Box plot with plt.boxplot in Matplotlib - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What does this box plot code output?

Look at this code that creates a box plot. What will the plot show about the data?

Matplotlib

import matplotlib.pyplot as plt

data = [7, 8, 5, 6, 9, 10, 12, 15, 7, 8]
plt.boxplot(data)
plt.show()

A A box plot showing median around 9, with whiskers from 6 to 15

B A box plot showing median around 10, with whiskers from 7 to 15

C A box plot showing median around 8, with whiskers from 5 to 12

D A box plot showing median around 7.5, with whiskers from 5 to 15

💡 Hint

Remember the median is the middle value when data is sorted.

The median of the data is 8. The whiskers extend to the minimum and maximum values within 1.5 times the interquartile range, which are 5 and 12 here.

❓ data_output

intermediate

How many outliers are shown by this box plot?

This code creates a box plot. How many points will be shown as outliers?

Matplotlib

import matplotlib.pyplot as plt

data = [10, 12, 14, 15, 16, 18, 20, 100, 105]
plt.boxplot(data)
plt.show()

A 2

B 0

C 1

D 3

💡 Hint

Outliers are points outside 1.5 times the interquartile range from the quartiles.

The values 100 and 105 are far from the rest and will be marked as outliers, so 2 points.

❓ visualization

advanced

Which option produces a box plot with horizontal orientation?

You want to create a horizontal box plot using plt.boxplot. Which code does this correctly?

A plt.boxplot(data, vert=False)

B plt.boxplot(data, orientation='horizontal')

C plt.boxplot(data, vert=True)

D plt.boxplot(data, horizontal=True)

💡 Hint

Check the vert parameter in plt.boxplot.

The correct parameter to set horizontal orientation is vert=False. orientation='horizontal' is not a valid parameter.

🧠 Conceptual

advanced

What does the box in a box plot represent?

In a box plot created by plt.boxplot, what does the box itself show?

A The range between minimum and maximum values

B The median and outliers

C The mean and standard deviation

D The interquartile range (from Q1 to Q3)

💡 Hint

Think about the middle 50% of the data.

The box shows the interquartile range, which is the range between the first quartile (Q1) and third quartile (Q3).

🔧 Debug

expert

Why does this box plot code raise an error?

This code tries to create a box plot but raises an error. What is the cause?

Matplotlib

import matplotlib.pyplot as plt

data = [1, 2, 3, 4, 5]
plt.boxplot(data, orientation='sideways')
plt.show()

A plt.boxplot does not accept keyword arguments

B orientation='sideways' is not a valid parameter value

C plt.boxplot requires data to be a pandas DataFrame

D data must be a numpy array, not a list

💡 Hint

Check the parameters accepted by plt.boxplot.

plt.boxplot does not accept an 'orientation' parameter (use 'vert' instead). Passing 'orientation' causes an error.