    print(key)

Loop through keys and values:

for key, value in my_dict.items():
    print(f"{key}: {value}")

Output:

name: Ada
age: 26
city: Lagos

🔄 Useful Dictionary Methods

🧪 Real-Life Example

📚 Student Info

student = {
    "name": "Grace",
    "scores": [85, 92, 78],
    "is_enrolled": True
}

# Calculate average score
average = sum(student["scores"]) / len(student["scores"])
print(f"{student['name']}'s average score is {average}")

Output:

Grace's average score is 85.0

🧭 Summary

• Dictionaries store data as key-value pairs
• Keys must be unique
• You can add, update, delete, and loop through items easily

🚀 Try This

Create a dictionary for a book:

book = {
    "title": "The Python Journey",
    "author": "Jane Code",
    "pages": 250
}

Print:

• The title
• Add a “year”
• Update the page count
• Loop through and print everything