Dictionary creation in Python

Introduction

Dictionaries help you store pairs of related information, like names and phone numbers, so you can find things quickly.

When you want to link a word to its meaning, like a mini dictionary.

When you need to store settings with names and values, like volume or brightness.

When you want to count how many times each item appears in a list.

When you want to group data by a key, like students by their grade.

Syntax

Python

my_dict = {key1: value1, key2: value2, key3: value3}

Keys must be unique and usually are strings or numbers.

Values can be any type: numbers, strings, lists, or even other dictionaries.

Examples

This creates an empty dictionary with no items.

Python

empty_dict = {}

A dictionary with keys 'name', 'age', and 'city' storing related information.

Python

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

Keys are subjects and values are scores.

Python

scores = {"math": 90, "science": 85, "english": 88}

Sample Program

This program creates a dictionary to store a student's name, age, and courses. It then prints each piece of information.

Python

student = {
    "name": "John",
    "age": 20,
    "courses": ["Math", "History", "Science"]
}

print(f"Name: {student['name']}")
print(f"Age: {student['age']}")
print(f"Courses: {', '.join(student['courses'])}")

Important Notes

You can create dictionaries using the {} syntax or the dict() function.

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

Dictionaries do not keep order before Python 3.7, but from 3.7+ they remember the order items were added.

Summary

Dictionaries store data as key-value pairs for easy lookup.

Keys are unique and values can be any type.

Use curly braces {} to create dictionaries quickly.