Axis limits (xlim, ylim) in Matplotlib - Step-by-Step Execution

Concept Flow - Axis limits (xlim, ylim)

Start Plot

↓

Plot Data Points

↓

Set x-axis limits with xlim

↓

Set y-axis limits with ylim

↓

Render Plot with new axis limits

↓

End

The plot starts with data points, then x and y axis limits are set, and finally the plot is rendered with these limits.

Execution Sample

Matplotlib

import matplotlib.pyplot as plt
plt.plot([1, 2, 3, 4], [10, 20, 25, 30])
plt.xlim(1, 3)
plt.ylim(15, 28)
plt.show()

This code plots points and sets the x-axis limits from 1 to 3 and y-axis limits from 15 to 28.

Execution Table

Step	Action	xlim Values	ylim Values	Effect on Plot
1	Plot points (1,10), (2,20), (3,25), (4,30)	None	None	Plot shows all points with default axis limits
2	Set x-axis limits with plt.xlim(1, 3)	(1, 3)	None	X-axis now shows from 1 to 3, points outside hidden
3	Set y-axis limits with plt.ylim(15, 28)	(1, 3)	(15, 28)	Y-axis now shows from 15 to 28, points outside hidden
4	Render plot with new limits	(1, 3)	(15, 28)	Plot displays points within these axis ranges
5	End	(1, 3)	(15, 28)	Plot window closes or stays open depending on environment

💡 Plot rendering completes with xlim (1,3) and ylim (15,28) applied

Variable Tracker

Variable	Start	After Step 2	After Step 3	Final
xlim	None	(1, 3)	(1, 3)	(1, 3)
ylim	None	None	(15, 28)	(15, 28)

Key Moments - 3 Insights

Why do some points disappear after setting xlim and ylim?

Points outside the set axis limits are not shown because xlim and ylim restrict the visible range, as seen in execution_table steps 2 and 3.

What happens if xlim or ylim are set before plotting data?

Setting limits before plotting still works, but the plot will adjust to those limits when data is added, similar to steps 2 and 3 before step 1.

Can xlim and ylim be set to reverse the axis direction?

Yes, by setting the lower limit higher than the upper limit (e.g., xlim(3,1)), the axis direction reverses, changing the plot view.

Visual Quiz - 3 Questions

Look at the execution table, what are the xlim values after step 2?

A None

B (15, 28)

C (1, 3)

D (10, 30)

💡 Hint

Check the 'xlim Values' column at step 2 in the execution_table.

At which step do both xlim and ylim have values set?

A Step 1

B Step 3

C Step 2

D Step 4

💡 Hint

Look for the first row where both 'xlim Values' and 'ylim Values' columns are not None.

If you set plt.xlim(3,1), how would the plot change compared to step 2?

A X-axis direction reverses, showing values from 3 down to 1

B No change, same as (1,3)

C Plot will error and not show

D Y-axis limits also reverse automatically

💡 Hint

Recall axis limits can reverse axis direction if lower limit is greater than upper limit.

Concept Snapshot

plt.xlim(left, right) sets x-axis limits.
plt.ylim(bottom, top) sets y-axis limits.
Limits restrict visible data range.
Points outside limits are hidden.
Limits can reverse axis direction if reversed.

Full Transcript

This visual execution shows how matplotlib's xlim and ylim functions control the visible range of a plot's axes. First, data points are plotted. Then, xlim is set to (1,3), restricting the x-axis to show only values between 1 and 3. Next, ylim is set to (15,28), restricting the y-axis similarly. The plot updates to show only points within these ranges. Variables xlim and ylim change from None to their set tuples. Key moments clarify why points disappear outside limits and how axis direction can reverse. The quiz tests understanding of these steps and effects.