Axis scales (linear, log) in Matplotlib - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of linear vs log scale plot commands

What will be the y-axis limits after running this code snippet?

Matplotlib

import matplotlib.pyplot as plt
import numpy as np
x = np.linspace(1, 10, 10)
y = x ** 2
plt.plot(x, y)
plt.yscale('log')
plt.ylim(1, 100)
plt.show()
print(plt.gca().get_ylim())

A (1.0, 100.0)

B (0.0, 100.0)

C (1.0, 1000.0)

D (1.0, 10000.0)

💡 Hint

Remember that plt.ylim sets limits directly, even if scale is log.

The plt.ylim(1, 100) sets the y-axis limits explicitly. Even with log scale, the limits remain (1.0, 100.0).

❓ data_output

intermediate

Number of ticks on log scale axis

How many major ticks will appear on the y-axis after running this code?

Matplotlib

import matplotlib.pyplot as plt
import numpy as np
x = np.linspace(1, 100, 100)
y = x
plt.plot(x, y)
plt.yscale('log')
plt.show()
print(len(plt.gca().get_yticks()))

A 11

B 6

C 10

D 3

💡 Hint

Log scale major ticks usually appear at powers of 10.

The y-axis ranges from 1 to 100, so major ticks appear at 1, 10, 100, totaling 3 major ticks.

❓ visualization

advanced

Identify the plot with log scale on y-axis

Which plot shows a straight line when y = 10^x is plotted?

Matplotlib

import matplotlib.pyplot as plt
import numpy as np
x = np.linspace(0, 3, 100)
y = 10 ** x

plt.figure(figsize=(8, 4))
plt.subplot(1, 2, 1)
plt.plot(x, y)
plt.title('Plot 1')

plt.subplot(1, 2, 2)
plt.plot(x, y)
plt.yscale('log')
plt.title('Plot 2')
plt.show()

A Plot 2

B Both plots show straight lines

C Plot 1

D Neither plot shows a straight line

💡 Hint

Log scale turns exponential curves into straight lines.

Plot 2 uses a log scale on y-axis, so y=10^x appears as a straight line.

🧠 Conceptual

advanced

Effect of log scale on zero or negative values

What happens if you set y-axis to log scale but your data contains zero or negative values?

A Plot crashes with a SyntaxError

B Plot raises a ValueError or warning and skips those points

C Plot converts zero and negative values to positive automatically

D Plot shows zero and negative values normally on log scale

💡 Hint

Logarithm of zero or negative numbers is undefined.

Matplotlib raises a warning or error and ignores zero or negative values when using log scale.

🔧 Debug

expert

Why does this log scale plot show empty y-axis?

Given this code, why does the plot show no data on y-axis?

Matplotlib

import matplotlib.pyplot as plt
import numpy as np
x = np.linspace(0, 10, 100)
y = np.sin(x)
plt.plot(x, y)
plt.yscale('log')
plt.show()

A Because x values are zero, log scale fails on x-axis

B Because plt.plot does not support log scale

C Because y contains negative values, log scale cannot display them

D Because y values are too small to plot

💡 Hint

Check the range of y values and log scale requirements.

The sine function produces negative values, which cannot be shown on a log scale y-axis.