Accessing values using keys in Python

Introduction

You use keys to find and get the exact value you want from a collection called a dictionary. It helps you quickly find information without searching everything.

When you have a list of items with names and you want to find the price of a specific item.

When you store user information like name and age, and want to get the age using the name.

When you keep settings in a program and want to check the value of a particular setting.

When you have a phone book stored as names and numbers and want to find a number by name.

Syntax

Python

value = dictionary[key]

The key must exist in the dictionary, or Python will give an error.

Keys are usually strings or numbers, and they are unique in the dictionary.

Examples

Get the price of 'apple' from the prices dictionary.

Python

prices = {'apple': 2, 'banana': 1}
print(prices['apple'])

Access the 'age' value from the person dictionary.

Python

person = {'name': 'Anna', 'age': 30}
age = person['age']
print(age)

Retrieve the brightness setting value.

Python

settings = {'volume': 10, 'brightness': 70}
print(settings['brightness'])

Sample Program

This program shows how to get and print values from a dictionary using keys.

Python

student = {'name': 'John', 'grade': 'A', 'age': 16}
print(f"Name: {student['name']}")
print(f"Grade: {student['grade']}")
print(f"Age: {student['age']}")

Important Notes

If you try to access a key that does not exist, Python will raise a KeyError.

You can use the get() method to avoid errors and provide a default value if the key is missing.

Keys must be immutable types like strings, numbers, or tuples.

Summary

Use keys to quickly find values in a dictionary.

Keys must exist or use get() to avoid errors.

Dictionaries store data in key-value pairs for easy access.