Working with CSV files in Python - Mini Project: Build & Apply

Working with CSV files

📖 Scenario: You have a small store and keep track of your sales in a CSV file. You want to read this file, find sales above a certain amount, and show those sales.

🎯 Goal: Build a Python program that reads sales data from a CSV file, filters sales above a set amount, and prints those sales.

📋 What You'll Learn

Create a CSV file with sales data

Set a sales threshold value

Read the CSV file and filter sales above the threshold

Print the filtered sales

💡 Why This Matters

🌍 Real World

Many businesses store data in CSV files. Being able to read, filter, and process CSV data is useful for reports and analysis.

💼 Career

Data analysts, software developers, and anyone working with data often need to handle CSV files to extract useful information.

1

Create a CSV file with sales data

Create a CSV file named sales.csv with these exact contents including the header:
product,amount
Book,15
Pen,5
Notebook,20
Bag,50

Python

# Create the file sales.csv with the given content

Need a hint?

Use the csv module and csv.writer to write rows to the file.

2

Set a sales threshold value

Create a variable called threshold and set it to 10 to filter sales above this amount.

Python

import csv

with open('sales.csv', 'w', newline='') as file:
    writer = csv.writer(file)
    writer.writerow(['product', 'amount'])
    writer.writerow(['Book', '15'])
    writer.writerow(['Pen', '5'])
    writer.writerow(['Notebook', '20'])
    writer.writerow(['Bag', '50'])

# Create a variable called threshold and set it to 10
# Your code here

Need a hint?

Just create a variable named threshold and assign the number 10.

3

Read the CSV file and filter sales above the threshold

Read the sales.csv file using csv.DictReader. Create a list called filtered_sales that contains dictionaries for each sale where the amount is greater than threshold. Convert amount to an integer before comparing.

Python

import csv

with open('sales.csv', 'w', newline='') as file:
    writer = csv.writer(file)
    writer.writerow(['product', 'amount'])
    writer.writerow(['Book', '15'])
    writer.writerow(['Pen', '5'])
    writer.writerow(['Notebook', '20'])
    writer.writerow(['Bag', '50'])

threshold = 10

# Read sales.csv and create filtered_sales list with sales above threshold
# Your code here

Need a hint?

Use csv.DictReader to read rows as dictionaries. Check if int(row['amount']) is greater than threshold and add to filtered_sales.

4

Print the filtered sales

Use a for loop to print each dictionary in filtered_sales.

Python

import csv

with open('sales.csv', 'w', newline='') as file:
    writer = csv.writer(file)
    writer.writerow(['product', 'amount'])
    writer.writerow(['Book', '15'])
    writer.writerow(['Pen', '5'])
    writer.writerow(['Notebook', '20'])
    writer.writerow(['Bag', '50'])

threshold = 10

filtered_sales = []
with open('sales.csv', 'r', newline='') as file:
    reader = csv.DictReader(file)
    for row in reader:
        if int(row['amount']) > threshold:
            filtered_sales.append(row)

# Print each sale in filtered_sales
# Your code here

Need a hint?

Use a for loop to print each dictionary in filtered_sales.