How to load seperate .mat files using a drop down component in App Designer?

Question

I have separate .mat files, trials in a study, which consits of the same variables but the value change between files.

I want to use a drop-down component in MATLAB app designer to select a file, load its variables and display various plots.

Any ideas how I could do this? Thank you in advance.

I had been loading a single file as a property like this: var = load('Trial1.mat') This code worked.

So then I tried to use this layout to load the files using the drop down menu but it didn't work..

 function SelectFileDropDownValueChanged(app, event)
            value = app.SelectFileDropDown.Value;
            if strcmp(value,'Trial 1')
                var = load('Trial1.mat');
            elseif strcmp(value,'Trial 2')
                var = load('Trial2.mat');
            elseif strcmp(value,'Trial 3')
                var = load('Trial3.mat');
            elseif strcmp(value,'Trial 4')
                var = load('Trial4.mat');
            elseif strcmp(value,'Trial5')
                var = load('Trial5.mat');
            end

Any ideas how I could do this? Thanks in advance!

Answer 1

You can do it as follows:

Add a new property named var to the App class.

You can add a private (or public) property in the EDITOR tab of the Designer:

Change the property name to var (matching your code sample).

Properties code block:

properties (Access = private)
    var % Description: store loaded variables
end

Now var is a class member.
The App Designer is based on Object-Oriented MATLAB Programming.
Accessing var is possible only withing the code of the App class (because it's a private member).
Accessing var property is as follows: app.var (app is a reference to class' object).
Note that app is the first parameter of class methods (as in SelectFileDropDownValueChanged method).

Modified SelectFileDropDownValueChanged code:

% Value changed function: SelectFileDropDown
function SelectFileDropDownValueChanged(app, event)
    value = app.SelectFileDropDown.Value;

    if strcmp(value,'Trial 1')
        app.var = load('Trial1.mat');
    elseif strcmp(value,'Trial 2')
        app.var = load('Trial2.mat');
    elseif strcmp(value,'Trial 3')
        app.var = load('Trial3.mat');
    elseif strcmp(value,'Trial 4')
        app.var = load('Trial4.mat');
    elseif strcmp(value,'Trial5')
        app.var = load('Trial5.mat');
    end           
end