Matplotlib for data visualization in Raspberry Pi - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this Matplotlib code?

Consider the following Python code using Matplotlib. What will be the color of the plotted line?

Raspberry Pi

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

A A green dashed line

B A blue solid line

C A red dotted line

D A black dash-dot line

💡 Hint

Look at the format string 'g--' used in the plot function.

The format string 'g--' means green color ('g') and dashed line style ('--').

❓ data_output

intermediate

How many bars will be displayed in this bar chart?

Given this code snippet, how many bars will appear in the bar chart?

Raspberry Pi

import matplotlib.pyplot as plt
categories = ['A', 'B', 'C', 'D']
values = [5, 7, 3, 8]
plt.bar(categories, values)
plt.show()

A 3 bars

B 4 bars

C 5 bars

D 1 bar

💡 Hint

Count the number of categories provided.

There are 4 categories: 'A', 'B', 'C', and 'D', so 4 bars will be shown.

❓ visualization

advanced

Which option produces a scatter plot with red circles?

Which code snippet will produce a scatter plot with red circle markers?

A

plt.scatter([1,2,3], [4,5,6], color='blue', marker='x')
plt.show()

B

plt.scatter([1,2,3], [4,5,6], c='red', marker='x')
plt.show()

C

plt.scatter([1,2,3], [4,5,6], c='red', marker='o')
plt.show()

D

plt.scatter([1,2,3], [4,5,6], c='green', marker='s')
plt.show()

💡 Hint

Check the color and marker shape parameters.

Option C uses 'c' for color set to 'red' and marker 'o' for circles.

🔧 Debug

advanced

What error does this Matplotlib code raise?

What error will this code produce when run?

Raspberry Pi

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

A No error, plot displays correctly

B TypeError: unsupported operand type(s)

C SyntaxError: invalid syntax

D ValueError: x and y must have same first dimension

💡 Hint

Check the lengths of x and y lists.

The x list has 3 elements but y has 2, so Matplotlib raises a ValueError.

🚀 Application

expert

Which option produces a line plot with a legend and grid?

Which code snippet correctly creates a line plot with a legend labeled 'Data' and a grid shown?

A

plt.plot([1,2,3], [4,5,6], label='Data')
plt.legend()
plt.grid(True)
plt.show()

B

plt.plot([1,2,3], [4,5,6])
plt.legend('Data')
plt.grid(True)
plt.show()

C

plt.plot([1,2,3], [4,5,6], label='Data')
plt.grid()
plt.show()

D

plt.plot([1,2,3], [4,5,6], label='Data')
plt.legend()
plt.grid(False)
plt.show()

💡 Hint

Look for correct usage of legend and grid functions.

Option A correctly sets the label, calls plt.legend() without arguments, and enables grid with plt.grid(True).