Donut chart variation in Matplotlib - Step-by-Step Execution

Concept Flow - Donut chart variation

Prepare data and labels

↓

Create pie chart with wedges

↓

Create donut hole with wedgeprops

↓

Display donut chart

↓

END

The flow shows preparing data, creating a pie chart, creating the donut hole with wedgeprops, then displaying the chart.

Execution Sample

Matplotlib

import matplotlib.pyplot as plt
sizes = [30, 20, 25, 25]
labels = ['A', 'B', 'C', 'D']
plt.pie(sizes, labels=labels, wedgeprops=dict(width=0.4))
plt.show()

This code creates a donut chart by setting wedge width less than 1 to create a hole in the pie.

Execution Table

Step	Action	Data/Parameter	Result/Output
1	Define sizes	[30, 20, 25, 25]	Data ready for chart
2	Define labels	['A', 'B', 'C', 'D']	Labels ready for chart
3	Call plt.pie	sizes and labels, wedge width=0.4	Pie chart wedges created with hole
4	Call plt.show	None	Donut chart displayed on screen
5	End	None	Execution stops after showing chart

💡 Chart displayed and program ends

Variable Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	Final
sizes	undefined	[30, 20, 25, 25]	[30, 20, 25, 25]	[30, 20, 25, 25]	[30, 20, 25, 25]
labels	undefined	undefined	['A', 'B', 'C', 'D']	['A', 'B', 'C', 'D']	['A', 'B', 'C', 'D']

Key Moments - 2 Insights

Why does setting wedgeprops width less than 1 create a donut shape?

Because wedgeprops width controls the thickness of pie slices. Setting it to 0.4 leaves a hole in the center, as shown in execution_table step 3.

What happens if we don't call plt.show()?

The chart will not display on screen. Execution_table step 4 shows plt.show triggers the display.

Visual Quiz - 3 Questions

Look at the execution_table, what is the value of 'sizes' after step 2?

A undefined

B ['A', 'B', 'C', 'D']

C [30, 20, 25, 25]

D [25, 25, 30, 20]

💡 Hint

Check variable_tracker row for 'sizes' after Step 2

At which step is the donut hole created in the chart?

A Step 3

B Step 4

C Step 1

D Step 2

💡 Hint

See execution_table step 3 where wedge width is set to 0.4

If wedgeprops width was set to 1, what would happen?

A Donut hole becomes bigger

B Chart becomes a full pie with no hole

C Chart will not display

D Labels disappear

💡 Hint

Recall wedge width controls slice thickness; 1 means full slices with no hole

Concept Snapshot

Donut chart variation in matplotlib:
- Use plt.pie() with wedgeprops={'width': value}
- width < 1 creates a hole (donut)
- Provide sizes and labels
- Call plt.show() to display
- Adjust width to control hole size

Full Transcript

This visual execution shows how to create a donut chart using matplotlib. First, we prepare the data sizes and labels. Then we call plt.pie with wedgeprops width set to 0.4 to create slices with a hole in the center. Finally, plt.show displays the donut chart. Variables sizes and labels remain unchanged after definition. The key step is setting wedgeprops width less than 1 to get the donut shape. Without plt.show, the chart won't appear. The quiz tests understanding of variable values and the effect of wedge width on the chart shape.

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)