Broken axes concept in Matplotlib - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of broken axes plot code

What will be the output of the following Python code using matplotlib's broken axes?

Matplotlib

import matplotlib.pyplot as plt
from brokenaxes import brokenaxes

fig = plt.figure(figsize=(6,4))
bax = brokenaxes(ylims=((0, 1), (3, 4)))
bax.plot([0, 1, 2, 3], [0.5, 0.7, 3.5, 3.8])
plt.show()

A A plot with two x-axis segments broken at 1 and 2, but continuous y-axis.

B A single continuous y-axis from 0 to 4 with all points plotted normally.

C A plot with two y-axis segments: one from 0 to 1 and another from 3 to 4, showing points connected across the break.

D A runtime error because brokenaxes does not support multiple y-axis limits.

💡 Hint

Broken axes allow you to skip ranges on an axis to focus on important data segments.

The brokenaxes function creates a plot with two separate y-axis ranges (0-1 and 3-4). The points are plotted accordingly, skipping the gap between 1 and 3.

❓ data_output

intermediate

Number of plotted points in broken axes

Given this code using brokenaxes, how many points will be visible on the plot?

Matplotlib

import matplotlib.pyplot as plt
from brokenaxes import brokenaxes

fig = plt.figure()
bax = brokenaxes(ylims=((0, 2), (5, 7)))
data_x = [0, 1, 2, 3, 4]
data_y = [1, 1.5, 3, 6, 6.5]
bax.plot(data_x, data_y)
plt.show()

A 2 points

B 3 points

C 5 points

D 4 points

💡 Hint

Points outside the broken y-axis limits are not shown.

The first two points (y=1, 1.5) fall within 0-2, and the last two (y=6, 6.5) within 5-7. The point at y=3 is outside both ranges and not shown, so 4 points are visible.

🔧 Debug

advanced

Identify the error in broken axes usage

What error will this code raise when trying to create a broken axes plot?

Matplotlib

import matplotlib.pyplot as plt
from brokenaxes import brokenaxes

fig = plt.figure()
bax = brokenaxes(xlims=((0, 2), (1, 3)))
bax.plot([0, 1, 2], [1, 2, 3])
plt.show()

A SyntaxError because of wrong tuple format

B ValueError due to overlapping x-axis limits

C No error, plot shows two broken x-axis segments

D TypeError because brokenaxes does not support xlims parameter

💡 Hint

Check if the axis limit ranges overlap or are invalid.

The x-axis limits overlap between (0,2) and (1,3), which is invalid and causes a ValueError.

🚀 Application

advanced

Use case for broken axes in data visualization

Which scenario best fits using broken axes in a plot?

A Displaying data with a large gap in y-values to focus on two separate ranges.

B Visualizing data with only one small range of values.

C Creating a pie chart to show proportions.

D Plotting continuous data with no gaps or outliers.

💡 Hint

Broken axes help when data has gaps or outliers that distort scale.

Broken axes are useful to skip large gaps in data ranges and focus on important segments.

🧠 Conceptual

expert

Effect of broken axes on data interpretation

What is a potential risk when using broken axes in plots?

A It can mislead viewers by visually compressing or skipping data ranges, hiding true differences.

B It always improves clarity without any drawbacks.

C It causes plots to be unreadable due to overlapping axis labels.

D It prevents plotting multiple lines on the same graph.

💡 Hint

Think about how skipping axis ranges affects perception.

Broken axes can hide gaps or differences in data, potentially misleading interpretation if not clearly indicated.

Practice

1. What is the main purpose of using broken axes in matplotlib plots?

easy

A. To skip unimportant data ranges and focus on key parts

B. To add 3D effects to the plot

C. To change the color scheme automatically

D. To animate the plot over time

Solution

1. Step 1: Understand the concept of broken axes

   Broken axes are used to skip over parts of the axis where data is not important or has large gaps.

2. Step 2: Identify the main purpose

   This helps to focus on important data ranges without showing the entire axis continuously.

3. Final Answer:

   To skip unimportant data ranges and focus on key parts -> Option A

4. Quick Check:

   Broken axes = skip gaps [OK]

Hint: Broken axes hide gaps to highlight important data [OK]

Common Mistakes:

• Thinking broken axes add 3D or animation
• Confusing broken axes with color changes
• Assuming broken axes zoom in automatically

2. Which of the following is the correct way to import the brokenaxes package to use brokenaxes(...) directly for creating broken axes plots?

easy

A. from brokenaxes import BrokenAxes

B. import brokenaxes as ba

C. from brokenaxes import brokenaxes

D. import matplotlib.brokenaxes as ba

Solution

1. Step 1: Recall the correct import syntax

   The brokenaxes package provides the brokenaxes function to create broken axes plots.

