Subplot for multiple panels in MATLAB - Deep Dive

Overview - Subplot for multiple panels

What is it?

Subplot is a way to divide a single figure window into multiple smaller sections, called panels, where each panel can display its own plot. This helps you compare different graphs side by side without opening many separate windows. You specify how many rows and columns of panels you want, and then fill each panel with a plot. It is very useful for showing related data or different views of the same data in one place.

Why it matters

Without subplot, you would need to open many separate figure windows to see multiple plots, which can be confusing and clutter your screen. Subplot lets you organize multiple graphs neatly in one window, making it easier to compare and analyze data visually. This saves time and helps you understand relationships between different datasets quickly.

Where it fits

Before learning subplot, you should know how to create basic plots in MATLAB. After mastering subplot, you can learn advanced figure customization, interactive plotting, and exporting multi-panel figures for reports or presentations.

Mental Model

Core Idea

Subplot splits one figure window into a grid of smaller panels, each holding its own plot, so you can see many graphs together in an organized way.

Think of it like...

Imagine a photo collage frame with multiple slots. Each slot holds a different photo, but all photos are visible together in one frame. Subplot is like that frame for your plots.

┌─────────────┬─────────────┐
│   Panel 1   │   Panel 2   │
├─────────────┼─────────────┤
│   Panel 3   │   Panel 4   │
└─────────────┴─────────────┘

Each box is a subplot panel inside one figure window.

Build-Up - 7 Steps

1

Foundation

Basic single plot creation

Concept: Learn how to create a simple plot in MATLAB.

Use the plot function to draw a graph. For example, plot a sine wave: x = linspace(0,2*pi,100); y = sin(x); plot(x,y); title('Sine Wave');

Result

A single figure window opens showing a smooth sine wave curve.

Understanding how to create a basic plot is essential before arranging multiple plots together.

2

Foundation

Understanding figure windows

Concept: Know that each plot appears in a figure window, which can hold one or more plots.

When you run plot commands, MATLAB opens a figure window to display the graph. By default, each plot command opens a new figure unless you specify otherwise.

Result

Multiple plot commands create multiple figure windows unless managed.

Recognizing that figure windows are containers for plots helps you see why organizing multiple plots in one window is useful.

3

Intermediate

Creating a 2x2 subplot grid

🤔Before reading on: do you think subplot(2,2,3) places the plot in the third row or third panel? Commit to your answer.

Concept: Learn to divide the figure into a grid of panels and place plots in specific panels.

Use subplot(m,n,p) where m=rows, n=columns, p=panel number: x = linspace(0,2*pi,100); subplot(2,2,1); plot(x,sin(x)); title('Panel 1'); subplot(2,2,2); plot(x,cos(x)); title('Panel 2'); subplot(2,2,3); plot(x,tan(x)); title('Panel 3'); subplot(2,2,4); plot(x,sqrt(x)); title('Panel 4');

Result

One figure window with 4 panels arranged in 2 rows and 2 columns, each showing a different plot.

Knowing how subplot numbers panels row-wise helps you control exactly where each plot appears.

4

Intermediate

Customizing subplot spacing

🤔Before reading on: do you think subplot automatically adjusts spacing between panels or do you need extra commands? Commit to your answer.

Concept: Learn to adjust space between subplot panels for better appearance.

By default, subplot panels can be cramped. Use 'tight_subplot' from File Exchange or adjust 'Position' property: h = subplot(2,2,1); pos = get(h,'Position'); set(h,'Position',[pos(1) pos(2)+0.05 pos(3) pos(4)-0.05]); Repeat for other panels or use built-in functions to control spacing.

Result

Panels have more space between them, making plots clearer and titles visible.

Adjusting subplot spacing improves readability and presentation quality of multi-panel figures.

5

Intermediate

Using subplot with different plot types

Concept: Combine different kinds of plots in subplot panels to compare data visually.

