Labels, title, and legend in MATLAB - Step-by-Step Execution

Concept Flow - Labels, title, and legend

Create plot data

↓

Plot data on graph

↓

Add x-axis label

↓

Add y-axis label

↓

Add title

↓

Add legend

↓

Display complete graph

This flow shows how to create a plot, then add labels for x and y axes, a title, and a legend step-by-step.

Execution Sample

MATLAB

x = 1:5;
y = x.^2;
plot(x,y)
xlabel('X values')
ylabel('Y values')
title('Square Numbers')
legend('y = x^2')

This code plots y = x squared, then adds labels to the axes, a title, and a legend.

Execution Table

Step	Action	Effect on Plot	Output/Display
1	Create x and y data arrays	Data ready for plotting	No visible output
2	Plot x vs y	Graph with points/line appears	Graph window shows curve
3	Add xlabel 'X values'	X-axis labeled	X-axis shows label 'X values'
4	Add ylabel 'Y values'	Y-axis labeled	Y-axis shows label 'Y values'
5	Add title 'Square Numbers'	Title added on top	Title 'Square Numbers' appears above plot
6	Add legend 'y = x^2'	Legend box appears	Legend box shows 'y = x^2'
7	Display complete graph	All labels, title, legend visible	Final plot with all annotations

💡 All labels, title, and legend added; plot fully annotated and displayed

Variable Tracker

Variable	Start	After Step 1	After Step 2	After Step 7
x	undefined	[1 2 3 4 5]	[1 2 3 4 5]	[1 2 3 4 5]
y	undefined	[1 4 9 16 25]	[1 4 9 16 25]	[1 4 9 16 25]

Key Moments - 3 Insights

Why do we add xlabel and ylabel after plotting the data?

Because the plot must exist first to know where to place the labels; see execution_table steps 2 and 3.

What happens if we forget to add a legend?

The plot will show the data but no description of what the line or points represent; see execution_table step 6.

Can we add multiple legends for multiple lines?

Yes, by passing multiple strings to legend() matching each plotted line; this example shows one legend for one line.

Visual Quiz - 3 Questions

Look at the execution_table, what label is added at step 4?

A Y-axis label

B X-axis label

C Title

D Legend

💡 Hint

Check the 'Action' column at step 4 in execution_table

At which step does the plot first become visible?

A Step 1

B Step 2

C Step 3

D Step 6

💡 Hint

Look at 'Effect on Plot' column to see when graph appears

If we remove the legend command, what changes in the final plot?

A No title will show

B No axis labels will show

C No legend box will appear

D Plot will not display

💡 Hint

Refer to execution_table step 6 and 7 about legend presence

Concept Snapshot

plot(x,y) - draws the graph
xlabel('text') - labels x-axis
ylabel('text') - labels y-axis
title('text') - adds title
legend('label') - adds legend box
Add these after plotting for clear graphs.

Full Transcript

This example shows how to plot data in MATLAB and add labels, title, and legend. First, we create x and y data arrays. Then we plot y versus x. After the plot appears, we add an x-axis label with xlabel, a y-axis label with ylabel, a title with title, and a legend with legend. Each step updates the graph visually. The legend describes the plotted data line. Adding these elements helps make the graph easy to understand. The execution table traces each step and its effect on the plot. The variable tracker shows how x and y values remain the same after creation. Key moments clarify why labels come after plotting and the importance of the legend. The quiz tests understanding of when labels appear and what happens if the legend is missing.