How Matplotlib renders figures - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import the Matplotlib plotting module.

Matplotlib

import matplotlib.[1] as plt

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

Afigure

Bplot

Cpyplot

Dimage

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'plot' instead of 'pyplot' causes import errors.

Trying to import 'figure' directly is incorrect.

The pyplot module is the main interface for plotting in Matplotlib.

2fill in blank

medium

Complete the code to create a new figure object.

Matplotlib

fig = plt.[1]()

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

Ashow

Bfigure

Cplot

Ddraw

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'plot()' creates a plot but not a figure object.

Using 'show()' displays the plot but does not create a figure.

The figure() function creates a new figure object in Matplotlib.

3fill in blank

hard

Fix the error in the code to add a subplot to the figure.

Matplotlib

ax = fig.[1](111)

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

Aadd_subplot

Badd_subplots

Csubplots

Dsubplot

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'subplot' directly on figure causes attribute errors.

Using 'subplots' returns multiple axes, not a single subplot.

The correct method to add a subplot to a figure is add_subplot().

4fill in blank

hard

Fill both blanks to plot data and display the figure.

Matplotlib

ax.[1]([1, 2, 3], [4, 5, 6])
plt.[2]()

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

Aplot

Bshow

Cscatter

Ddraw

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'scatter' instead of 'plot' changes the plot type.

Using 'draw' instead of 'show' does not display the window.

Use plot() to draw the line plot and show() to display the figure.

5fill in blank

hard

Fill all three blanks to create a figure, add a subplot, and plot data.

Matplotlib

fig = plt.[1]()
ax = fig.[2](111)
ax.[3]([10, 20, 30], [1, 4, 9])

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

Afigure

Badd_subplot

Cplot

Dshow

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up 'add_subplot' and 'subplots'.

Forgetting to call 'plot()' on the axes object.

Create a figure with figure(), add a subplot with add_subplot(), and plot data with plot().

Practice

1. What is the first step Matplotlib takes when creating a plot?

easy

A. Add data points directly to the screen

B. Display the plot with plt.show()

C. Save the plot to a file automatically

D. Create a figure and axes to draw on

Solution

1. Step 1: Understand Matplotlib's drawing process

   Matplotlib starts by creating a figure and axes, which are the canvas and area to draw on.

2. Step 2: Identify the first action in plotting

   Before adding data or showing the plot, the figure and axes must exist to hold the plot.

3. Final Answer:

   Create a figure and axes to draw on -> Option D

4. Quick Check:

   First step = create figure and axes [OK]

Hint: Remember: figure and axes come before plotting data [OK]

Common Mistakes:

• Thinking plt.show() creates the plot
• Assuming data is drawn directly without axes
• Believing plot saves automatically without show

2. Which of the following is the correct way to display a Matplotlib figure?

easy

A. plt.show()

B. plt.draw()

C. plt.display()

D. plt.render()

Solution

1. Step 1: Recall the function to display plots

   Matplotlib uses plt.show() to open a window and display the figure.

2. Step 2: Check other options for correctness

   plt.draw() updates the figure but does not display it; plt.display() and plt.render() do not exist in Matplotlib.

3. Final Answer:

   plt.show() -> Option A

4. Quick Check:

   Display function = plt.show() [OK]

Hint: Use plt.show() to see your plot on screen [OK]

Common Mistakes:

• Using plt.draw() instead of plt.show()
• Trying plt.display() which is not a Matplotlib function
• Confusing plt.render() with other libraries

3. What will the following code display?

import matplotlib.pyplot as plt
fig, ax = plt.subplots()
ax.plot([1, 2, 3], [4, 5, 6])
plt.show()

medium

A. A figure with a line connecting points (1,4), (2,5), (3,6)

B. A blank figure with no lines

C. An error because plt.subplots() is incorrect

D. A scatter plot of points (1,4), (2,5), (3,6)

Solution

1. Step 1: Understand the code's plotting commands

   plt.subplots() creates figure and axes; ax.plot() draws a line connecting given points.

2. Step 2: Identify the plot type and output

   ax.plot() connects points with lines, so the figure shows a line through (1,4), (2,5), (3,6).

3. Final Answer:

   A figure with a line connecting points (1,4), (2,5), (3,6) -> Option A

4. Quick Check:

   ax.plot() draws lines through points [OK]

Hint: ax.plot() draws lines; scatter needs ax.scatter() [OK]

Common Mistakes:

• Thinking ax.plot() creates scatter points only
• Assuming plt.subplots() causes an error
• Expecting no lines without plt.show()

4. What is wrong with this code snippet?

import matplotlib.pyplot as plt
fig = plt.figure()
plt.plot([1, 2, 3], [4, 5, 6])
fig.show()

medium

A. plt.plot() cannot be used without axes

B. fig.show() does not display the plot; plt.show() is needed

C. plt.figure() must be called after plt.plot()

D. The lists have different lengths causing an error

Solution

1. Step 1: Analyze the display method used

   fig.show() is not the standard way to display plots; plt.show() is required to render the figure window.

2. Step 2: Check other parts for errors

   plt.plot() works without explicit axes; lists have equal length; plt.figure() order is correct.

3. Final Answer:

   fig.show() does not display the plot; plt.show() is needed -> Option B

4. Quick Check:

   Use plt.show() to display figures [OK]

Hint: Always end with plt.show() to display plots [OK]

Common Mistakes:

• Using fig.show() instead of plt.show()
• Thinking plt.plot() needs axes object
• Assuming list length mismatch causes error here

5. You want to create a figure with two side-by-side plots sharing the same y-axis. Which code correctly sets this up before plotting data?

hard

A. fig, (ax1, ax2) = plt.subplots(2, 2, sharey=True)

B. fig, ax = plt.subplots(2, 1, sharex=True)

C. fig, (ax1, ax2) = plt.subplots(1, 2, sharey=True)

D. fig = plt.figure()
ax1 = fig.add_subplot(121)
ax2 = fig.add_subplot(122)

Solution

1. Step 1: Understand subplot layout for side-by-side plots

   Side-by-side means 1 row and 2 columns, so plt.subplots(1, 2) is correct.

2. Step 2: Check sharing y-axis option

   sharey=True shares the y-axis between the two plots as required.

3. Step 3: Verify other options

   fig, ax = plt.subplots(2, 1, sharex=True) creates vertical plots sharing x-axis; fig = plt.figure() ax1 = fig.add_subplot(121) ax2 = fig.add_subplot(122) creates subplots but does not share y-axis; fig, (ax1, ax2) = plt.subplots(2, 2, sharey=True) creates 4 plots (2x2), not 2 side-by-side.

4. Final Answer:

   fig, (ax1, ax2) = plt.subplots(1, 2, sharey=True) -> Option C

5. Quick Check:

   Side-by-side = (1,2), share y-axis = sharey=True [OK]

Hint: Use plt.subplots(1, 2, sharey=True) for side-by-side shared y-axis [OK]

Common Mistakes:

• Confusing rows and columns in plt.subplots()
• Forgetting to set sharey=True for shared y-axis
• Using add_subplot without sharing axes