You can mix line plots, bar charts, scatter plots, etc. in subplot panels: subplot(2,2,1); plot(x,sin(x)); subplot(2,2,2); bar([1 3 2 4]); subplot(2,2,3); scatter(rand(10,1),rand(10,1)); subplot(2,2,4); pie([1 2 3]);

Result

One figure window with four different plot types arranged in panels.

Subplot lets you compare different visualizations side by side, enhancing data insight.

6

Advanced

Controlling subplot panel size precisely

🤔Before reading on: do you think subplot panels can have different sizes by default? Commit to your answer.

Concept: Learn to manually set subplot panel sizes and positions for custom layouts.

Use 'axes' function with 'Position' to create panels of any size: figure; axes('Position',[0.1 0.55 0.35 0.35]); plot(x,sin(x)); axes('Position',[0.55 0.55 0.35 0.35]); plot(x,cos(x)); axes('Position',[0.1 0.1 0.8 0.35]); plot(x,tan(x));

Result

Figure with three panels of different sizes and positions, not limited to grid layout.

Knowing how to control panel size and position breaks the grid limitation and allows flexible figure design.

7

Expert

Avoiding common subplot pitfalls in production

🤔Before reading on: do you think reusing subplot indices without clearing figures causes problems? Commit to your answer.

Concept: Understand how subplot handles figure state and how to avoid overwriting or cluttering plots in scripts.

Repeated calls to subplot with same indices overwrite previous plots unless figure is cleared or new figure created: figure(1); clf; subplot(2,2,1); plot(x,sin(x)); subplot(2,2,1); plot(x,cos(x)); % overwrites previous plot Use clf to clear or figure(n) to create new windows. Also, avoid tight loops creating many subplots without clearing to prevent memory issues.

Result

Clean, predictable multi-panel figures without accidental overwrites or clutter.

Understanding subplot's figure and axes management prevents bugs and messy visuals in complex scripts.

Under the Hood

MATLAB's subplot divides the figure window into a grid by calculating normalized positions for each panel. When you call subplot(m,n,p), it creates or activates an axes object positioned in the p-th grid cell. Internally, MATLAB manages these axes objects and redraws plots inside them. If you call subplot again with the same p, it activates that axes, allowing you to overwrite or add to the plot. The figure window holds all these axes as children, managing their layout and rendering.

Why designed this way?

Subplot was designed to provide a simple, intuitive way to organize multiple plots without complex manual positioning. The grid system matches common use cases of comparing data side by side. Alternatives like manual axes positioning exist but are more complex. The grid approach balances ease of use with flexibility, making it accessible for beginners and powerful enough for many applications.

Figure Window
┌─────────────────────────────────────┐
│                                     │
│  ┌─────────────┬─────────────┐      │
│  │   Axes 1    │   Axes 2    │      │
│  ├─────────────┼─────────────┤      │
│  │   Axes 3    │   Axes 4    │      │
│  └─────────────┴─────────────┘      │
│                                     │
└─────────────────────────────────────┘

Each Axes is a subplot panel managed by MATLAB inside the figure.

Myth Busters - 4 Common Misconceptions

Quick: Does subplot(2,2,3) place the plot in the third row? Commit to yes or no.

Common Belief: Many think subplot panel numbers count down columns first or represent rows directly.

Reality: Panel numbers count across rows first, left to right, then down rows.

Why it matters: Misunderstanding panel numbering causes plots to appear in unexpected positions, confusing analysis.

Quick: Does subplot automatically add space between panels? Commit to yes or no.

Common Belief: Some believe subplot always spaces panels nicely without overlap.

Reality: By default, subplot panels can be cramped with overlapping labels or titles.

Why it matters: Ignoring spacing leads to unreadable plots and poor presentation quality.

Quick: If you call subplot(2,2,1) twice, does it create two panels or overwrite? Commit to your answer.

Common Belief: People often think calling subplot with the same index creates a new panel each time.

Reality: It activates the existing panel, so the new plot overwrites the old one.

