Figure-level methods vs axes-level in Matplotlib - Practice Questions

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of figure-level vs axes-level plot commands

What will be the output of the following code snippet using matplotlib?

import matplotlib.pyplot as plt

fig, ax = plt.subplots()
ax.plot([1, 2, 3], [4, 5, 6])
plt.title('My Title')
plt.show()

Note: plt.title() uses the pyplot interface acting on the current axes, ax.plot() is axes-level.

Matplotlib

import matplotlib.pyplot as plt

fig, ax = plt.subplots()
ax.plot([1, 2, 3], [4, 5, 6])
plt.title('My Title')
plt.show()

A The plot shows points connected by a line but no title is displayed.

B The plot shows points connected by a line with the title 'My Title' displayed above the plot.

C The plot is empty and the title 'My Title' is displayed above a blank figure.

D The code raises an error because plt.title() cannot be used with ax.plot().

💡 Hint

plt.title() sets the title for the current axes, and ax is the current axes after plt.subplots() and ax.plot().

The ax.plot() draws the line on the axes ax, which is the current axes after plt.subplots(). plt.title() sets the title on the current axes. Therefore, the plot shows the line with the title 'My Title'.

❓ Predict Output

intermediate

Correct way to set title on axes-level plot

Given the following code, which option shows the correct way to add a title to the axes-level plot?

import matplotlib.pyplot as plt

fig, ax = plt.subplots()
ax.plot([1, 2, 3], [4, 5, 6])
# Add title here
plt.show()

Matplotlib

import matplotlib.pyplot as plt

fig, ax = plt.subplots()
ax.plot([1, 2, 3], [4, 5, 6])
# Add title here
plt.show()

A ax.title('My Plot')

B fig.title('My Plot')

C plt.title('My Plot')

D ax.set_title('My Plot')

💡 Hint

Axes objects have a method to set the title directly.

The correct method to set the title on an axes object is ax.set_title(). Option D is invalid because ax.title() does not exist. Option D sets the title on the current axes but may not affect ax if multiple axes exist. Option D is invalid because fig.title() is not a valid method.

❓ data_output

advanced

Number of axes created by figure-level vs axes-level methods

Consider the following code:

import seaborn as sns
import matplotlib.pyplot as plt

iris = sns.load_dataset('iris')

sns.scatterplot(data=iris, x='sepal_length', y='sepal_width')
plt.show()

How many axes are created and displayed by this code?

Matplotlib

import seaborn as sns
import matplotlib.pyplot as plt

iris = sns.load_dataset('iris')

sns.scatterplot(data=iris, x='sepal_length', y='sepal_width')
plt.show()

A No axes are created; the plot is drawn directly on the figure.

B Multiple axes are created but only one is displayed.

C One axes is created and displayed with the scatter plot.

D Two axes are created and displayed side by side.

💡 Hint

Seaborn figure-level functions create a figure and one axes by default.

Seaborn's scatterplot is an axes-level function that creates one axes inside a figure. So, one axes is created and displayed.

🧠 Conceptual

advanced

Difference between figure-level and axes-level methods

Which statement best describes the difference between figure-level and axes-level methods in matplotlib and seaborn?

A Figure-level methods create and manage the entire figure including multiple axes, while axes-level methods operate on a single axes within a figure.

B Axes-level methods create the figure and figure-level methods create individual plots inside axes.

C Figure-level methods only work with 3D plots, axes-level methods only work with 2D plots.

D Axes-level methods are used only for styling, figure-level methods are used only for plotting data.

💡 Hint

Think about what each method controls: the whole figure or just one plot area.

Figure-level methods create and manage the entire figure, which can contain multiple axes (plots). Axes-level methods operate on a single axes object inside the figure, controlling one plot area.

🔧 Debug

expert

Why does the title not appear on the plot?

Examine the code below:

import matplotlib.pyplot as plt

fig, ax = plt.subplots()
ax.plot([1, 2, 3], [4, 5, 6])
fig.suptitle('Main Title')
ax.title('Sub Title')
plt.show()

Why does the plot show the main title but not the sub title?

Matplotlib

import matplotlib.pyplot as plt

fig, ax = plt.subplots()
ax.plot([1, 2, 3], [4, 5, 6])
fig.suptitle('Main Title')
ax.title('Sub Title')
plt.show()

A Because ax.title() is not a valid method; the correct method is ax.set_title().

B Because fig.suptitle() overrides any axes titles.

C Because the plot has no axes to set the title on.

D Because plt.show() must be called before setting titles.

💡 Hint

Check the method names for setting titles on axes.

The method ax.title() does not exist, so no sub title is set. The correct method to set a title on axes is ax.set_title(). The fig.suptitle() correctly sets the main title for the figure.