Axis limits (xlim, ylim) in Matplotlib - Cheat Sheet & Quick Revision

Recall & Review

beginner

What do xlim and ylim control in a matplotlib plot?

xlim controls the limits of the x-axis, and ylim controls the limits of the y-axis in a plot. They set the visible range of data on each axis.

beginner

How do you set the x-axis limits to 0 and 10 in matplotlib?

You use plt.xlim(0, 10) to set the x-axis limits from 0 to 10.

intermediate

What happens if you set ylim with the lower limit greater than the upper limit, like plt.ylim(10, 0)?

The y-axis will be inverted, so the values will decrease from top to bottom instead of increasing.

beginner

True or False: You can use ax.set_xlim() and ax.set_ylim() on an Axes object to set axis limits.

True. When working with an Axes object, you use ax.set_xlim() and ax.set_ylim() to set the axis limits.

beginner

Why might you want to set axis limits manually in a plot?

Setting axis limits manually helps focus on a specific data range, improves readability, or ensures consistent scales across multiple plots.

Which function sets the limits of the y-axis in matplotlib?

A plt.axis()

B plt.xlim()

C plt.ylim()

D plt.set_limits()

plt.ylim() sets the y-axis limits. plt.xlim() sets the x-axis limits.

What will plt.xlim(5, 0) do to the x-axis?

A Invert the x-axis from 5 to 0

B Ignore the command

C Cause an error

D Set x-axis limits from 0 to 5

Setting limits with the lower limit greater than the upper limit inverts the axis.

How do you reset axis limits to automatic scaling in matplotlib?

A plt.xlim() without arguments

B plt.xlim(auto=True)

C plt.xlim(None)

D plt.autoscale()

plt.autoscale() resets the axis limits to automatic scaling based on the data.

Which method is used to set axis limits on a specific Axes object named ax?

A ax.set_limits()

B ax.set_xlim() and ax.set_ylim()

C ax.axis_limits()

D ax.limits()

Use ax.set_xlim() and ax.set_ylim() to set limits on an Axes object.

Why is it useful to set axis limits manually?

A To zoom in on important data

B To make plots colorful

C To add grid lines

D To change plot title

Manual axis limits help focus on specific data ranges for better clarity.

Explain how to set and invert the x-axis limits in a matplotlib plot.

Think about how the order of limits affects axis direction.

Describe the difference between using plt.xlim() and ax.set_xlim() in matplotlib.

Consider the difference between pyplot and object-oriented approaches.

Practice

1. What does the function plt.xlim(0, 10) do in a matplotlib plot?

easy

A. Clears the current plot

B. Sets the y-axis limits from 0 to 10

C. Sets the x-axis limits from 0 to 10

D. Plots data points between 0 and 10 on x-axis

Solution

1. Step 1: Understand the function purpose

   plt.xlim() sets the limits of the x-axis in a plot.

2. Step 2: Analyze the arguments

   The arguments (0, 10) specify the minimum and maximum values for the x-axis.

3. Final Answer:

   Sets the x-axis limits from 0 to 10 -> Option C

4. Quick Check:

   plt.xlim(0, 10) = x-axis limits 0 to 10 [OK]

Hint: Remember xlim controls x-axis range, ylim controls y-axis [OK]

Common Mistakes:

• Confusing xlim with ylim
• Thinking it plots data points
• Assuming it clears the plot

2. Which of the following is the correct syntax to set y-axis limits from -5 to 5 in matplotlib?

easy

A. plt.ylim(-5, 5)

B. plt.xlim(-5, 5)

C. plt.axis(ymin=-5, ymax=5)

D. plt.set_ylim(-5, 5)

Solution

1. Step 1: Identify the function for y-axis limits

   The correct function to set y-axis limits is plt.ylim().

2. Step 2: Check the syntax

   The syntax plt.ylim(-5, 5) correctly sets the y-axis from -5 to 5.

3. Final Answer:

   plt.ylim(-5, 5) -> Option A

4. Quick Check:

   ylim(-5, 5) sets y-axis limits correctly [OK]

Hint: Use plt.ylim() for y-axis limits, not plt.xlim() [OK]

Common Mistakes:

• Using plt.xlim() for y-axis limits
• Using non-existent plt.set_ylim()
• Confusing plt.axis() parameters

3. What will be the x-axis limits after running this code?

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

medium

A. [1, 4]

B. [2, 3]

C. [0, 1]

D. [3, 4]

Solution

1. Step 1: Understand the plot and xlim call

   The plot has x values 0 to 3 by default (index of list). The call plt.xlim(2, 3) sets the x-axis limits explicitly from 2 to 3.

2. Step 2: Confirm the axis limits

   Because of plt.xlim(2, 3), the x-axis will only show values between 2 and 3.

3. Final Answer:

   [2, 3] -> Option B

4. Quick Check:

   plt.xlim(2, 3) sets x-axis limits to [2, 3] [OK]

Hint: xlim sets exact x-axis range regardless of data [OK]

Common Mistakes:

• Assuming default axis limits remain
• Confusing data values with axis limits
• Ignoring that x-axis is index by default

4. Identify the error in this code snippet:

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

medium

A. plt.show() is missing parentheses

B. plt.plot() missing x values

C. plt.xlim() requires three arguments

D. xlim limits are reversed; min should be less than max

Solution

1. Step 1: Check the xlim arguments

   The call plt.xlim(5, 1) sets the lower limit to 5 and upper limit to 1, which is reversed.

2. Step 2: Understand axis limit rules

   Axis limits must have the minimum value first and maximum second. Reversed limits cause unexpected behavior or warnings.

3. Final Answer:

   xlim limits are reversed; min should be less than max -> Option D

4. Quick Check:

   Lower limit must be less than upper limit in xlim [OK]

Hint: Always put smaller number first in xlim and ylim [OK]

Common Mistakes:

• Reversing min and max values in limits
• Thinking xlim needs three arguments
• Ignoring function call syntax

5. You have a scatter plot with x values ranging from 0 to 100 and y values from 0 to 50. You want to zoom in on the region where x is between 20 and 40 and y is between 10 and 30. Which code correctly sets these axis limits?

hard

A. plt.xlim(20, 40)
plt.ylim(10, 30)

B. plt.xlim(10, 30)
plt.ylim(20, 40)

C. plt.xlim([10, 30])
plt.ylim([20, 40])

D. plt.axis([10, 30, 20, 40])

Solution

1. Step 1: Identify correct axis limits for x and y

   The question states x between 20 and 40, y between 10 and 30.

2. Step 2: Match limits to correct functions

   plt.xlim(20, 40) sets x-axis limits, plt.ylim(10, 30) sets y-axis limits correctly.

3. Final Answer:

   plt.xlim(20, 40) plt.ylim(10, 30) -> Option A

4. Quick Check:

   Use xlim for x-axis, ylim for y-axis limits [OK]

Hint: Match xlim to x-axis range, ylim to y-axis range [OK]

Common Mistakes:

• Swapping x and y limits
• Using list brackets in xlim/ylim
• Using plt.axis with wrong order