Rcparams for global defaults in Matplotlib - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this rcParams change?

Consider this code snippet that changes a global default in matplotlib using rcParams. What will be the color of the line in the plot?

Matplotlib

import matplotlib.pyplot as plt
plt.rcParams['lines.color'] = 'red'
plt.plot([1, 2, 3], [4, 5, 6])
line_color = plt.gca().lines[0].get_color()
print(line_color)

A 'black'

B 'blue'

C 'green'

D 'red'

💡 Hint

Changing plt.rcParams['lines.color'] sets the default line color globally.

The rcParams dictionary controls default styles in matplotlib. Setting lines.color to 'red' changes the default line color to red, so the plotted line will be red.

❓ data_output

intermediate

What is the default font size after this rcParams update?

After running the following code, what is the default font size used in matplotlib plots?

Matplotlib

import matplotlib.pyplot as plt
plt.rcParams['font.size'] = 14
font_size = plt.rcParams['font.size']
print(font_size)

A 14.0

B 12.0

C 10.0

D 16.0

💡 Hint

Look at the value assigned to plt.rcParams['font.size'].

Setting plt.rcParams['font.size'] to 14 changes the default font size for all text in matplotlib plots to 14 points.

🔧 Debug

advanced

Why does this rcParams setting not change the plot background color?

Look at this code snippet:

import matplotlib.pyplot as plt
plt.rcParams['axes.facecolor'] = 'yellow'
plt.plot([1, 2, 3], [4, 5, 6])
plt.show()

The plot background color does not change to yellow. Why?

A The plot uses a style that overrides rcParams, so the change is ignored.

B The key 'axes.facecolor' is misspelled and should be 'axes.face_color'.

C The background color changes only if set before importing matplotlib.

D The plot background color is controlled by 'figure.facecolor', not 'axes.facecolor'.

💡 Hint

Check if any style or context is overriding rcParams after setting it.

If a style or context is applied after setting rcParams, it can override those settings. The key 'axes.facecolor' is correct, and the background color can be changed at any time. The issue is that a style is overriding the rcParams change.

🧠 Conceptual

advanced

Which rcParams key controls the default grid line style?

In matplotlib, which rcParams key sets the default style of grid lines?

A 'grid.linewidth'

B 'grid.linestyle'

C 'grid.line_style'

D 'grid.style'

💡 Hint

Look for the key that controls line style specifically for grid lines.

The correct key is 'grid.linestyle'. It controls the pattern of grid lines, such as solid, dashed, or dotted. Other options are invalid keys or control different properties.

🚀 Application

expert

How to globally set all line widths to 3 and marker size to 10 using rcParams?

You want to set the default line width to 3 and the default marker size to 10 for all plots globally using rcParams. Which code snippet achieves this?

A

import matplotlib.pyplot as plt
plt.rcParams['line.width'] = 3
plt.rcParams['marker.size'] = 10

B

import matplotlib.pyplot as plt
plt.rcParams['lines.width'] = 3
plt.rcParams['markers.size'] = 10

C

import matplotlib.pyplot as plt
plt.rcParams['lines.linewidth'] = 3
plt.rcParams['lines.markersize'] = 10

D

import matplotlib.pyplot as plt
plt.rcParams['lines.linewidth'] = 10
plt.rcParams['lines.markersize'] = 3

💡 Hint

Check the exact keys for line width and marker size in rcParams.

The keys 'lines.linewidth' and 'lines.markersize' control the default line width and marker size respectively. The values must be set accordingly. Other keys are invalid or swapped values.