Title and axis labels in Matplotlib - Step-by-Step Execution

Concept Flow - Title and axis labels

Start plot

↓

Plot data points

↓

Add title with plt.title()

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Add x-axis label with plt.xlabel()

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Add y-axis label with plt.ylabel()

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Show plot with plt.show()

This flow shows how to create a plot, add a title, label the x and y axes, and then display the plot.

Execution Sample

Matplotlib

import matplotlib.pyplot as plt
x = [1, 2, 3]
y = [4, 5, 6]
plt.plot(x, y)
plt.title('My Plot')
plt.xlabel('X axis')
plt.ylabel('Y axis')
plt.show()

This code plots points, adds a title and axis labels, then displays the plot.

Execution Table

Step	Action	Function Called	Effect on Plot
1	Import matplotlib.pyplot	import matplotlib.pyplot as plt	Prepare plotting functions
2	Define x and y data	x = [1, 2, 3]; y = [4, 5, 6]	Data ready for plotting
3	Plot data points	plt.plot(x, y)	Line connecting points (1,4), (2,5), (3,6) shown
4	Add plot title	plt.title('My Plot')	Title 'My Plot' appears at top
5	Add x-axis label	plt.xlabel('X axis')	Label 'X axis' appears below x-axis
6	Add y-axis label	plt.ylabel('Y axis')	Label 'Y axis' appears beside y-axis
7	Display plot	plt.show()	Plot window opens showing all elements
8	End	N/A	Plot displayed with title and axis labels

💡 Plot is shown with title and axis labels, execution ends.

Variable Tracker

Variable	Start	After Step 2	After Step 3	Final
x	undefined	[1, 2, 3]	[1, 2, 3]	[1, 2, 3]
y	undefined	[4, 5, 6]	[4, 5, 6]	[4, 5, 6]
plt	undefined	matplotlib.pyplot module	matplotlib.pyplot module	matplotlib.pyplot module

Key Moments - 3 Insights

Why do we call plt.title() after plt.plot()?

Calling plt.title() after plt.plot() ensures the title is added to the current plot. The execution_table row 4 shows the title added after plotting data.

What happens if we forget plt.show()?

Without plt.show(), the plot window does not open to display the plot. Execution_table row 7 shows plt.show() triggers the plot display.

Can we add axis labels before plotting data?

Yes, but usually we plot data first to confirm axes exist. The flow shows adding labels after plotting for clarity.

Visual Quiz - 3 Questions

Look at the execution_table at step 4, what is the effect on the plot?

A A title 'My Plot' appears at the top

B X-axis label is added

C Data points are plotted

D Plot window opens

💡 Hint

Check the 'Effect on Plot' column at step 4 in execution_table

At which step does the plot window open to show the plot?

A Step 3

B Step 7

C Step 5

D Step 6

💡 Hint

Look for plt.show() call in the 'Function Called' column in execution_table

If we remove plt.ylabel('Y axis'), what changes in the plot?

A The plot will not show data points

B The plot title will disappear

C The plot will have no y-axis label

D The plot window will not open

💡 Hint

Refer to execution_table step 6 where y-axis label is added

Concept Snapshot

Use plt.title('Title') to add a plot title.
Use plt.xlabel('X label') and plt.ylabel('Y label') to label axes.
Call these after plt.plot() to label the current plot.
Use plt.show() to display the plot window.
Without plt.show(), plot won't appear.

Full Transcript

This lesson shows how to add a title and axis labels to a plot using matplotlib. First, we import matplotlib.pyplot as plt. Then, we define x and y data points. Next, we plot the data with plt.plot(x, y). After plotting, we add a title using plt.title('My Plot'). We label the x-axis with plt.xlabel('X axis') and the y-axis with plt.ylabel('Y axis'). Finally, plt.show() displays the plot window with all these elements. The execution table traces each step and its effect on the plot. Key moments clarify why the order matters and the role of plt.show(). The visual quiz tests understanding of these steps. The snapshot summarizes the commands and their purpose.