Small multiples (facet grid) in Matplotlib - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of a simple facet grid plot

What will be the shape of the figure created by this code using matplotlib's subplots for small multiples?

Matplotlib

import matplotlib.pyplot as plt
import numpy as np

x = np.linspace(0, 10, 100)
fig, axs = plt.subplots(2, 3)
for i, ax in enumerate(axs.flatten()):
    ax.plot(x, np.sin(x + i))
plt.close(fig)
print(fig.get_size_inches())

A [12.0 8.0]

B [18.0 12.0]

C [6.0 4.0]

D [8.0 6.0]

💡 Hint

The default figsize for plt.subplots is (6, 4) inches.

By default, plt.subplots creates a figure of size 6 inches wide and 4 inches tall unless specified otherwise.

❓ data_output

intermediate

Number of subplots created

How many subplots will be created by this code snippet?

Matplotlib

import matplotlib.pyplot as plt
fig, axs = plt.subplots(3, 4)
print(len(axs.flatten()))

A 7

B 12

C 3

D 4

💡 Hint

Count rows times columns.

3 rows times 4 columns equals 12 subplots.

❓ visualization

advanced

Identify the correct facet grid layout

Which option shows the correct arrangement of subplots for this code?

Matplotlib

import matplotlib.pyplot as plt
import numpy as np
x = np.linspace(0, 2 * np.pi, 100)
fig, axs = plt.subplots(2, 2)
for i, ax in enumerate(axs.flatten()):
    ax.plot(x, np.sin(x + i))
plt.close(fig)
# The question is about the layout of subplots in a 2x2 grid.

A Four plots arranged in 2 rows and 2 columns

B Four plots arranged in 1 row and 4 columns

C Two plots arranged in 2 rows and 1 column

D Three plots arranged in 3 rows and 1 column

💡 Hint

Check the arguments of plt.subplots(2, 2).

plt.subplots(2, 2) creates a grid with 2 rows and 2 columns, so 4 plots arranged accordingly.

🔧 Debug

advanced

Error in facet grid subplot indexing

What error will this code raise?

Matplotlib

import matplotlib.pyplot as plt
fig, axs = plt.subplots(2, 2)
axs[2].plot([1, 2, 3], [4, 5, 6])

A IndexError: index 2 is out of bounds for axis 0 with size 2

B AttributeError: 'AxesSubplot' object has no attribute 'plot'

C TypeError: 'AxesSubplot' object is not subscriptable

D No error, plot will be created

💡 Hint

axs is a 2D array of shape (2, 2).

axs is a 2x2 array, so axs[2] is out of bounds. Indexing must be two-dimensional or flattened first.

🚀 Application

expert

Creating a facet grid with shared axes

Which code snippet correctly creates a 3x2 facet grid with shared x and y axes using matplotlib?

A fig, axs = plt.subplots(3, 2, sharex=False, sharey=True)

B fig, axs = plt.subplots(3, 2, sharex=True, sharey=False)

C fig, axs = plt.subplots(2, 3, sharex=True, sharey=True)

D fig, axs = plt.subplots(3, 2, sharex=True, sharey=True)

💡 Hint

Check the order of rows and columns and the sharex/sharey parameters.

plt.subplots(3, 2, sharex=True, sharey=True) creates 3 rows and 2 columns with shared axes.