Basic scatter plot with plt.scatter in Matplotlib - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

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

Matplotlib

import matplotlib.pyplot as plt
x = [1, 2, 3, 4, 5]
y = [5, 7, 4, 6, 8]
plt.[1](x, y)
plt.show()

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

Ascatter

Bhist

Cbar

Dplot

Attempts:

3 left

💡 Hint

Common Mistakes

Using plt.plot instead of plt.scatter will create a line plot, not a scatter plot.

Using plt.bar or plt.hist will create bar or histogram plots, which are different.

The plt.scatter function creates a scatter plot using the x and y data points.

2fill in blank

medium

Complete the code to add a title to the scatter plot.

Matplotlib

import matplotlib.pyplot as plt
x = [1, 2, 3]
y = [4, 5, 6]
plt.scatter(x, y)
plt.[1]('My Scatter Plot')
plt.show()

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

Axlabel

Bylabel

Ctitle

Dlegend

Attempts:

3 left

💡 Hint

Common Mistakes

Using plt.xlabel or plt.ylabel adds axis labels, not the plot title.

Using plt.legend adds a legend, not a title.

The plt.title function adds a title to the plot.

3fill in blank

hard

Fix the error in the code to correctly plot a scatter plot with red color.

Matplotlib

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

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

Ar

B'red'

Cred

D'r'

Attempts:

3 left

💡 Hint

Common Mistakes

Passing color without quotes causes a NameError.

Using just r without quotes is invalid for color.

The color value must be a string, so it needs quotes like 'red'.

4fill in blank

hard

Fill both blanks to create a scatter plot with blue points and label the x-axis as 'Age'.

Matplotlib

import matplotlib.pyplot as plt
x = [20, 25, 30]
y = [5, 7, 9]
plt.scatter(x, y, color=[1])
plt.[2]('Age')
plt.show()

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

A'blue'

B'Age'

Cxlabel

Dylabel

Attempts:

3 left

💡 Hint

Common Mistakes

Using ylabel instead of xlabel for the x-axis label.

Not putting the color name in quotes.

Use color='blue' to set point color and plt.xlabel('Age') to label the x-axis.

5fill in blank

hard

Fill all three blanks to create a scatter plot with green points, label the y-axis as 'Height', and add a plot title 'Height vs Age'.

Matplotlib

import matplotlib.pyplot as plt
x = [18, 22, 26]
y = [160, 170, 180]
plt.scatter(x, y, color=[1])
plt.[2]('Height')
plt.[3]('Height vs Age')
plt.show()

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

A'green'

Bylabel

Ctitle

Dxlabel

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up xlabel and ylabel.

Forgetting quotes around color name.

Using plt.xlabel instead of plt.title for the plot title.

Use color='green' for points, plt.ylabel('Height') for y-axis label, and plt.title('Height vs Age') for the plot title.

Practice

1. What does the plt.scatter(x, y) function do in matplotlib?

easy

A. It creates a line plot connecting x and y points.

B. It creates a scatter plot showing points for x and y data.

C. It creates a bar chart for x and y values.

D. It creates a histogram of x values only.

Solution

1. Step 1: Understand the purpose of plt.scatter

   The function plt.scatter is designed to plot individual points based on two lists or arrays, x and y, showing their relationship.

2. Step 2: Compare with other plot types

   Unlike line plots or bar charts, scatter plots show points without connecting lines or bars.

3. Final Answer:

   It creates a scatter plot showing points for x and y data. -> Option B

4. Quick Check:

   Scatter plot = points for x and y [OK]

Hint: Scatter plots show points, not lines or bars [OK]

Common Mistakes:

• Confusing scatter plot with line plot
• Thinking it creates bars or histograms
• Assuming it only plots x values

2. Which of the following is the correct syntax to create a scatter plot with x and y lists (x horizontal, y vertical) using matplotlib?

easy

A. plt.scatter(x, y)

B. plt.scatter(y, x)

C. plt.plot.scatter(x, y)

D. scatter.plot(x, y)

Solution

1. Step 1: Recall the correct function call

   The correct function to create a scatter plot in matplotlib is plt.scatter(x, y), where x and y are data lists.

