Fig, ax = plt.subplots pattern in Matplotlib - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a figure and axes using plt.subplots.

Matplotlib

fig, ax = plt.[1]()

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

Afigure

Bplot

Csubplots

Dshow

Attempts:

3 left

💡 Hint

Common Mistakes

Using plt.plot() instead of plt.subplots()

Using plt.figure() which returns only the figure, not axes

Trying to call plt.show() here which displays the plot

The plt.subplots() function creates a figure and axes objects together.

2fill in blank

medium

Complete the code to plot a line on the axes object.

Matplotlib

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

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

Aplot

Bscatter

Chist

Dbar

Attempts:

3 left

💡 Hint

Common Mistakes

Using ax.scatter() which draws points, not lines

Using ax.hist() which draws histograms

Using ax.bar() which draws bar charts

The ax.plot() method draws a line plot on the axes.

3fill in blank

hard

Fix the error in the code to set the title of the axes.

Matplotlib

fig, ax = plt.subplots()
ax.set_[1]('My Plot Title')

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

Aylabel

Btitle

Cxlabel

Dlegend

Attempts:

3 left

💡 Hint

Common Mistakes

Using set_xlabel or set_ylabel which label axes, not title

Using set_legend which controls the legend

The method ax.set_title() sets the title of the plot.

4fill in blank

hard

Fill both blanks to create a dictionary comprehension that maps words to their lengths if length is greater than 3.

Matplotlib

lengths = {word: [1] for word in words if len(word) [2] 3}

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Alen(word)

B>

C<

Dword

Attempts:

3 left

💡 Hint

Common Mistakes

Using < instead of > in the condition

Mapping word to word instead of length

Using len(word) in the condition but not in the value

The dictionary comprehension maps each word to its length if the length is greater than 3.

5fill in blank

hard

Fill all three blanks to create a dictionary comprehension that maps uppercase words to their values if the value is greater than 0.

Matplotlib

result = { [1]: [2] for k, v in data.items() if v [3] 0 }

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

Ak.upper()

Bv

C>

Dk

Attempts:

3 left

💡 Hint

Common Mistakes

Using original key without uppercasing

Using wrong comparison operator like <

Using key instead of value in the dictionary values

This comprehension creates a dictionary with keys as uppercase versions of original keys and values where the value is positive.

Practice

1. What does the variable fig represent when you write fig, ax = plt.subplots() in matplotlib?

easy

A. The specific plot area where data is drawn

B. The whole figure container that holds all plot elements

C. A list of all plots in the figure

D. The title of the plot

Solution

1. Step 1: Understand the role of fig in plt.subplots()

   The fig variable holds the entire figure container, which can include multiple plots, titles, legends, and other elements.

2. Step 2: Differentiate fig from ax

   The ax variable is the specific plot area inside the figure where data is drawn, not the whole container.

3. Final Answer:

   The whole figure container that holds all plot elements -> Option B

4. Quick Check:

   fig = whole figure container [OK]

Hint: Remember: fig = full figure, ax = plot area [OK]

Common Mistakes:

• Confusing fig with ax as the plot area
• Thinking fig is just the plot title
• Assuming fig is a list of plots

2. Which of the following is the correct syntax to create a figure and axes using matplotlib's plt.subplots()?

easy

A. plt.subplots = fig, ax

B. fig = plt.subplots(ax)

C. ax, fig = plt.subplots()

D. fig, ax = plt.subplots()

Solution

1. Step 1: Recall the correct unpacking syntax

   The function plt.subplots() returns two objects: the figure and the axes. The correct way to capture them is fig, ax = plt.subplots().

2. Step 2: Check each option for syntax correctness

   fig = plt.subplots(ax) tries to pass ax as an argument incorrectly. ax, fig = plt.subplots() reverses the order, which is wrong. plt.subplots = fig, ax tries to assign incorrectly.

3. Final Answer:

   fig, ax = plt.subplots() -> Option D

4. Quick Check:

   Correct unpacking = fig, ax = plt.subplots() [OK]

Hint: Remember: fig first, then ax from plt.subplots() [OK]

Common Mistakes:

• Swapping fig and ax order
• Passing ax as argument to plt.subplots()
• Incorrect assignment syntax

3. What will be the output type of ax after running this code?

import matplotlib.pyplot as plt
fig, ax = plt.subplots()

medium

A.

B.

C.

D.

Solution

1. Step 1: Understand what plt.subplots() returns

   The function returns a figure object and an axes object. The axes object is usually an instance of AxesSubplot class.

2. Step 2: Identify the type of ax

   After unpacking, ax is the axes object, which is of type matplotlib.axes._subplots.AxesSubplot.

3. Final Answer:

   <class 'matplotlib.axes._subplots.AxesSubplot'> -> Option A

4. Quick Check:

   ax type = AxesSubplot [OK]

Hint: ax is the plot area object, not the figure [OK]

Common Mistakes:

• Confusing ax type with fig type
• Thinking ax is a list or tuple
• Assuming ax is a string or number

4. Identify the error in this code snippet:

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

medium

A. fig and ax are reversed in assignment

B. ax.plot() arguments are incorrect

C. Missing parentheses after plt.subplots

D. plt.show() is called before plotting

Solution

1. Step 1: Check the call to plt.subplots

   The code uses plt.subplots without parentheses, so it assigns the function itself, not its result.

2. Step 2: Understand the impact on ax.plot

   Since fig, ax are assigned incorrectly, ax is a function, not an axes object, so ax.plot() will cause an error.

3. Final Answer:

   Missing parentheses after plt.subplots -> Option C

4. Quick Check:

   Call plt.subplots() with () [OK]

Hint: Always add () to call plt.subplots function [OK]

Common Mistakes:

• Forgetting parentheses on plt.subplots
• Mixing up fig and ax variables
• Calling plt.show() too early

5. You want to create a figure with 2 rows and 1 column of plots using plt.subplots(). Which code correctly creates the figure and axes, and plots a line on the second subplot?

hard

A. fig, ax = plt.subplots(2, 1)
ax[1].plot([1, 2, 3], [3, 2, 1])

B. fig, ax = plt.subplots(1, 2)
ax[2].plot([1, 2, 3], [3, 2, 1])

C. fig, ax = plt.subplots(2, 1)
ax.plot([1, 2, 3], [3, 2, 1])

D. fig, ax = plt.subplots(2)
ax[0].plot([1, 2, 3], [3, 2, 1])

Solution

1. Step 1: Create figure with 2 rows and 1 column

   Use plt.subplots(2, 1) to create 2 vertical subplots. This returns ax as an array of axes.

2. Step 2: Plot on the second subplot

   Access the second subplot with ax[1] (indexing starts at 0) and call plot() on it.

3. Final Answer:

   fig, ax = plt.subplots(2, 1) ax[1].plot([1, 2, 3], [3, 2, 1]) -> Option A

4. Quick Check:

   2 rows, 1 col = plt.subplots(2,1), plot on ax[1] [OK]

Hint: Use ax[index] for multiple subplots, index starts at 0 [OK]

Common Mistakes:

• Using wrong subplot shape (1,2) instead of (2,1)
• Trying to plot on ax without indexing when multiple axes exist
• Using invalid index like ax[2] when only 2 subplots exist