Update data in uitable in second tab from button callback in first tab

Hi, I am new to Matlab and still getting the hang of building an app programmatically.

I would like to update the data in a uitable based on the information supplied in a "setup" tab. In this simple example, the user can either select to calculate weights based on the number of iterations or can enter the weights manually.

I have tried to methods:

• Create the uitable with a tag, use findobj to get the uitable and then set the data, but that returned an empty graphics place holder.
• Create the tab with the uitable first and then send the uitable as a parameter to the button callback. This is the code shown below.

Any help will be much appreciated!

function [weights, NIter, calcWeights] = simpleApp()

    function editFieldChanged(src)
        NIter=src.Value;
    end

    function checkBoxChanged(event)
        calcWeights=event.Value;
    end

    function parButtonPushed(src,event,tab)

        if calcWeights
            [weights] = repelem(1/NIter,NIter)';
            k=findobj('Tag', 'weights'); % Returns empty GraphicsPlacerHolder and then error
            tab.Data=weights; % No error but data is not updated in the second tab.
        end
    end

%% Main GUI function

   % Set default values
   calcWeights=false;
   NIter=10;

    fig = uifigure;
    fig.Position(4)=250;
    movegui(fig,'center');
    tabgp = uitabgroup(fig);
    tab1 = uitab(tabgp,"Title","Set Up");
    tab2= uitab(tabgp,"Title", "Weights");

    % Create second tab containing uitable
    
    g2 = uigridlayout(tab2, [1,1]);
    g2.RowHeight = {30};
    g2.ColumnWidth = {'fit'};

    test=zeros(NIter,1);

    t1w=array2table(test,"RowNames",string(linspace(1,NIter,NIter)), "VariableNames",{'Weight'});
    t11w=uitable(g2,"Data",t1w,'Tag','weights');
    t11w.ColumnEditable = repelem(~calcWeights,1);
    t11w.Layout.Row=2;
    t11w.Layout.Column=1;

    % Create first tab containing set up parameters
    
    g = uigridlayout(tab1,[3,2]);
    g.RowHeight = {22,22,22};
    g.ColumnWidth = {'fit',50};

    cbx=uicheckbox(g, "Text","Calculate weights?","Position",[10,10,500,22]);
    cbx.Layout.Row=1;
    cbx.Layout.Column=1;
    cbx.ValueChangedFcn = @(src,event) checkBoxChanged(event);

    lbltab1=uilabel(g,"Text","Number of iterations");
    lbltab1.Layout.Row=2;
    lbltab1.Layout.Column=1;
    
    eftab1=uieditfield(g,'numeric');
    eftab1.Layout.Row=2;
    eftab1.Layout.Column=2;
    eftab1.Value=NIter;
    eftab1.ValueChangedFcn = @(src,event) editFieldChanged(src);
    
    btab11=uibutton(g,'Text','Continue',"ButtonPushedFcn", @(src,event) parButtonPushed(t11w));
    btab11.Layout.Row=3;
    btab11.Layout.Column = 1;

end

Answer 1

[Harald]

Hi,

to be honest, I am not sure why your code line returns the empty graphics placeholder. A fix however would be:

k=findobj(fig, 'Tag', 'weights')

Also if that's what you intend, be sure to use that object in the next line:

k.Data=weights;

Personally, I find it a lot easier to use App Designer. If you want to get started with it, take this free Onramp:

https://matlabacademy.mathworks.com/details/app-building-onramp/orab

Best wishes,

Harald

[Old Newbie]

Thank you - your solution worked and is neater than my "fix".

The layout of the actual app that I am building depends on user inputs so I am finding it easier to do it programmatically. However, I will go through the Onramp and see if I can do the same with the App Designer.

Answer 2

[Old Newbie]

I have figured it out - silly mistake on my side. Leaving the answer here in case it helps someone else battling with the same problem.

When I send the parameters to the callback, I only sent one parameter, while the callback function expected 3, so the callback function took the first parameter as the table to change. A simple change to set src.Data=weights rather than tab.Data=weights worked.

function [weights, NIter, calcWeights] = simpleApp()

    function editFieldChanged(src)
        NIter=src.Value;
    end

    function checkBoxChanged(event)
        calcWeights=event.Value;
    end

    function parButtonPushed(src)

        if calcWeights
            [weights] = repelem(1/NIter,NIter)';
            k=findobj('Tag', 'weights');
            src.Data=weights;
        end
    end
%% Main GUI function

   % Set default values
   calcWeights=false;
   NIter=10;

    fig = uifigure;
    fig.Position(4)=250;
    movegui(fig,'center');
    tabgp = uitabgroup(fig);
    tab1 = uitab(tabgp,"Title","Set Up");
    tab2= uitab(tabgp,"Title", "Weights");

    g2 = uigridlayout(tab2, [1,1]);
    g2.RowHeight = {30};
    g2.ColumnWidth = {'fit'};

    test=zeros(NIter,1);

    t1w=array2table(test,"RowNames",string(linspace(1,NIter,NIter)), "VariableNames",{'Benchmark Weight'});
    t11w=uitable(g2,"Data",t1w,'Tag','weights');
    t11w.ColumnEditable = repelem(~calcWeights,1);
    t11w.Layout.Row=2;
    t11w.Layout.Column=1;

    g = uigridlayout(tab1,[3,2]);
    g.RowHeight = {22,22,22};
    g.ColumnWidth = {'fit',50};

    cbx=uicheckbox(g, "Text","Calculate weights?","Position",[10,10,500,22]);
    cbx.Layout.Row=1;
    cbx.Layout.Column=1;
    cbx.ValueChangedFcn = @(src,event) checkBoxChanged(event);

    lbltab1=uilabel(g,"Text","Number of iterations");
    lbltab1.Layout.Row=2;
    lbltab1.Layout.Column=1;
    
    eftab1=uieditfield(g,'numeric');
    eftab1.Layout.Row=2;
    eftab1.Layout.Column=2;
    eftab1.Value=NIter;
    eftab1.ValueChangedFcn = @(src,event) editFieldChanged(src);
    
    btab11=uibutton(g,'Text','Continue',"ButtonPushedFcn", @(src,event) parButtonPushed(t11w));
    btab11.Layout.Row=3;
    btab11.Layout.Column = 1;

end