The Project | About Us | Contribute | Donations | License
HOME My courses Completed
◄ Previous
◄

2D Plots

Next ►
►

In this section, we will explore how to create and customize 2D plots in MATLAB. Plotting data is a crucial aspect of data analysis and visualization, and MATLAB provides a wide range of functions to create various types of 2D plots.

Key Concepts

  1. Basic Plotting Functions
  2. Customizing Plots
  3. Multiple Plots in One Figure
  4. Annotations and Labels
  5. Saving Plots

  1. Basic Plotting Functions

plot Function

The plot function is the most commonly used function for creating 2D plots. It plots the data points defined by their x and y coordinates.

% Example: Basic Line Plot
x = 0:0.1:10; % x values from 0 to 10 with a step of 0.1
y = sin(x);   % y values as the sine of x
plot(x, y);   % create the plot
title('Sine Wave'); % add title
xlabel('x');  % label x-axis
ylabel('sin(x)'); % label y-axis

scatter Function

The scatter function creates a scatter plot with individual points.

% Example: Scatter Plot
x = rand(1, 50); % 50 random x values
y = rand(1, 50); % 50 random y values
scatter(x, y, 'filled'); % create the scatter plot with filled circles
title('Random Scatter Plot');
xlabel('x');
ylabel('y');

  1. Customizing Plots

Line Styles, Markers, and Colors

You can customize the appearance of your plots by specifying line styles, markers, and colors.

% Example: Customizing Line Style, Marker, and Color
x = 0:0.1:10;
y1 = sin(x);
y2 = cos(x);
plot(x, y1, '-r', 'LineWidth', 2); % red solid line with width 2
hold on; % hold the current plot
plot(x, y2, '--b', 'LineWidth', 2); % blue dashed line with width 2
hold off; % release the plot
title('Sine and Cosine Waves');
xlabel('x');
ylabel('y');
legend('sin(x)', 'cos(x)'); % add legend

Axis Limits and Ticks

You can set the limits and ticks of the axes to better control the display of your data.

% Example: Setting Axis Limits and Ticks
x = 0:0.1:10;
y = sin(x);
plot(x, y);
title('Sine Wave with Custom Axis Limits');
xlabel('x');
ylabel('sin(x)');
xlim([0 12]); % set x-axis limits
ylim([-1.5 1.5]); % set y-axis limits
xticks(0:2:12); % set x-axis ticks
yticks(-1.5:0.5:1.5); % set y-axis ticks

  1. Multiple Plots in One Figure

Using hold on and hold off

You can plot multiple datasets on the same figure using hold on and hold off.

% Example: Multiple Plots in One Figure
x = 0:0.1:10;
y1 = sin(x);
y2 = cos(x);
plot(x, y1, '-r'); % plot first dataset
hold on; % hold the current plot
plot(x, y2, '--b'); % plot second dataset
hold off; % release the plot
title('Sine and Cosine Waves');
xlabel('x');
ylabel('y');
legend('sin(x)', 'cos(x)');

Subplots

The subplot function allows you to create multiple plots in a single figure window.

% Example: Subplots
x = 0:0.1:10;
y1 = sin(x);
y2 = cos(x);

subplot(2, 1, 1); % create a 2x1 grid, access the first subplot
plot(x, y1);
title('Sine Wave');
xlabel('x');
ylabel('sin(x)');

subplot(2, 1, 2); % access the second subplot
plot(x, y2);
title('Cosine Wave');
xlabel('x');
ylabel('cos(x)');

  1. Annotations and Labels

Adding Text Annotations

You can add text annotations to your plots to highlight specific points or areas.

% Example: Adding Text Annotations
x = 0:0.1:10;
y = sin(x);
plot(x, y);
title('Sine Wave with Annotations');
xlabel('x');
ylabel('sin(x)');
text(5, 0, 'Midpoint', 'HorizontalAlignment', 'center'); % add text annotation

Adding Arrows

You can use the annotation function to add arrows and other shapes.

% Example: Adding Arrows
x = 0:0.1:10;
y = sin(x);
plot(x, y);
title('Sine Wave with Arrow');
xlabel('x');
ylabel('sin(x)');
annotation('arrow', [0.5, 0.7], [0.5, 0.8]); % add arrow annotation

  1. Saving Plots

Saving as Image Files

You can save your plots as image files using the saveas function.

% Example: Saving Plot as Image File
x = 0:0.1:10;
y = sin(x);
plot(x, y);
title('Sine Wave');
xlabel('x');
ylabel('sin(x)');
saveas(gcf, 'sine_wave.png'); % save the current figure as a PNG file

Saving as MATLAB Figures

You can also save your plots as MATLAB figure files using the savefig function.

% Example: Saving Plot as MATLAB Figure
x = 0:0.1:10;
y = sin(x);
plot(x, y);
title('Sine Wave');
xlabel('x');
ylabel('sin(x)');
savefig('sine_wave.fig'); % save the current figure as a MATLAB figure file

Practical Exercises

Exercise 1: Create a Line Plot

Task: Create a line plot of the function \( y = e^{-x} \cos(2\pi x) \) for \( x \) ranging from 0 to 5. Customize the plot with a green dashed line and add appropriate labels and title.

Solution:

x = 0:0.1:5;
y = exp(-x) .* cos(2 * pi * x);
plot(x, y, '--g', 'LineWidth', 2);
title('Damped Cosine Wave');
xlabel('x');
ylabel('y = e^{-x} \cos(2\pi x)');

Exercise 2: Create a Scatter Plot

Task: Create a scatter plot of 100 random points with x and y values between 0 and 1. Customize the points to be red and add appropriate labels and title.

Solution:

x = rand(1, 100);
y = rand(1, 100);
scatter(x, y, 'r', 'filled');
title('Random Scatter Plot');
xlabel('x');
ylabel('y');

Exercise 3: Create Subplots

Task: Create a figure with two subplots. The first subplot should be a line plot of \( y = \sin(x) \) and the second subplot should be a line plot of \( y = \cos(x) \) for \( x \) ranging from 0 to 2π.

Solution:

x = 0:0.1:2*pi;
y1 = sin(x);
y2 = cos(x);

subplot(2, 1, 1);
plot(x, y1);
title('Sine Wave');
xlabel('x');
ylabel('sin(x)');

subplot(2, 1, 2);
plot(x, y2);
title('Cosine Wave');
xlabel('x');
ylabel('cos(x)');

Conclusion

In this section, we covered the basics of creating and customizing 2D plots in MATLAB. We learned how to use the plot and scatter functions, customize plots with different line styles, markers, and colors, and create multiple plots in one figure using hold on and subplot. We also explored how to add annotations and save plots. These skills are essential for effectively visualizing and presenting data in MATLAB. In the next section, we will delve into 3D plots and explore how to visualize data in three dimensions.

◄ Previous
◄
Next ►
►
The Project | About Us | Contribute | Donations | License
© Copyright 2024. All rights reserved