Why scatter plots show relationships in Matplotlib - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import the matplotlib library for plotting.

Matplotlib

import [1] as plt

Drag options to blanks, or click blank then click option'

Amatplotlib.pyplot

Bnumpy

Cpandas

Dseaborn

Attempts:

3 left

💡 Hint

Common Mistakes

Importing the wrong library like pandas or numpy for plotting.

Forgetting to import pyplot specifically.

We use matplotlib.pyplot as the standard library to create scatter plots in Python.

2fill in blank

medium

Complete the code to create a scatter plot with x and y data.

Matplotlib

plt.[1](x, y)

Drag options to blanks, or click blank then click option'

Ahist

Bline

Cbar

Dscatter

Attempts:

3 left

💡 Hint

Common Mistakes

Using plt.plot which draws lines, not scatter points.

Using bar or hist which are for different chart types.

The scatter function draws a scatter plot showing points for x and y values.

3fill in blank

hard

Fix the error in the code to show the plot correctly.

Matplotlib

plt.scatter(x, y)
plt.[1]()

Drag options to blanks, or click blank then click option'

Ashow

Bdraw

Cplot

Ddisplay

Attempts:

3 left

💡 Hint

Common Mistakes

Using plt.plot() or plt.draw() which do not display the plot window.

Forgetting to call any function to display the plot.

The plt.show() function displays the plot window so you can see the scatter plot.

4fill in blank

hard

Fill both blanks to create a scatter plot with labels for axes.

Matplotlib

plt.scatter(x, y)
plt.xlabel([1])
plt.[2]('Y Axis')
plt.show()

Drag options to blanks, or click blank then click option'

A'X Axis'

Bylabel

Ctitle

D'Scatter Plot'

Attempts:

3 left

💡 Hint

Common Mistakes

Using plt.title instead of plt.ylabel for y-axis label.

Not putting quotes around the axis label text.

Use plt.xlabel('X Axis') and plt.ylabel('Y Axis') to label the axes of the scatter plot.

5fill in blank

hard

Fill in the blanks to create a scatter plot with title and grid.

Matplotlib

plt.scatter(x, y)
plt.title([1])
plt.grid([2])
plt.show()

Drag options to blanks, or click blank then click option'

A'My Scatter Plot'

BTrue

CFalse

D'Scatter Data'

Attempts:

3 left

💡 Hint

Common Mistakes

Not using quotes for the title string.

Passing False to grid when you want to show grid lines.

Set the plot title with plt.title('My Scatter Plot') and enable grid lines with plt.grid(True).

Practice

1. What is the main reason we use scatter plots in data science?

easy

A. To sort data in ascending order

B. To see how two variables relate to each other

C. To calculate the average of a dataset

D. To create a list of unique values

Solution

1. Step 1: Understand the purpose of scatter plots

   Scatter plots show points representing two variables on a graph to visualize their relationship.

2. Step 2: Compare options with scatter plot use

   Calculating averages, sorting, or listing unique values are not visual tasks done by scatter plots.

3. Final Answer:

   To see how two variables relate to each other -> Option B

4. Quick Check:

   Scatter plots show relationships = C [OK]

Hint: Scatter plots show points for two variables to find relationships [OK]

Common Mistakes:

• Confusing scatter plots with bar charts
• Thinking scatter plots calculate statistics
• Believing scatter plots sort data

2. Which of the following is the correct way to create a scatter plot using matplotlib?

easy

A. plt.scatterplot(x, y)

B. plt.plot(x, y, 'scatter')

C. plt.bar(x, y)

D. plt.scatter(x, y)

Solution

1. Step 1: Recall matplotlib scatter plot syntax

   The correct function to create scatter plots in matplotlib is plt.scatter(x, y).

2. Step 2: Check other options for correctness

   plt.plot with 'scatter' is invalid, plt.bar creates bar charts, plt.scatterplot does not exist in matplotlib.

3. Final Answer:

   plt.scatter(x, y) -> Option D

4. Quick Check:

   Correct scatter plot function = D [OK]

Hint: Use plt.scatter(x, y) to plot scatter plots in matplotlib [OK]

Common Mistakes:

• Using plt.plot with wrong style
• Confusing bar charts with scatter plots
• Trying non-existent functions like plt.scatterplot

3. What will the following code show?

import matplotlib.pyplot as plt
x = [1, 2, 3, 4, 5]
y = [2, 4, 6, 8, 10]
plt.scatter(x, y)
plt.show()

medium

A. A scatter plot showing points forming a straight line going up

B. A scatter plot with points randomly scattered with no pattern

C. A bar chart with bars increasing in height

D. An error because plt.scatter needs labels

Solution

1. Step 1: Analyze the data points

   x and y values increase proportionally: y is 2 times x, so points lie on a straight line.

2. Step 2: Understand scatter plot output

   Scatter plot will show points aligned diagonally upwards, not random or bars, and no error occurs without labels.

3. Final Answer:

   A scatter plot showing points forming a straight line going up -> Option A

4. Quick Check:

   Proportional points form line = B [OK]

Hint: Check if y changes proportionally with x for line pattern [OK]

Common Mistakes:

• Thinking scatter plots create bar charts
• Expecting error without labels
• Assuming points are random without checking data

4. The code below is intended to plot a scatter plot but shows an error. What is the problem?

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

medium

A. plt.scatter cannot plot integers

B. plt.scatter requires labels before plotting

C. x and y lists have different lengths

D. plt.show() is missing

Solution

1. Step 1: Check the lengths of x and y

   x has 3 values, y has 2 values; scatter plot needs equal length lists for x and y.

2. Step 2: Verify other options

   Labels are optional, integers are valid, plt.show() is present, so these are not errors.

3. Final Answer:

   x and y lists have different lengths -> Option C

4. Quick Check:

   Equal length x and y needed = A [OK]

Hint: Ensure x and y lists have same length before plotting [OK]

Common Mistakes:

• Thinking labels are mandatory
• Believing plt.scatter can't plot integers
• Forgetting to check list lengths

5. You want to show a negative relationship between two variables using a scatter plot. Which data and code will best show this?

hard

A. x = [1, 2, 3, 4]; y = [10, 8, 6, 4]; plt.scatter(x, y)

B. x = [1, 2, 3, 4]; y = [2, 4, 6, 8]; plt.scatter(x, y)

C. x = [1, 2, 3, 4]; y = [4, 4, 4, 4]; plt.scatter(x, y)

D. x = [1, 2, 3, 4]; y = [1, 3, 2, 4]; plt.scatter(x, y)

Solution

1. Step 1: Identify negative relationship in data

   In x = [1, 2, 3, 4]; y = [10, 8, 6, 4]; plt.scatter(x, y), as x increases, y decreases, showing a negative relationship.

2. Step 2: Check other options for relationship type

   x = [1, 2, 3, 4]; y = [2, 4, 6, 8]; plt.scatter(x, y) shows positive relationship, C shows no change, D shows no clear pattern.

3. Final Answer:

   x = [1, 2, 3, 4]; y = [10, 8, 6, 4]; plt.scatter(x, y) -> Option A

4. Quick Check:

   y decreases as x increases = A [OK]

Hint: Negative relationship means y goes down as x goes up [OK]

Common Mistakes:

• Confusing positive and negative trends
• Choosing data with no clear pattern
• Ignoring constant y values