Inverted axes in Matplotlib - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to invert the y-axis in the plot.

Matplotlib

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

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

Ainvert_yaxis

Binvert

Cinvert_axis

Dinvert_xaxis

Attempts:

3 left

💡 Hint

Common Mistakes

Using invert_xaxis() instead of invert_yaxis()

Using a non-existent method like invert_axis()

The method invert_yaxis() flips the y-axis direction in the plot.

2fill in blank

medium

Complete the code to invert the x-axis using the Axes object.

Matplotlib

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

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

Ainvert_yaxis

Bflip_xaxis

Cinvert_axis

Dinvert_xaxis

Attempts:

3 left

💡 Hint

Common Mistakes

Using invert_yaxis() when x-axis inversion is needed

Using a method that does not exist like flip_xaxis()

The invert_xaxis() method on the Axes object flips the x-axis direction.

3fill in blank

hard

Fix the error in the code to invert the y-axis correctly.

Matplotlib

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

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

Ainvert_axis

Binvert_xaxis

Cinvert_yaxis

Dinvertyaxis

Attempts:

3 left

💡 Hint

Common Mistakes

Misspelling the method name as invertyaxis

Using invert_axis which does not exist

The correct method to invert the y-axis is invert_yaxis(). Other options are either misspelled or incorrect.

4fill in blank

hard

Fill both blanks to create a dictionary comprehension that maps numbers to their squares only if the number is less than 4.

Matplotlib

squares = {x: x[1]2 for x in range(1, 6) if x [2] 4}

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

A**

B<

C>

D*

Attempts:

3 left

💡 Hint

Common Mistakes

Using multiplication (*) instead of exponentiation (**)

Using greater than (>) instead of less than (<)

The operator ** is used for exponentiation (power), and < is the less than comparison operator.

5fill in blank

hard

Fill all three blanks to create a dictionary comprehension that maps uppercase letters to their ASCII values only if the ASCII value is greater than 65.

Matplotlib

ascii_map = [1]: ord([3]) for [1] in 'ABCDEF' if ord([3]) [2] 65}

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

Aletter

B>

Dord

Attempts:

3 left

💡 Hint

Common Mistakes

Using inconsistent variable names

Using less than operator instead of greater than

We use letter as the variable name, > as the comparison operator, and letter inside ord() to get ASCII values.

Practice

1. What does the invert_xaxis() method do in a matplotlib plot?

easy

A. It changes the x-axis scale from linear to logarithmic.

B. It swaps the x-axis with the y-axis.

C. It hides the x-axis labels and ticks.

D. It reverses the direction of the x-axis, so values decrease from left to right.

Solution

1. Step 1: Understand the purpose of invert_xaxis()

   The method invert_xaxis() reverses the x-axis direction, making values decrease from left to right instead of increasing.

2. Step 2: Compare with other options

   Options A, C, and D describe different actions unrelated to axis inversion.

3. Final Answer:

   It reverses the direction of the x-axis, so values decrease from left to right. -> Option D

4. Quick Check:

   invert_xaxis() reverses x-axis direction [OK]

Hint: invert_xaxis() flips x-axis direction left to right [OK]

Common Mistakes:

• Confusing invert_xaxis() with changing scale
• Thinking it hides axis labels
• Assuming it swaps axes

2. Which of the following is the correct way to invert the y-axis in matplotlib?

easy

A. plt.invert_yaxis()

B. ax.axis.invert_y()

C. ax.invert_yaxis()

D. plt.axis('invert_y')

Solution

1. Step 1: Recall the correct syntax for axis inversion

   In matplotlib, axis inversion methods are called on the axis object, not directly on plt.

2. Step 2: Identify the correct method call

   The correct method is invert_yaxis() called on an axis object, typically named ax.

3. Final Answer:

   ax.invert_yaxis() -> Option C

4. Quick Check:

   Use ax.invert_yaxis() to invert y-axis [OK]

Hint: Call invert_yaxis() on axis object, not plt [OK]

Common Mistakes:

• Calling invert_yaxis() on plt instead of ax
• Using incorrect method names
• Trying to invert axis via plt.axis()

3. What will be the effect of the following code snippet?

import matplotlib.pyplot as plt
fig, ax = plt.subplots()
ax.plot([1, 2, 3], [10, 20, 30])
ax.invert_xaxis()
plt.show()

medium

A. The x-axis will display values from 3 to 1 left to right.

B. The x-axis will display values from 1 to 3 left to right.

C. The y-axis will be inverted, showing 30 to 10 bottom to top.

D. The plot will raise an error because invert_xaxis() is invalid.

Solution

1. Step 1: Analyze the code's axis inversion

   The code calls ax.invert_xaxis(), which reverses the x-axis direction.

2. Step 2: Understand axis direction after inversion

   Normally, x-axis goes from 1 to 3 left to right; after inversion, it goes from 3 to 1 left to right.

3. Final Answer:

   The x-axis will display values from 3 to 1 left to right. -> Option A

4. Quick Check:

   invert_xaxis() reverses x-axis values [OK]

Hint: invert_xaxis() flips x-axis values order [OK]

Common Mistakes:

• Thinking invert_xaxis() affects y-axis
• Assuming axis direction stays the same
• Believing invert_xaxis() causes error

4. Identify the error in this code that tries to invert the y-axis:

import matplotlib.pyplot as plt
fig, ax = plt.subplots()
ax.plot([1, 2, 3], [10, 20, 30])
plt.invert_yaxis()
plt.show()

medium

A. invert_yaxis() should be called on ax, not plt.

B. invert_yaxis() does not exist in matplotlib.

C. The plot function is missing axis inversion parameter.

D. plt.show() must be called before invert_yaxis().

Solution

1. Step 1: Check where invert_yaxis() is called

   The code calls invert_yaxis() on plt, which is incorrect.

2. Step 2: Correct usage of invert_yaxis()

   This method must be called on the axis object ax, not on the pyplot module plt.

3. Final Answer:

   invert_yaxis() should be called on ax, not plt. -> Option A

4. Quick Check:

   Call invert_yaxis() on ax object [OK]

Hint: Call invert_yaxis() on ax, not plt [OK]

Common Mistakes:

• Calling invert_yaxis() on plt instead of ax
• Assuming invert_yaxis() is a plt method
• Calling plt.show() before inversion

5. You want to plot temperature decreasing over time, but your data has time increasing left to right. How can you use inverted axes to show time decreasing from left to right and temperature increasing bottom to top? Choose the correct code snippet.

hard

A. ax.plot(time, temperature)
ax.invert_xaxis()
ax.invert_yaxis()

B. ax.plot(time, temperature)
ax.invert_xaxis()

C. ax.plot(time, temperature)
ax.invert_yaxis()

D. ax.plot(time, temperature)

Solution

1. Step 1: Understand the desired axis directions

   Time should decrease from left to right, so x-axis must be inverted. Temperature should increase bottom to top, so y-axis stays normal.

2. Step 2: Choose the correct inversion method

   Only ax.invert_xaxis() is needed to flip time axis; inverting y-axis would reverse temperature direction incorrectly.

3. Final Answer:

   ax.plot(time, temperature) ax.invert_xaxis() -> Option B

4. Quick Check:

   Invert x-axis only to reverse time direction [OK]

Hint: Invert only the axis that needs reversed direction [OK]

Common Mistakes:

• Inverting both axes unnecessarily
• Not inverting any axis
• Inverting y-axis instead of x-axis