Reading and writing CSV data in Python - Mini Project: Build & Apply

Reading and writing CSV data

📖 Scenario: You work in a small bookstore. You have a list of books with their titles and prices. You want to save this list to a CSV file and then read it back to check the data.

🎯 Goal: Learn how to write a list of dictionaries to a CSV file and then read the CSV file back into a list of dictionaries using Python.

📋 What You'll Learn

Create a list of dictionaries with book data

Set the CSV filename in a variable

Write the list of dictionaries to a CSV file

Read the CSV file back and print the data

💡 Why This Matters

🌍 Real World

CSV files are a common way to store and share tabular data like product lists, contacts, or sales records.

💼 Career

Knowing how to read and write CSV files is important for data processing, reporting, and automation tasks in many jobs.

1

Create the book data list

Create a list called books with these exact dictionaries: {'title': 'Python Basics', 'price': '29.99'}, {'title': 'Data Science', 'price': '39.99'}, and {'title': 'Web Development', 'price': '24.99'}.

Python

# Create the list of books with title and price
# Your code here

Need a hint?

Use square brackets [] to create a list and curly braces {} for dictionaries.

2

Set the CSV filename

Create a variable called filename and set it to the string 'books.csv'.

Python

books = [
    {'title': 'Python Basics', 'price': '29.99'},
    {'title': 'Data Science', 'price': '39.99'},
    {'title': 'Web Development', 'price': '24.99'}
]
# Set the CSV filename
# Your code here

Need a hint?

Use a simple string assignment like filename = 'books.csv'.

3

Write the books list to the CSV file

Import the csv module. Use open(filename, 'w', newline='') to open the file for writing. Create a csv.DictWriter with fieldnames ['title', 'price']. Write the header and then write all rows from books.

Python

books = [
    {'title': 'Python Basics', 'price': '29.99'},
    {'title': 'Data Science', 'price': '39.99'},
    {'title': 'Web Development', 'price': '24.99'}
]
filename = 'books.csv'

# Write the books list to the CSV file
# Your code here

Need a hint?

Remember to import csv and use DictWriter with the correct fieldnames.

4

Read the CSV file and print the data

Open the file filename for reading. Use csv.DictReader to read the rows. Convert the rows to a list called read_books. Print read_books.

Python

import csv

books = [
    {'title': 'Python Basics', 'price': '29.99'},
    {'title': 'Data Science', 'price': '39.99'},
    {'title': 'Web Development', 'price': '24.99'}
]
filename = 'books.csv'

with open(filename, 'w', newline='') as file:
    writer = csv.DictWriter(file, fieldnames=['title', 'price'])
    writer.writeheader()
    writer.writerows(books)

# Read the CSV file and print the data
# Your code here

Need a hint?

Use csv.DictReader and convert the reader to a list before printing.