Donut chart variation in Matplotlib - Mini Project: Build & Apply

Donut Chart Variation

📖 Scenario: You work at a bakery that sells different types of donuts. You want to show which donut flavors are most popular using a donut chart. This chart will help your team understand customer preferences visually.

🎯 Goal: Create a donut chart using matplotlib to display the sales distribution of donut flavors. You will start by setting up the sales data, then configure the chart style, create the donut chart, and finally display it.

📋 What You'll Learn

Use a dictionary called donut_sales with exact keys and values for donut flavors and their sales.

Create a variable called colors to hold a list of colors for the chart slices.

Use matplotlib.pyplot.pie to create a pie chart with a hole in the center to make it a donut chart.

Display the donut chart with labels and a legend.

💡 Why This Matters

🌍 Real World

Donut charts are useful to show parts of a whole in sales, survey results, or any category distribution in a visually appealing way.

💼 Career

Data analysts and scientists often use donut charts to communicate insights clearly to non-technical stakeholders.

1

Set up donut sales data

Create a dictionary called donut_sales with these exact entries: 'Glazed': 40, 'Chocolate': 35, 'Strawberry': 25.

Matplotlib

# Create the donut_sales dictionary with exact entries
# Your code here

Hint

Use curly braces {} to create the dictionary with keys as donut flavors and values as sales numbers.

2

Configure colors for the donut chart

Create a list called colors with these exact color strings: '#ff9999', '#66b3ff', '#99ff99'.

Matplotlib

donut_sales = {'Glazed': 40, 'Chocolate': 35, 'Strawberry': 25}
# Create the colors list with exact color codes
# Your code here

Hint

Colors are strings inside a list. Use square brackets [] and separate colors with commas.

3

Create the donut chart

Import matplotlib.pyplot as plt. Use plt.pie with donut_sales.values() for sizes, labels=donut_sales.keys(), colors=colors, and wedgeprops={{'width': 0.4}} to create a donut chart.

Matplotlib

donut_sales = {'Glazed': 40, 'Chocolate': 35, 'Strawberry': 25}
colors = ['#ff9999', '#66b3ff', '#99ff99']
# Import matplotlib.pyplot as plt
# Create a donut chart using plt.pie with wedgeprops to make a hole
# Your code here

Hint

Use import matplotlib.pyplot as plt at the top. The wedgeprops with {'width': 0.4} creates the donut hole.

4

Display the donut chart

Add plt.title("Donut Sales Distribution") to set the chart title. Then call plt.show() to display the chart.

Matplotlib

import matplotlib.pyplot as plt

donut_sales = {'Glazed': 40, 'Chocolate': 35, 'Strawberry': 25}
colors = ['#ff9999', '#66b3ff', '#99ff99']

plt.pie(donut_sales.values(), labels=donut_sales.keys(), colors=colors, wedgeprops={'width': 0.4})
# Add a title and show the plot
# Your code here

Hint

Use plt.title() to add a title. plt.show() displays the chart window.

Practice

1.

What is the main difference between a donut chart and a pie chart in matplotlib?

easy

A. A donut chart has a hole in the center, a pie chart does not.

B. A donut chart uses bars, a pie chart uses slices.

C. A donut chart shows data over time, a pie chart shows categories.

D. A donut chart is 3D, a pie chart is 2D.

Solution

1. Step 1: Understand pie chart basics

   A pie chart divides a circle into slices representing parts of a whole.

2. Step 2: Identify donut chart feature

   A donut chart is a pie chart with a hole in the center, making it look like a donut.

3. Final Answer:

   A donut chart has a hole in the center, a pie chart does not. -> Option A

4. Quick Check:

   Donut chart = pie chart + hole [OK]

Hint: Donut chart = pie chart with center hole [OK]

Common Mistakes:

• Thinking donut charts use bars
• Confusing donut charts with 3D charts
• Believing donut charts show time series

2.

Which matplotlib code snippet correctly creates a donut chart with a hole size controlled by wedgeprops?

import matplotlib.pyplot as plt
sizes = [30, 40, 30]
plt.pie(sizes, wedgeprops=???)
plt.show()

easy

A. wedgeprops={'height': 0.5}

B. wedgeprops={'radius': 0.5}

C. wedgeprops={'width': 0.5}

D. wedgeprops={'size': 0.5}

Solution

1. Step 1: Recall donut hole control

   The hole size in a donut chart is set by the 'width' key inside wedgeprops.

2. Step 2: Match correct syntax

   Using wedgeprops={'width': 0.5} creates a hole half the radius size.

3. Final Answer:

   wedgeprops={'width': 0.5} -> Option C

4. Quick Check:

   wedgeprops width controls hole size [OK]

Hint: Use wedgeprops={'width': value} for donut hole [OK]

Common Mistakes:

• Using 'radius' instead of 'width'
• Using 'height' or 'size' keys incorrectly
• Omitting wedgeprops entirely

3.

What will be the visual output of this code?

import matplotlib.pyplot as plt
sizes = [10, 20, 30]
plt.pie(sizes, wedgeprops={'width': 0.3})
plt.show()

medium

A. A donut chart with a thin ring shape

B. A pie chart with no hole in the center

C. A donut chart with a very large hole

D. A bar chart instead of a pie chart

Solution

1. Step 1: Analyze wedgeprops width value

   The width is set to 0.3, meaning the donut hole is 70% of the radius.

2. Step 2: Visualize the chart shape

   This creates a donut chart with a thin ring shape because the hole is large but not full radius.

3. Final Answer:

   A donut chart with a thin ring shape -> Option A

4. Quick Check:

   width=0.3 means thin donut ring [OK]

Hint: Smaller width = thinner donut ring [OK]

Common Mistakes:

• Thinking width=0.3 means no hole
• Confusing hole size with radius
• Expecting a bar chart output

4.

Identify the error in this donut chart code and select the fix:

import matplotlib.pyplot as plt
sizes = [25, 35, 40]
plt.pie(sizes, wedgeprops={'width': '0.5'})
plt.show()

medium

A. Add labels parameter

B. Remove wedgeprops entirely

C. Change 'width' to 'radius'

D. Change '0.5' to 0.5 (string to float)

Solution

1. Step 1: Check wedgeprops value type

   The width value is given as a string '0.5', but it must be a number (float).

2. Step 2: Correct the data type

   Changing '0.5' to 0.5 fixes the type error and creates the donut hole properly.

3. Final Answer:

   Change '0.5' to 0.5 (string to float) -> Option D

4. Quick Check:

   width must be float, not string [OK]

Hint: Use numbers, not strings, for wedgeprops values [OK]

Common Mistakes:

• Using string instead of float for width
• Changing width key incorrectly
• Ignoring type errors

5.

You want to create a donut chart showing sales distribution with a hole size that leaves 40% thickness for the slices. Which wedgeprops value should you use?

hard

A. wedgeprops={'width': 0.4}

B. wedgeprops={'width': 0.6}

C. wedgeprops={'width': 0.2}

D. wedgeprops={'width': 1.0}

Solution

1. Step 1: Understand width meaning

   The 'width' value is the thickness of the slices as a fraction of the radius.

2. Step 2: Calculate width for 40% thickness

   For 40% thickness for the slices, set width=0.6 (leaving a hole size of 40%).

3. Final Answer:

   wedgeprops={'width': 0.6} -> Option B

4. Quick Check:

   width=0.6 gives 40% slice thickness [OK]

Hint: Width = slice thickness fraction (1 - hole size) [OK]

Common Mistakes:

• Confusing width with hole size
• Using width less than hole thickness
• Setting width to 1 (no hole)