Vertical bar chart with plt.bar in Matplotlib - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of a simple vertical bar chart code

What will be the height of the bars in the vertical bar chart produced by this code?

Matplotlib

import matplotlib.pyplot as plt

x = ['A', 'B', 'C']
y = [5, 3, 7]
plt.bar(x, y)
plt.show()

A [5, 7, 3]

B [3, 5, 7]

C [7, 5, 3]

D [5, 3, 7]

💡 Hint

Look at the y values passed to plt.bar as heights.

The heights of the bars correspond exactly to the y list values in order: 5, 3, then 7.

❓ data_output

intermediate

Number of bars in the chart

How many bars will be displayed by this code snippet?

Matplotlib

import matplotlib.pyplot as plt

labels = ['X', 'Y', 'Z', 'W']
values = [10, 20, 15, 5]
plt.bar(labels, values)
plt.show()

A 4

B 2

C 5

D 3

💡 Hint

Count the number of labels or values given.

There are 4 labels and 4 values, so 4 bars will be drawn.

❓ visualization

advanced

Identify the bar colors in the chart

Given this code, what color will the bars be?

Matplotlib

import matplotlib.pyplot as plt

categories = ['Cat1', 'Cat2']
heights = [8, 12]
plt.bar(categories, heights, color='green')
plt.show()

A Green

B Red

C Blue

D Yellow

💡 Hint

Check the color argument in plt.bar.

The color argument is set to 'green', so bars will be green.

🔧 Debug

advanced

Error type from mismatched data lengths

What error will this code raise when run?

Matplotlib

import matplotlib.pyplot as plt

labels = ['A', 'B', 'C']
values = [1, 2]
plt.bar(labels, values)
plt.show()

A TypeError: unsupported operand type(s)

B ValueError: x and height must be the same length

C IndexError: list index out of range

D No error, chart displays with missing bars

💡 Hint

Check if the number of labels matches the number of values.

Matplotlib requires the x and height lists to be the same length; otherwise, it raises a ValueError.

🚀 Application

expert

Calculate total bar height from grouped data

You have this data and code. What is the total height of all bars combined?

Matplotlib

import matplotlib.pyplot as plt

fruits = ['Apple', 'Banana', 'Cherry']
counts = [4, 7, 3]
plt.bar(fruits, counts)
plt.show()

A 10

B 7

C 14

D 4

💡 Hint

Add all the values in the counts list.

Sum of counts is 4 + 7 + 3 = 14, which is the total height of all bars combined.