Grid lines configuration in Matplotlib - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Grid lines style and visibility

What is the output of this code snippet regarding grid lines on the plot?

Matplotlib

import matplotlib.pyplot as plt
plt.plot([1, 2, 3], [4, 5, 6])
plt.grid(True, linestyle='--', color='red')
plt.savefig('output.png')
plt.close()
print('Grid lines are visible with dashed red style')

A Grid lines are visible with dashed red style

B Grid lines are visible with solid blue style

C Code raises a TypeError

D No grid lines are visible

💡 Hint

Check the parameters passed to plt.grid() for style and color.

The plt.grid() function is called with True to enable grid lines, linestyle='--' for dashed lines, and color='red' for red color. So the output message matches the actual grid style.

❓ data_output

intermediate

Number of grid lines shown on a plot

Given this code, how many vertical grid lines will appear on the plot?

Matplotlib

import matplotlib.pyplot as plt
fig, ax = plt.subplots()
ax.plot([0, 1, 2, 3], [10, 20, 25, 30])
ax.set_xticks([0, 1, 2, 3])
ax.grid(True, axis='x')
plt.close()

A 4

B 3

C 0

D 1

💡 Hint

Count the number of x-ticks set and how grid lines correspond to ticks.

Grid lines appear at each x-tick. Since 4 x-ticks are set, 4 vertical grid lines will appear.

🔧 Debug

advanced

Identify the error in grid line configuration

What error does this code raise when run?

Matplotlib

import matplotlib.pyplot as plt
plt.plot([1, 2, 3], [4, 5, 6])
plt.grid(True, linestyle='dotted', color='green')
plt.show()

A AttributeError: 'NoneType' object has no attribute 'plot'

B TypeError: grid() got an unexpected keyword argument 'linestyle'

C ValueError: Invalid linestyle 'dotted'

D No error, grid lines show dotted green

💡 Hint

Check if 'dotted' is a valid linestyle in matplotlib.

No error is raised. Matplotlib recognizes 'dotted' as a valid linestyle (equivalent to ':'), so dotted green grid lines are displayed.

❓ visualization

advanced

Effect of grid line alpha transparency

Which option best describes the visual effect of setting grid line alpha to 0.1?

Matplotlib

import matplotlib.pyplot as plt
plt.plot([1, 2, 3], [3, 2, 1])
plt.grid(True, alpha=0.1)
plt.savefig('grid_alpha.png')
plt.close()

A Grid lines are invisible

B Grid lines appear very dark and bold

C Grid lines appear very faint and barely visible

D Grid lines are dashed

💡 Hint

Alpha controls transparency; lower alpha means more transparent.

Alpha value 0.1 means grid lines are mostly transparent, so they appear faint but visible.

🧠 Conceptual

expert

Understanding grid line layering in matplotlib

When multiple grid lines are drawn on a plot with overlapping styles, which matplotlib parameter controls whether grid lines appear above or below plot elements?

A alpha

B zorder

C linestyle

D color

💡 Hint

Think about which parameter controls drawing order in matplotlib.

The 'zorder' parameter controls the drawing order of plot elements, including grid lines, determining if they appear above or below other elements.