Inverted axes in Matplotlib - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this inverted x-axis plot code?

Consider the following Python code using matplotlib. What will be the x-axis limits after running this code?

Matplotlib

import matplotlib.pyplot as plt
plt.plot([1, 2, 3, 4], [10, 20, 25, 30])
plt.gca().invert_xaxis()
limits = plt.gca().get_xlim()
print(limits)

A print outputs (4.0, 1.0)

B print outputs (1.0, 4.0)

C print outputs (10.0, 30.0)

D print outputs (30.0, 10.0)

💡 Hint

Remember that invert_xaxis() reverses the x-axis limits.

The invert_xaxis() method reverses the x-axis limits. Since the original x-axis limits are (1.0, 4.0), after inversion they become (4.0, 1.0).

❓ data_output

intermediate

What is the y-axis range after inversion?

Given this code snippet, what will be the y-axis limits printed?

Matplotlib

import matplotlib.pyplot as plt
plt.plot([0, 1, 2], [5, 10, 15])
plt.gca().invert_yaxis()
limits = plt.gca().get_ylim()
print(limits)

A print outputs (5.0, 15.0)

B print outputs (15.0, 5.0)

C print outputs (0.0, 2.0)

D print outputs (2.0, 0.0)

💡 Hint

invert_yaxis() reverses the y-axis limits.

The original y-axis limits are (5.0, 15.0). After invert_yaxis(), the limits become (15.0, 5.0).

❓ visualization

advanced

Which plot shows the x-axis inverted correctly?

You have four plots showing the same data but with different axis settings. Which plot correctly inverts the x-axis?

Matplotlib

import matplotlib.pyplot as plt
import numpy as np
x = np.arange(5)
y = x**2
fig, axs = plt.subplots(2, 2)

# Plot A
axs[0,0].plot(x, y)
axs[0,0].set_title('A')

# Plot B
axs[0,1].plot(x, y)
axs[0,1].invert_xaxis()
axs[0,1].set_title('B')

# Plot C
axs[1,0].plot(x, y)
axs[1,0].invert_yaxis()
axs[1,0].set_title('C')

# Plot D
axs[1,1].plot(x, y)
axs[1,1].invert_xaxis()
axs[1,1].invert_yaxis()
axs[1,1].set_title('D')

plt.tight_layout()
plt.show()

A Plot D

B Plot A

C Plot C

D Plot B

💡 Hint

invert_xaxis() flips the x-axis direction.

Only Plot B uses invert_xaxis() alone, which correctly inverts the x-axis. Plot D inverts both axes, Plot C inverts only y-axis, and Plot A has no inversion.

🧠 Conceptual

advanced

What happens if you invert both axes twice?

If you call invert_xaxis() and invert_yaxis() twice each on the same plot, what will be the final axis directions?

A Both axes will be inverted once, so both axes reversed

B Only x-axis will be inverted, y-axis normal

C Both axes will return to normal direction (not inverted)

D Only y-axis will be inverted, x-axis normal

💡 Hint

Inverting an axis twice cancels the inversion.

Calling invert_xaxis() or invert_yaxis() toggles the axis direction. Doing it twice returns the axis to its original direction.

🔧 Debug

expert

Why does this code not invert the x-axis as expected?

This code attempts to invert the x-axis but the plot shows normal x-axis direction. What is the reason?

Matplotlib

import matplotlib.pyplot as plt
plt.plot([1, 2, 3], [4, 5, 6])
plt.invert_xaxis()
plt.show()

A plt.invert_xaxis() is not a valid function; invert_xaxis() must be called on the Axes object

B The plot data is too small to show inversion

C invert_xaxis() only works after plt.show()

D The x-axis is inverted but the y-axis is overriding it

💡 Hint

Check where invert_xaxis() is called from.

invert_xaxis() is a method of the Axes object, not the pyplot module. Calling plt.invert_xaxis() causes an AttributeError and does not invert the axis.