Basic pie chart with plt.pie in Matplotlib - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this pie chart code?

Consider this Python code using matplotlib to create a pie chart. What will be the displayed percentages on the pie slices?

Matplotlib

import matplotlib.pyplot as plt
sizes = [10, 20, 30]
labels = ['A', 'B', 'C']
plt.pie(sizes, labels=labels, autopct='%1.1f%%')
plt.show()

A Slices labeled A: 16.7%, B: 33.3%, C: 50.0%

B Slices labeled A: 25%, B: 25%, C: 50%

C Slices labeled A: 10%, B: 20%, C: 30%

D Slices labeled A: 20%, B: 30%, C: 50%

💡 Hint

Percentages are calculated as each size divided by the total sum of sizes.

The total sum is 10 + 20 + 30 = 60. So, A is 10/60 = 16.7%, B is 20/60 = 33.3%, and C is 30/60 = 50%.

❓ data_output

intermediate

How many slices will the pie chart have?

Given this code snippet, how many slices will the pie chart display?

Matplotlib

import matplotlib.pyplot as plt
sizes = [5, 15, 25, 55]
plt.pie(sizes)
plt.show()

A 1 slice

B 5 slices

C 3 slices

D 4 slices

💡 Hint

Each number in sizes corresponds to one slice.

The list sizes has 4 numbers, so the pie chart will have 4 slices.

❓ visualization

advanced

Which option produces a pie chart with exploded slices?

Look at these four code snippets. Which one will create a pie chart where each slice is slightly separated (exploded) from the center?

A plt.pie([10, 20, 30], explode=[0, 0, 0])

B plt.pie([10, 20, 30], explode=[1, 0, 0])

C plt.pie([10, 20, 30], explode=[0.1, 0.1, 0.1])

D plt.pie([10, 20, 30], explode=[0.1, 0, 0.1])

💡 Hint

The explode parameter controls how far each slice is offset from the center.

Only option C explodes all slices equally by 0.1, separating each slice from the center.

🔧 Debug

advanced

What error does this pie chart code raise?

This code tries to create a pie chart but fails. What error will it raise?

Matplotlib

import matplotlib.pyplot as plt
sizes = [10, 20]
labels = ['A', 'B', 'C']
plt.pie(sizes, labels=labels)
plt.show()

A TypeError: unsupported operand type(s) for +: 'int' and 'str'

B ValueError: 'labels' must be the same length as 'sizes'

C IndexError: list index out of range

D No error, pie chart displays with missing label

💡 Hint

Labels list length must match sizes list length exactly.

The labels list has 3 items but sizes has 2, causing a ValueError about mismatched lengths.

🚀 Application

expert

Which option produces a pie chart with a shadow and start angle at 90 degrees?

You want a pie chart that has a shadow effect and starts drawing slices from the top (90 degrees). Which code snippet does this correctly?

A plt.pie([15, 25, 60], shadow=True, startangle=90)

B plt.pie([15, 25, 60], shadow=False, startangle=0)

C plt.pie([15, 25, 60], shadow=True, startangle=0)

D plt.pie([15, 25, 60], shadow=False, startangle=90)

💡 Hint

The shadow parameter adds a shadow, startangle rotates the start position in degrees.

Option A sets shadow=True for shadow and startangle=90 to start slices from the top.