Scatter plots in Data Analysis Python - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Scatter plot point count

What is the number of points plotted by this code?

Data Analysis Python

import matplotlib.pyplot as plt
import numpy as np
x = np.arange(10)
y = x**2
plt.scatter(x, y)
plt.show()
print(len(x))

A 0

B 9

C 11

D 10

💡 Hint

Count how many elements are in the x array.

The array x has 10 elements from 0 to 9, so 10 points are plotted.

❓ data_output

intermediate

Scatter plot color array length

What happens if the color array length does not match the number of points in this scatter plot?

Data Analysis Python

import matplotlib.pyplot as plt
import numpy as np
x = np.arange(5)
y = x * 2
colors = ['red', 'blue']
plt.scatter(x, y, c=colors)
plt.show()

A Ignores colors and plots default color

B Plots points with repeated colors

C Raises ValueError due to mismatch in colors length

D Plots only first two points with colors, others default

💡 Hint

Check if matplotlib requires color array length to match points.

Matplotlib requires the color array length to match the number of points. If not, it raises a ValueError.

❓ visualization

advanced

Scatter plot with size and color mapping

Which option produces a scatter plot where point size and color both vary with data?

Data Analysis Python

import matplotlib.pyplot as plt
import numpy as np
x = np.random.rand(50)
y = np.random.rand(50)
sizes = 100 * x
colors = y
plt.scatter(x, y, s=sizes, c=colors, cmap='viridis')
plt.colorbar()
plt.show()

A Points sized by x values and colored by y values with colorbar

B Points sized by x values but all colored blue without colorbar

C Points all same size and colored by x values without colorbar

D Points sized by y values and colored by x values with colorbar

💡 Hint

Check which variables control size and color in plt.scatter.

The code sets s=sizes where sizes = 100 * x, so size depends on x. Color c=colors is y, so color depends on y. Colorbar is shown.

🔧 Debug

advanced

Identify error in scatter plot code

What error does this code raise?

Data Analysis Python

import matplotlib.pyplot as plt
x = [1, 2, 3]
y = [4, 5]
plt.scatter(x, y)
plt.show()

A ValueError: x and y must be the same size

B TypeError: unsupported operand type(s)

C IndexError: list index out of range

D No error, plots successfully

💡 Hint

Check if x and y have the same length.

x has 3 elements, y has 2. Matplotlib requires equal length arrays for scatter plot, so it raises ValueError.

🚀 Application

expert

Interpreting scatter plot clustering

You have a scatter plot showing two clear clusters of points. What is the best data science interpretation?

A The scatter plot has an error and points are misplaced

B The data likely contains two distinct groups or categories

C The data is uniformly distributed with no pattern

D The data shows a linear relationship with no clusters

💡 Hint

Clusters in scatter plots usually indicate groups.

Clusters in scatter plots suggest the data points form distinct groups or categories.