Box plot vs violin plot comparison in Matplotlib - Practice Questions

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of Box Plot Code

What will be the output of the following Python code that creates a box plot using matplotlib?

Matplotlib

import matplotlib.pyplot as plt
import numpy as np

data = np.random.normal(0, 1, 100)
plt.boxplot(data)
plt.savefig('boxplot.png')
plt.close()
print(type(data))

A SyntaxError

B <class 'list'>

C <class 'numpy.ndarray'>

D <class 'matplotlib.figure.Figure'>

💡 Hint

Check the type of the variable 'data' before plotting.

The variable 'data' is created using numpy's random.normal function, which returns a numpy ndarray. The print statement outputs its type.

❓ data_output

intermediate

Data Points in Violin Plot

Given the following code that creates a violin plot, how many data points are used to create the plot?

Matplotlib

import matplotlib.pyplot as plt
import numpy as np

data = np.concatenate([np.random.normal(0, 1, 50), np.random.normal(5, 1, 50)])
plt.violinplot(data)
plt.close()
print(len(data))

A 100

B 50

C 150

D 200

💡 Hint

Count the number of elements in each normal distribution and sum them.

The data is created by concatenating two arrays of 50 elements each, so total 100 points.

❓ visualization

advanced

Identify the Plot Type from Description

Which plot type shows the full distribution shape of the data along with median and quartiles?

A Box plot

B Violin plot

C Scatter plot

D Histogram

💡 Hint

One plot uses kernel density estimation to show distribution shape.

Violin plots show the full distribution shape using kernel density estimation, while box plots show summary statistics only.

🧠 Conceptual

advanced

Difference in Outlier Representation

Which statement correctly describes how outliers are represented in box plots and violin plots?

A Neither box plots nor violin plots show outliers explicitly.

B Violin plots show outliers as individual points; box plots do not explicitly mark outliers.

C Both box plots and violin plots show outliers as individual points.

D Box plots show outliers as individual points; violin plots do not explicitly mark outliers.

💡 Hint

Think about how each plot visualizes data extremes.

Box plots mark outliers as points beyond whiskers; violin plots show density but do not mark outliers explicitly.

🔧 Debug

expert

Error in Combined Box and Violin Plot Code

What error will this code produce when trying to plot both box and violin plots on the same axes?

Matplotlib

import matplotlib.pyplot as plt
import numpy as np

data = np.random.normal(size=100)
fig, ax = plt.subplots()
ax.boxplot(data)
ax.violinplot(data)
plt.show()

A No error; both plots display correctly.

B RuntimeWarning: Attempting to plot incompatible plot types

C ValueError: data must be 2D array for violinplot

D TypeError: violinplot() got an unexpected keyword argument

💡 Hint

Check if matplotlib supports plotting boxplot and violinplot on same axes.

Matplotlib allows plotting boxplot and violinplot on the same axes without error.