Combining Seaborn and Matplotlib - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of combined Seaborn and Matplotlib plot commands

What will be the color of the line plotted by Matplotlib after the Seaborn scatter plot?

Matplotlib

import matplotlib.pyplot as plt
import seaborn as sns

sns.set_style('darkgrid')
plt.scatter([1, 2, 3], [4, 5, 6], color='red')
plt.plot([1, 2, 3], [6, 5, 4])
plt.show()

A The line will be blue, the default Matplotlib color.

B The line will be red, matching the scatter points color.

C The line will be green, as Seaborn changes the default color cycle.

D The line will not appear because Seaborn disables Matplotlib plotting.

💡 Hint

Seaborn sets styles but does not change Matplotlib's default line color unless specified.

Seaborn's set_style changes the background grid style but does not affect the default line color of Matplotlib plots. The scatter points are red because explicitly set, but the line uses Matplotlib's default blue color.

❓ data_output

intermediate

Data output after combining Seaborn and Matplotlib plot commands

What is the number of lines plotted after running this code?

Matplotlib

import matplotlib.pyplot as plt
import seaborn as sns
import pandas as pd

df = pd.DataFrame({'x': [1, 2, 3], 'y': [3, 2, 1]})
sns.lineplot(data=df, x='x', y='y')
plt.plot([1, 2, 3], [1, 2, 3])
lines = plt.gca().get_lines()
print(len(lines))

A 3

B 1

C 2

D 0

💡 Hint

Count all lines added by both Seaborn and Matplotlib.

Seaborn's lineplot adds one line to the plot. The Matplotlib plot adds another line. So total lines are 2.

❓ visualization

advanced

Effect of Seaborn style on Matplotlib histogram

Which option best describes the visual style of the histogram after applying Seaborn's whitegrid style?

Matplotlib

import matplotlib.pyplot as plt
import seaborn as sns
import numpy as np

sns.set_style('whitegrid')
data = np.random.normal(size=100)
plt.hist(data, bins=10)
plt.show()

A Histogram bars are transparent with no background color.

B Histogram bars have grid lines behind them on a white background.

C Histogram bars have no grid lines and a black background.

D Histogram bars are plotted but the grid lines are removed.

💡 Hint

Recall what whitegrid style does in Seaborn.

The whitegrid style adds a white background with gray grid lines behind the plot elements, so the histogram bars appear with grid lines behind them on a white background.

🔧 Debug

advanced

Identify the error when combining Seaborn and Matplotlib

What error will this code raise?

Matplotlib

import matplotlib.pyplot as plt
import seaborn as sns

sns.set_style('dark')
plt.bar([1, 2, 3], [4, 5])
plt.show()

A ValueError: x and height must have the same length

B TypeError: set_style() got an unexpected keyword argument

C SyntaxError: invalid syntax in plt.bar call

D No error, the plot will display correctly

💡 Hint

Check the lengths of the x and height lists passed to plt.bar.

The plt.bar function requires the x and height lists to be the same length. Here, x has 3 elements but height has 2, causing a ValueError.

🚀 Application

expert

Combining Seaborn and Matplotlib for layered plots

You want to create a scatter plot with Seaborn and then add a horizontal line at y=0.5 using Matplotlib. Which code snippet correctly achieves this?

A

sns.scatterplot(x=[1,2,3], y=[0.4,0.6,0.8])
sns.axhline(y=0.5, color='red')
plt.show()

B

plt.scatter([1,2,3], [0.4,0.6,0.8])
sns.axhline(y=0.5, color='red')
plt.show()

C

plt.scatter([1,2,3], [0.4,0.6,0.8])
plt.axhline(y=0.5, color='red')
sns.show()

D

sns.scatterplot(x=[1,2,3], y=[0.4,0.6,0.8])
plt.axhline(y=0.5, color='red')
plt.show()

💡 Hint

Remember which library provides axhline and how to combine plots.

Seaborn does not have axhline. It is a Matplotlib function. So you create the scatter plot with Seaborn, then add the horizontal line with Matplotlib's plt.axhline, then show the plot.