2. Step 2: Identify the correct import statement

   The correct way is from brokenaxes import brokenaxes to access the function directly.

3. Final Answer:

   from brokenaxes import brokenaxes -> Option C

4. Quick Check:

   Import brokenaxes function = from brokenaxes import brokenaxes [OK]

Hint: Import brokenaxes function directly from brokenaxes [OK]

Common Mistakes:

• Using capital 'BrokenAxes' instead of 'brokenaxes'
• Trying to import from matplotlib instead of brokenaxes
• Using wrong import syntax causing ImportError

3. What will the following code output?

from brokenaxes import brokenaxes
import matplotlib.pyplot as plt

bax = brokenaxes(ylims=((0, 2), (8, 10)))
bax.plot([0, 1, 2, 3], [1, 1.5, 9, 9.5])
plt.show()

medium

A. A plot with y-axis broken between 2 and 8 showing points near 1 and 9

B. A plot with continuous y-axis from 0 to 10

C. An error because ylims must be a single tuple

D. A plot with x-axis broken between 2 and 8

Solution

1. Step 1: Analyze the ylims parameter

   The ylims=((0, 2), (8, 10)) means the y-axis is broken to show two ranges: 0 to 2 and 8 to 10, skipping 2 to 8.

2. Step 2: Understand the plotted points

   The y-values are 1, 1.5, 9, and 9.5, which fit into the two visible y-axis ranges.

3. Final Answer:

   A plot with y-axis broken between 2 and 8 showing points near 1 and 9 -> Option A

4. Quick Check:

   ylims tuple of ranges = broken y-axis [OK]

Hint: ylims with tuples creates breaks on y-axis [OK]

Common Mistakes:

• Assuming y-axis is continuous without breaks
• Confusing x-axis and y-axis breaks
• Expecting an error from tuple ylims

4. Identify the error in this code snippet that tries to create broken axes:

from brokenaxes import brokenaxes
import matplotlib.pyplot as plt

bax = brokenaxes(xlims=(0, 2), (5, 7))
bax.plot([1, 6], [10, 20])
plt.show()

medium

A. plt.show() must be called before plot

B. plot function requires x and y to be the same length

C. BrokenAxes cannot be used with xlims parameter

D. xlims should be a tuple of tuples, not separate tuples

Solution

1. Step 1: Check the xlims argument syntax

   The code uses xlims=(0, 2), (5, 7) which is invalid syntax; it should be a single tuple containing tuples like xlims=((0, 2), (5, 7)).

2. Step 2: Confirm other parts are correct

   The plot call and plt.show() are correct; the error is only in xlims syntax.

3. Final Answer:

   xlims should be a tuple of tuples, not separate tuples -> Option D

4. Quick Check:

   xlims syntax = tuple of tuples [OK]

Hint: Use double parentheses for xlims tuple of ranges [OK]

Common Mistakes:

• Passing multiple tuples without enclosing in one tuple
• Mixing up xlims and ylims syntax
• Calling plt.show() too early

5. You have data with y-values clustered around 0-3 and 50-55, with a large gap in between. How would you create a broken y-axis to show both clusters clearly using brokenaxes?

hard

A. Plot two separate figures for each cluster

B. Use ylims=((0, 3), (50, 55)) when creating brokenaxes

C. Use xlims=((0, 3), (50, 55)) to break x-axis instead

D. Use ylims=(0, 55) to show full range without breaks

Solution

1. Step 1: Identify the axis to break

   The gap is in y-values, so the y-axis needs to be broken to skip the large gap between 3 and 50.

2. Step 2: Set ylims with two ranges

   Using ylims=((0, 3), (50, 55)) creates a broken y-axis showing both clusters clearly.

3. Final Answer:

   Use ylims=((0, 3), (50, 55)) when creating brokenaxes -> Option B

4. Quick Check:

   Broken y-axis = ylims tuple of ranges [OK]

Hint: Set ylims with two ranges to break y-axis gaps [OK]

Common Mistakes:

• Breaking x-axis instead of y-axis
• Using single continuous ylims hiding gap
• Plotting separate figures unnecessarily