Creating custom style sheets in Matplotlib - Practice Exercises

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of applying a custom style sheet

What will be the color of the line in the plot after applying the custom style sheet?

Matplotlib

import matplotlib.pyplot as plt
import matplotlib as mpl

custom_style = {
    'lines.linewidth': 3,
    'lines.color': 'red',
    'axes.titlesize': 'large'
}

mpl.rcParams.update(custom_style)
plt.plot([1, 2, 3], [1, 4, 9])
plt.title('Test Plot')
plt.show()

A The line will be thick and red in color.

B The line will be thin and blue in color.

C The line will be thick and blue in color.

D The line will be thin and red in color.

💡 Hint

Check the lines.linewidth and lines.color keys in the style dictionary.

The custom style sets lines.linewidth to 3, making the line thick, and lines.color to 'red', so the line color is red.

❓ data_output

intermediate

Number of style parameters applied

How many style parameters are applied when using the following custom style sheet?

Matplotlib

custom_style = {
    'lines.linewidth': 2,
    'axes.facecolor': 'lightgray',
    'grid.color': 'white',
    'grid.linestyle': '--'
}

import matplotlib.pyplot as plt
import matplotlib as mpl

mpl.rcParams.update(custom_style)
params = mpl.rcParams
count = sum(1 for key in custom_style if key in params)
print(count)

A 3

B 4

C 2

D 1

💡 Hint

Count how many keys in custom_style exist in mpl.rcParams.

All 4 keys in the custom style dictionary are valid matplotlib rcParams keys, so all 4 are applied.

🔧 Debug

advanced

Identify the error in custom style sheet usage

What error will occur when running this code?

Matplotlib

import matplotlib.pyplot as plt
import matplotlib as mpl

custom_style = {
    'lines.linewidth': 'thick',
    'axes.titlesize': 14
}

mpl.rcParams.update(custom_style)
plt.plot([1, 2, 3], [1, 4, 9])
plt.title('Test Plot')
plt.show()

A No error, plot shows with thick lines.

B KeyError because 'lines.linewidth' is not a valid rcParam.

C TypeError because 'lines.linewidth' expects a number, not a string.

D ValueError because 'axes.titlesize' must be a string, not an integer.

💡 Hint

Check the expected data type for lines.linewidth.

The lines.linewidth parameter expects a numeric value (float or int). Passing the string 'thick' causes a TypeError.

❓ visualization

advanced

Effect of custom style on grid appearance

Which option best describes the grid appearance after applying this custom style?

Matplotlib

import matplotlib.pyplot as plt
import matplotlib as mpl

custom_style = {
    'grid.color': 'green',
    'grid.linestyle': ':',
    'grid.linewidth': 2
}

mpl.rcParams.update(custom_style)
plt.plot([1, 2, 3], [1, 4, 9])
plt.grid(True)
plt.show()

A The grid lines are green, dotted, and thick.

B The grid lines are green, dashed, and thin.

C The grid lines are blue, dotted, and thick.

D The grid lines are blue, solid, and thin.

💡 Hint

Look at the grid.color, grid.linestyle, and grid.linewidth values.

The style sets grid color to green, linestyle to dotted (':'), and linewidth to 2 (thick).

🧠 Conceptual

expert

Understanding custom style sheet priority

Given the following code, what will be the color of the plot line?

Matplotlib

import matplotlib.pyplot as plt
import matplotlib as mpl

mpl.style.use('seaborn-darkgrid')
custom_style = {
    'lines.color': 'purple',
    'lines.linewidth': 1
}
mpl.rcParams.update(custom_style)
plt.plot([1, 2, 3], [1, 4, 9])
plt.show()

A The code will raise an error because multiple styles are used.

B The line color will be the seaborn default because it has higher priority.

C The line color will be blue because matplotlib defaults override styles.

D The line color will be purple because the custom style overrides the seaborn style.

💡 Hint

Consider the order of mpl.style.use() calls and which style is applied last.

Styles applied later override earlier ones. The custom style is applied after seaborn, so its settings take priority.