2. Step 2: Identify incorrect syntax

   Options with reversed arguments or wrong method chaining like plt.plot.scatter or scatter.plot are invalid.

3. Final Answer:

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

4. Quick Check:

   Correct syntax = plt.scatter(x, y) [OK]

Hint: Use plt.scatter(x, y) exactly for scatter plots [OK]

Common Mistakes:

• Swapping x and y arguments
• Using plt.plot.scatter instead of plt.scatter
• Calling scatter on wrong object

3. What will be the output of this code?

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

medium

A. An error because plt.show() is missing.

B. A line plot connecting points (1,4), (2,5), and (3,6).

C. A scatter plot with points at (1,4), (2,5), and (3,6).

D. A bar chart with bars at x positions 1, 2, 3.

Solution

1. Step 1: Understand plt.scatter with given data

   The code plots points at coordinates from lists x and y: (1,4), (2,5), and (3,6).

2. Step 2: Confirm plt.show() displays the plot

   The plt.show() command displays the scatter plot window with these points.

3. Final Answer:

   A scatter plot with points at (1,4), (2,5), and (3,6). -> Option C

4. Quick Check:

   Scatter plot points = (1,4), (2,5), (3,6) [OK]

Hint: Scatter plots show points at (x[i], y[i]) pairs [OK]

Common Mistakes:

• Thinking plt.scatter creates line plots
• Assuming plt.show() is optional and causes error
• Confusing scatter with bar chart

4. Identify the error in this code snippet:

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

medium

A. plt.scatter requires numpy arrays, not lists.

B. The code is correct and runs without error.

C. plt.show() is missing to display the plot.

D. x and y lists have different lengths causing an error.

Solution

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

   The x list has 3 elements, but y has only 2 elements. This mismatch causes plt.scatter to raise a ValueError.

2. Step 2: Understand plt.scatter input requirements

   Both x and y must have the same number of points to plot pairs correctly.

3. Final Answer:

   x and y lists have different lengths causing an error. -> Option D

4. Quick Check:

   Equal length x and y needed [OK]

Hint: x and y must be same length for scatter plot [OK]

Common Mistakes:

• Ignoring length mismatch of x and y
• Thinking plt.scatter needs numpy arrays only
• Assuming plt.show() missing causes error

5. You want to plot points with x = [1, 2, 3, 4] and y = [10, 20, 30, 40], but color points red if y > 25 and blue otherwise. Which code correctly does this?

hard

A. colors = ['red' if val > 25 else 'blue' for val in y]
plt.scatter(x, y, c=colors)
plt.show()

B. plt.scatter(x, y, color=['red' if y > 25 else 'blue'])
plt.show()

C. plt.scatter(x, y, c='red' if y > 25 else 'blue')
plt.show()

D. colors = ['red' if x > 25 else 'blue' for x in x]
plt.scatter(x, y, c=colors)
plt.show()

Solution

1. Step 1: Create color list based on y values

   We use a list comprehension to assign 'red' if y value is greater than 25, else 'blue'. This creates a color list matching each point.

2. Step 2: Pass color list to plt.scatter with c parameter

   Using c=colors applies the color list to points correctly. Then plt.show() displays the plot.

3. Final Answer:

   colors = ['red' if val > 25 else 'blue' for val in y] plt.scatter(x, y, c=colors) plt.show() -> Option A

4. Quick Check:

   Use list comprehension for colors, pass as c=colors [OK]

Hint: Use list comprehension for colors, pass with c=colors [OK]

Common Mistakes:

• Using 'color' instead of 'c' parameter
• Passing single color string instead of list
• Checking condition on x instead of y