How to Update Legends as the for Goes on in MATLAB
In MATLAB, legends are a valuable component of data visualization that provides key information about different elements in a plot. They help viewers understand the meaning and context of each data series. However, there are situations where the data being plotted changes dynamically, and we need a way to update the legend to reflect these changes accurately.
This article will explore how to update legends as the for goes on in MATLAB.
Note: The phrase “updating legends as the for goes on in MATLAB” refers to the process of dynamically modifying and changing the legend in a MATLAB plot while a for loop is being executed.
What are Legends in MATLAB?
The legends in MATLAB serve as labels that describe the different elements or data series in a plot. They are commonly used in conjunction with multiple lines, scatter points, or bar graphs to distinguish and identify each data series. By default, legends are static and remain unchanged throughout the plotting process. However, there are techniques we can use to update legends dynamically, ensuring they accurately represent the evolving data.
Updating Legends as the for Goes on
To update the legend as the far goes on, we can follow the below-given steps:
Step 1: Initialize the Plot and Legend
First, we need to create an initial plot with the desired data series or values. The following example is used in this case that defines two data series (y1 & y2), and plot them against the x values. The legend function is used to assign labels to each data series.
x = 1:10;
y1 = x.^2;
y2 = 2*x;
figure;
plot(x, y1, 'ro-', x, y2, 'bs-');
legend('y = x^2', 'y = 2x');
The given code generates a plot with two lines representing different mathematical relationships, where the x values range from 1 to 10. The first series, y1 is obtained by squaring each x value, while the second series, y2 is obtained by doubling each x value. The first line in the plot is shown with red circles connected by solid lines, representing the relationship y = x^2. The second line is displayed with blue squares connected by solid lines, representing the relationship y = 2x and the information is displayed through legends.
Step 2: Update the Plot and Legend Dynamically
To demonstrate the dynamic updating of the plot and legend, we will use a for loop to modify the data series and update the plot accordingly.
for i = 1:5
y1 = y1 + 1;
y2 = y2 - 1;
plot(x, y1, 'ro-', x, y2, 'bs-');
legend('y = x^2 + 1', 'y = 2x - 1');
pause(1); % Pause for visualization purposes
end
Inside the loop, we increment y1 by 1 and decrement y2 by 1 to simulate changing data. Then, we update the plot using the plot function with the modified data series. The legend function is also called with updated labels to reflect the changes in the data. The pause function is used to visualize each update for 1 second.
The complete code for updating the legend as the for goes on is given below:
x = 1:10;
y1 = x.^2;
y2 = 2*x;
figure;
plot(x, y1, 'ro-', x, y2, 'bs-');
legend('y = x^2', 'y = 2x');
% Update the plot and legend dynamically
for i = 1:3
y1 = y1 + 1;
y2 = y2 - 1;
plot(x, y1, 'ro-', x, y2, 'bs-');
legend('y = x^2 + 1', 'y = 2x - 1');
pause(3); % Pause for visualization purposes
end
The above code modifies the y-values of both lines in each iteration of the for loop. The first line of the y-values increases by 1 and the y-values of the second line decrease by 1. After that, the plot and legend are updated to see the changes in the y-values. The first line is now labeled as “y = x^2 + 1” to indicate the increment, and the second line is labeled as “y = 2x – 1” to indicate the decrement. The code also uses the pause function to pause the code for 1 second after each update to allow you to see the changes in the plot.
If i=1 the output will be:
If i=2 the output will be:
If i=3 the output will be:
Elaboration of three steps is given below:
Conclusion
Updating legends as the for loop goes on is a useful technique when dealing with dynamic data. By following the step-by-step guide from this tutorial, you can easily update the legend in MATLAB and reflect the necessary changes in the plotted data.
Source: linuxhint.com