How to set the legends using a Simulink plot, when the input data (a matrix) comes from the workspace

Question

Leizer 2024-4-26

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评论： Leizer 2024-4-30

% In the workspace, create a matrix T to be used by Simulink

T(1:5,1)=0:4;

T(1:5,2)=2;

T(1:5,3)=3;

% The T first column represents the time

% The T second column represents the fist variable values

% The T third column represents the second variable values

%==================

Now, using the Simulink

Selecting the source "From Workspace"

Setting T as the parameters Data

Setting sample time as -1

Setting to "Holdin Final value" from output, after final data

Conecting this source to a scope, it is possible to see the simulation result

As we have the name of each variable:

How to use this Names at the Simulink plot legend?

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Answer 1

Amish 2024-4-30

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在 MATLAB Online 中打开

Hi Leizer ,

The Simulink "Scope" block does not directly support adding legends based on matrix data input. However, there are a few workarounds that you can try to set legends in a Simulink plot.

Using MATLAB Function Block for Custom Plotting : Connect a "MATLAB Function" Block to the "From Workspace" block and write a custom function for plotting. The function may look like:

function plotData(u)
    % Assuming u is the matrix T imported from the workspace
    time = u(:,1); 
    data1 = u(:,2);
    data2 = u(:,3);
    % plot
    plot(time, data1, time, data2);
    legend('Variable 1', 'Variable 2');
    xlabel('Time');
    ylabel('Value');
    title('Simulation Results');
end

Post-Processing with MATLAB Script: This approch will use a MATLAB script for plotting and adding legends after the simulation completes. Log the plot after simulation and store in your workspace ("To Workspace" block). After the simulation, use the logged data in MATLAB to create plots.

Here are some documentation links for your reference:

https://www.mathworks.com/help/matlab/creating_plots/add-legend-to-graph.html

https://www.mathworks.com/help/matlab/ref/legend.html

Hope this helps!

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Leizer 2024-4-30

Dear Amish,

Thank you very much for your attention.

The main idea is really to use it while simulating.

I saw that if I put the name of each one of the variables as an input from a sybsystem, it may works.

In this case, notice that the Output Scope do no recognize the names.

But if I open an internal sybsystem scope, tle scope legend uses the names that I defined.

So, using the same simulation, but looking under the subsystem:

Thus, I belive that if I can set the input variable names as defined in the workspace (<Names> at the original question), it may works. But I still do not know how to do it to verify if it works.

Thanks again !!

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