Appending different size arrays each itteration in app desinger

I have an program which gets data from an oscilloscope and finds peaks in the signal, these peaks are stored in an private property called HoogtePulsen. And in one of the callbacks i want to put these peaks in an histogram.

        function TimerFcn_Callback2(app,~,~)
        %TimerFcn_Callback Timer callback function which executes periodically
        %  When LivePlotTimer is running this function does periodic waveform live plot updates
            y = app.HoogtePulsen.Value * 100;
            
            histogram(app.UIAxes_2,y,100,"BinLimits",463:464);
            
            
            drawnow
            
        end

This works fine, but i want to append the y value in an array every itteration of this callback. So i get an array of every peak found in all the measured signals of the oscilloscope. What is the easiest way to accomplish this in app desinger?

Answer 1

[Tim Koopman]

You could perhaps initialize a new property as an empty array and then append to this array with every iteration:

properties (Access = public)
      yourArray = [];
end

This section of code should be somewhere in the beginning of your code, before the callbacks that handle component events.

You then append to this array in your TimerFcn_Callback2 callback:

app.yourArray(end+1,1) = y;

[remco wouters]

properties (Access = public)
        AllePieken = []; % Description
        end
        

   function TimerFcn_Callback2(app,~,~)
        %TimerFcn_Callback Timer callback function which executes periodically
        %  When LivePlotTimer is running this function does periodic waveform live plot updates
            y = app.HoogtePulsen.Value * 100;
            app.AllePieken(end+1,1) = y;
            data = app.AllePieken.Value;
            histogram(app.UIAxes_2,data,100,"BinLimits",463:464);
            
            
            drawnow
            
   end
  

I now use this but it still doesn't work. Do you maybe know why?

[Tim Koopman]

Not totally sure without seeign the error message. My best guess is it is because app.AllePieken does not have a Value property.

Try using

data = app.AllePieken;

instead.

[remco wouters]

This worked perfect when i used cell arrays instead of normal arrays. Thank you for the help.

Answer 2

[Geoff Hayes]

remco - you could perhaps create a member variable for your App and then update that variable with the y on each call to the timer callback.

[remco wouters]

What do you mean with a member variable? I set a private property.

properties (Access = private)
        Allepieken           % Description
    end
    

And then i read the oscilloscope, and find the peaks in the signal.

     function TimerFcn_Callback(app,~,~)
        %TimerFcn_Callback Timer callback function which executes periodically
        %  When LivePlotTimer is running this function does periodic waveform live plot updates
            
            y = readWaveform(app.Oscilloscope)';
            acquisitionTime = app.Oscilloscope.AcquisitionTime;
            waveFormLength = app.Oscilloscope.WaveformLength;
            t = linspace(0, acquisitionTime, waveFormLength)';
            pks = findpeaks(y,'MinPeakHeight',app.LLD.Value);      
            app.AantalPulsen.Value = numel(pks);
            app.HoogtePulsen.Value = pks;
            plot(app.UIAxes, t, y)
            xlim(app.UIAxes, [t(1) t(end)])
            
            drawnow
            
     end
     
     

Then i want to plot these peaks and append new peaks found to already meassured peaks.

      function TimerFcn_Callback2(app,~,~)
        %TimerFcn_Callback Timer callback function which executes periodically
        %  When LivePlotTimer is running this function does periodic waveform live plot updates
            y = app.HoogtePulsen.Value * 100;
            histogram(app.UIAxes_2,y,100,"BinLimits",463:464);
            drawnow
            
        end
      

This works fine but, i want to append those y values in a array of all the meassured y values. I dont know how to append them to the Allepieken property. :(