Why it matters: Not knowing this causes accidental plot overwrites and loss of data visualization.

Quick: Can subplot panels have different sizes by default? Commit to yes or no.

Common Belief: Some assume subplot panels can have different sizes automatically.

Reality: Subplot panels are equal-sized by default; different sizes require manual positioning.

Why it matters: Expecting automatic size differences leads to frustration and wasted time adjusting layouts.

Expert Zone

1

Subplot creates axes objects that can be further customized independently, allowing complex multi-panel figures with unique settings per panel.

2

Using 'hold on' inside a subplot panel lets you overlay multiple plots in the same panel, combining subplot with layered plotting.

3

The subplot grid numbering can be non-intuitive when using more than 10 panels because p is a single number, so careful indexing or loops are needed.

When NOT to use

Avoid subplot when you need highly customized or irregular panel layouts; instead, use manual axes positioning with 'axes' and 'Position' properties. For interactive dashboards, consider apps or specialized tools instead of static subplots.

Production Patterns

Professionals use subplot to create multi-panel figures for publications, combining different data views. They often automate subplot creation with loops and customize spacing and labels for clarity. In reports, subplot figures are exported as images or PDFs with consistent styling.

Connections

Grid Layout in Web Design

Subplot's grid of panels is similar to CSS grid layouts dividing a webpage into sections.

Understanding grid layouts in web design helps grasp how subplot arranges plots in rows and columns.

Dashboard Panels in Business Intelligence

Both subplot and BI dashboards organize multiple visualizations in one view for comparison.

Knowing dashboard design principles improves how you arrange subplot panels for effective data storytelling.

Modular Furniture Arrangement

Like arranging modular furniture pieces in a room for best use of space, subplot arranges plots efficiently.

This cross-domain view helps appreciate the importance of layout and spacing in visual organization.

Common Pitfalls

#1 Overwriting plots by calling subplot with the same panel index without clearing.

Wrong approach:

subplot(2,2,1); plot(x,sin(x));
subplot(2,2,1); plot(x,cos(x)); % overwrites previous plot

Correct approach:

figure; % create new figure
subplot(2,2,1); plot(x,sin(x));
subplot(2,2,1); plot(x,cos(x)); % overwrites in new figure or

subplot(2,2,1); plot(x,sin(x));
clf; % clear figure
subplot(2,2,1); plot(x,cos(x));

Root cause:

Misunderstanding that subplot activates existing axes and does not create new ones.

#2 Expecting subplot to automatically add enough space between panels for labels and titles.

Wrong approach:

subplot(2,2,1); plot(x,sin(x)); title('Sine');
subplot(2,2,2); plot(x,cos(x)); title('Cosine'); % titles overlap or are cut off

Correct approach:

Use tight_subplot function or manually adjust positions:
h = subplot(2,2,1);
pos = get(h,'Position');
set(h,'Position',[pos(1) pos(2)+0.05 pos(3) pos(4)-0.05]);

Root cause:

Assuming subplot manages spacing perfectly without manual adjustment.

#3 Trying to create subplot panels of different sizes using subplot function alone.

Wrong approach:

subplot(2,2,1); plot(x,sin(x));
subplot(2,2,2); plot(x,cos(x)); % both panels same size

Correct approach:

Use axes with custom Position:
axes('Position',[0.1 0.55 0.35 0.35]); plot(x,sin(x));
axes('Position',[0.55 0.55 0.4 0.35]); plot(x,cos(x));

Root cause:

Believing subplot supports unequal panel sizes by default.

Key Takeaways

Subplot divides one figure window into a grid of smaller panels, each holding its own plot for easy comparison.

Panel numbering in subplot counts across rows first, so knowing this helps place plots correctly.

By default, subplot panels are equal-sized and may need manual spacing adjustments for clarity.

Repeated calls to subplot with the same panel index overwrite existing plots unless the figure is cleared.

For flexible layouts beyond grids, manual axes positioning is necessary.