Saturday, 31 January 2026

📊 Day 6: Percentage Stacked Bar Chart in Python

Samaksh Dubey January 31, 2026 Data Science No comments

🔹 What is a Percentage Stacked Bar Chart?

A Percentage Stacked Bar Chart displays data where each bar represents 100% of the total, and each segment shows the percentage contribution of a category to that total.
Instead of absolute values, it focuses on proportions.

🔹 When Should You Use It?

Use a percentage stacked bar chart when:

You want to compare relative contributions
Total values differ but composition matters
You want to visualize distribution changes over time
Absolute numbers are less important than percentage share

🔹 Example Scenario

Imagine you are analyzing Product A vs Product B sales over different years.
Even if total sales change each year, this chart helps you understand:

Which product dominates each year
How the market share shifts over time

🔹 Key Idea Behind It

👉 Every bar equals 100%
👉 Data is normalized into percentages
👉 Makes proportional comparison easier and clearer

🔹 Python Code (Percentage Stacked Bar Chart)


import matplotlib.pyplot as plt
import numpy as np 

years = ['2022', '2023', '2024']
product_a = np.array([50, 70, 40])
product_b = np.array([50, 30, 60]) 

total = product_a + product_b
a_percent = product_a / total * 100
b_percent = product_b / total * 100 

x = np.arange(len(years))

plt.bar(x, a_percent, label='Product A')
plt.bar(x, b_percent, bottom=a_percent, label='Product B') 
plt.xlabel('Year')
plt.ylabel('Percentage') 
plt.title('Percentage Stacked Bar Chart')
plt.xticks(x, years)
plt.legend()
plt.show()