combing two arrays into a table (app designer)-Array indices must be positive integers or logical values.

I am trying to show to arrays in a table on app designer however, it keeps returning the error 'Array indices must be positive integers or logical values.' I have initialised the arrays as properties in order to call on them in the app, I susspect this is where I have gone wrong as the code is executing as if app.out_ff and app.Ef are empty. How can I resolve this? Thanks in advance!

 %initialising:
properties (Access = public)
        Property % Description
        out_ff
        Eff
    end
    
    methods (Access = public)
        
        function results = func(app)
            app.out_ff = out_f;
            app.Eff = Ef;
        end
        end
        
%getting file and creating table:
        [filename,Directory] = uigetfile('*.txt'); 
    rawData = readtable(filename); 
    app.UITable.Data = table(app.out_ff, app.Eff(length(app.out_ff))); % error source
    app.UITable.Data.Properties.VariableNames{1} = 't';
    app.UITable.Data.Properties.VariableNames{2} = 'Ef';
    app.UITable.ColumnName = app.UITable.Data.Properties.Variable
    
%the functions that produce the arrays:   
 function [output] = readdatav4 (input)
    t = rawData{:,1};
    Et = rawData{:,2};
    n_s = 0.063;
    p = 4.9;
    [w_c,Amp_noisef,w,app.Eff]= get_noise(t,Et,n_s,p);
    w_c;
end


function [w_c,Amp_noisef,w,Ef] = get_noise(t,Et,n_s,p)
    w= [1:length(t)]./(t(end)-t(1)); % Natural Frequency
    Ef=abs(fft(Et)); % Spectrum
    window=round(length(w).* n_s); % Window
    [out_f,out_Ef]=SmoothingSpec(w,Ef,window); % Smoothing
    w0=linspace(1,5,length(out_f));
    Ef_cube=out_Ef.*(w0.^p); % smooth spectra times w^p
    [M3,iM3] = max(out_Ef);
    [m3,im3] = min(Ef_cube(iM3+1:end)); % Find min
    Amp_noisef = out_Ef(im3+iM3); % noise floor amplitude
    w_c = out_f(im3+iM3); % Cuttoff frequency 
            [out_f,out_Ef]=SmoothingSpec(w,Ef,window); % Smoothing
end


function [out_w,out_Ef]=SmoothingSpec(w,Ef,window)
    if rem(length(Ef),2)==0 % case even data size
        sz=size(Ef);
    else
        sz=size(Ef)+1; % case odd data size
    end

    z=sz(1)/2; % keep positive frequencies
    for i=1:z-window
        out_Ef(i)=mean(Ef(i:i+window)); % smooth
    end
    out_w=w(1:z-window); % length cut for w
end

[Jonas]

i guess

length(out_ff)

gives 0, since it is not set at the start of the app (size 0x0 probably)

there effectively, there is written

app.Eff(0)

which gives the indexing error

Answer 1

[Kevin Holly]

Here are a few options to consider below.

1. Define variables

You can define variables when they are created as properties

properties (Access = public)
    out_ff = zeros(10,1)
    Eff = zeros(10,1)
end

2. Use an if condition that only ruins lines with both variables are not empty

if ~isempty(app.out_ff) && ~isempty(app.Eff)
    app.UITable.Data = table(app.out_ff, app.Eff(length(app.out_ff))); % error source
    app.UITable.Data.Properties.VariableNames{1} = 't';
    app.UITable.Data.Properties.VariableNames{2} = 'Ef';
    app.UITable.ColumnName = app.UITable.Data.Properties.Variable
else
    % Alternative
end

3. Use a try catch

try
    app.UITable.Data = table(app.out_ff, app.Eff(length(app.out_ff))); % error source
    app.UITable.Data.Properties.VariableNames{1} = 't';
    app.UITable.Data.Properties.VariableNames{2} = 'Ef';
    app.UITable.ColumnName = app.UITable.Data.Properties.Variable
catch
    % Alternative
end

[Gregor]

Thank you for your response! I have tried the if condition and catch method but the app just returns an empty table. I seems its reading the arrays as if they are empty as they are only defined within the function. If I try define them in properties it defines them as empty because the only way I can call on the array is within the function. Do you have any tips for how can I get around this?

[Kevin Holly]

To be clear, are you including app as an input variable for each function you have added?

Is it possible that you can attach the app, so I can clearly see the issue?

[Gregor]

Hi Kevin, apologies for the late response. I've attached the app to this comment. I have made some changes since I posted my question however I am still having the exact same problem. I have now included app as an input variable for each function however, the arrays are still returning empty. I have tested my code for reading the input data so its definitley recieving it but the functions dont seem to be transforming it. Thank you very much for your help and advice!

[Kevin Holly]

Please see app attached

[Gregor]

This worked perfectly thank you so much Kevin!