How do I pass data between functions in MATLAB App Designer?

I cannot get the syntax correct for passing data between functions using App Designer.

I have tried to follow the instructions in the article "Share Data within App Designer Apps" and can read in and plot data with the LoadHctdataButtonPushed function below.

However, when I invoke the function "BeginoptimizationButtonPushed" below, the value of the data (t, for example) is empty.

I can't see what I am doing differently from the example in the article. Any advice will be greatly appreciated!

Thanks,

Andy

-------------------------------------------------------

properties (Access = public)

t % time vector data

hct % hematocrit data

juf % ultra filtration data

% initial conditions

Vp0

Cp0

Vi0

Ci0

end

% Callbacks that handle component events

methods (Access = private)

% Callback function: LoadHctdataButton, UIAxes

function LoadHctdataButtonPushed(app, event)

filename=uigetfile;%; asks for data file

load(filename);% loads in t, hct(t) and juf(t) and initial SV values

yyaxis(app.UIAxes,'left')

plot(app.UIAxes,t,hct)

yyaxis(app.UIAxes,'right')

plot(app.UIAxes,t,juf,"Color",'r','LineWidth',2);

ylabel(app.UIAxes,'Juf (ml/min)')

app.Vp0EditField.Value=Vp0;

app.Cp0EditField.Value=Cp0;

app.Vi0EditField.Value=Vi0;

app.Ci0EditField.Value=Ci0;

app.NpointsEditField.Value=length(t);

end

% Button pushed function: BeginoptimizationButton

function BeginoptimizationButtonPushed(app, event)

t=app.t;

hct=app.hct;

juf=app.juf;

Vp0=app.Vp0;

Cp0=app.Cp0;

Vi0=app.Vi0;

Ci0=app.Ci0;

Answer 1

[Voss]

load(filename) creates variables in a workspace (i.e., a function's workspace or the base workspace - in this case the workspace is the LoadHctdataButtonPushed function's workspace).

load(filename) does not set any app properties (even if the app has properties with the same name as the variables loaded).

S = load(filename) stores the variables in a struct S. You can then loop over the fields of S (i.e., the loaded variables), and set the corresponding app property (if it exists) to the same value.

Something like this:

function LoadHctdataButtonPushed(app, event)
    
    [filename,filepath] = uigetfile(); %; asks for data file
    
    if isequal(filename,0) % return if user cancelled
        return
    end
    
    % load to struct S, and loop over fields of S, setting app properties
    % when they exist to the values in S.
    S = load(fullfile(filepath,filename));
    fn = fieldnames(S);
    for ii = 1:numel(fn)
        if isprop(app,fn{ii})
            app.(fn{ii}) = S.(fn{ii});
        end
    end
    
    % then use the app properties here:
    yyaxis(app.UIAxes,'left')
    plot(app.UIAxes,app.t,app.hct)
    yyaxis(app.UIAxes,'right')
    plot(app.UIAxes,app.t,app.juf,"Color",'r','LineWidth',2);
    ylabel(app.UIAxes,'Juf (ml/min)')
    app.Vp0EditField.Value=app.Vp0;
    app.Cp0EditField.Value=app.Cp0;
    app.Vi0EditField.Value=app.Vi0;
    app.Ci0EditField.Value=app.Ci0;
    app.NpointsEditField.Value=length(app.t);
    
end

[Andrew]

Thank you, Voss--this works well and I learned something! Very much appreciated.

Andy

[Voss]

You're welcome!