Chunked reading for large files in Pandas - Mini Project: Build & Apply

Chunked reading for large files

📖 Scenario: Imagine you have a very large sales data file that is too big to load into memory all at once. You want to read it in smaller parts, called chunks, to analyze the total sales amount.

🎯 Goal: Build a program that reads a large CSV file in chunks using pandas, sums the sales amounts from each chunk, and then shows the total sales.

📋 What You'll Learn

Use pandas to read CSV files in chunks

Create a variable to hold the running total of sales

Loop over each chunk and add the sales amounts

Print the final total sales amount

💡 Why This Matters

🌍 Real World

Large datasets often cannot fit into memory all at once. Reading data in chunks helps analyze big files efficiently.

💼 Career

Data scientists and analysts use chunked reading to handle big data files without crashing their computers.

1

Create a pandas chunk reader

Import pandas as pd and create a variable called chunk_reader that reads the CSV file named 'large_sales.csv' in chunks of size 1000 using pd.read_csv with the chunksize parameter.

Pandas

# Import pandas and create chunk_reader to read 'large_sales.csv' in chunks of 1000 rows
# Your code here

Need a hint?

Use pd.read_csv with chunksize=1000 to read the file in parts.

2

Create a total sales variable

Create a variable called total_sales and set it to 0. This will hold the sum of sales amounts as you read each chunk.

Pandas

import pandas as pd
chunk_reader = pd.read_csv('large_sales.csv', chunksize=1000)
# Create total_sales variable and set it to 0
# Your code here

Need a hint?

Just create a variable total_sales and assign it 0.

3

Sum sales amounts from each chunk

Use a for loop with the variable chunk to iterate over chunk_reader. Inside the loop, add the sum of the 'sales_amount' column from chunk to total_sales.

Pandas

import pandas as pd
chunk_reader = pd.read_csv('large_sales.csv', chunksize=1000)
total_sales = 0
# Loop over chunk_reader and add sum of 'sales_amount' from each chunk to total_sales
# Your code here

Need a hint?

Use for chunk in chunk_reader: and inside add chunk['sales_amount'].sum() to total_sales.

4

Print the total sales amount

Write a print statement to display the text 'Total sales amount:' followed by the value of total_sales.

Pandas

import pandas as pd
chunk_reader = pd.read_csv('large_sales.csv', chunksize=1000)
total_sales = 0
for chunk in chunk_reader:
    total_sales += chunk['sales_amount'].sum()
# Print the total sales amount
# Your code here

Need a hint?

Use print('Total sales amount:', total_sales) to show the result.