Multiple plots on same Axes (choosing from listbox) in app designer

I am trying to have multiple plots on same axis in app designer through selecting the varibale of intrest on Y axis from Listbox and displaying one plot at a time while clearing the data from the previous plots. The proble is, everytime I plot, it returns with one plot with variable selected first and doesn't work for the rest of the variables

Example for 2 pvariables is as under !

function PlotButtonPushed(app, event)
               
               xinput = app.XAxisListBox_3.Value;
               yinput = app.YAxisListBox.Value; 
               xdata = app.thj(:,1);
               legend(app.UIAxes);
               cla(app.UIAxes);
               hold(app.UIAxes,'on');
               
               %SO2 Plot
                    if strcmp(xinput, 'Time')   
                     ydata = app.Var(:,1);
                     plot(app.UIAxes,xdata,ydata,'-','DisplayName',app.YAxisListBox.Value);
                     xlabel(app.UIAxes,app.XAxisListBox_3.Value);
                     ylabel(app.UIAxes,app.YAxisListBox.Value);
                    end
               %XCB plot
                    if strcmp(xinput, 'Time')   
                     ydata = app.Var(:,2);
                     plot(app.UIAxes,xdata,ydata,'-','DisplayName',app.YAxisListBox.Value)
                     xlabel(app.UIAxes,app.XAxisListBox_3.Value);
                     ylabel(app.UIAxes,app.YAxisListBox.Value);
                    end 
        end

        % Button pushed function: ClearButton
        function ClearButtonPushed(app, event)
         cla(app.UIAxes);
        end

[Radu Andrei Matei]

I can't understand what your problem is

Answer 1

[Tridib]

Hi @Kashif NADEEM,

I understand that you want to display several plots on the same axis, but only one plot should be visible at a time. The plot shown will depend on which variable is selected for the y-axis from the listbox of available variables.

But, you are plotting the data twice because both ‘if strcmp(xinput, ‘Time’)’ blocks will always be true when ‘xinput’ is ‘Time’. Additionally, you are not using the ‘Y’ variable selected in the ‘ListBox’ to decide which column to plot on the Y-axis. Since your plotting logic is the same in both cases, you do not need two separate ‘if’ blocks; you can combine them and make the code more efficient and clear.

• Assume that ‘app.Var’ holds your ‘Y’ data, with each column representing a different variable, and ‘app.YAxisListBox.Items’ contains the names of these variables, such as 'SO2' or 'XCB'. The index of the variable selected in the ‘ListBox’ tells you which column from ‘app.Var’ you should plot on the Y-axis.
• Add the necessary buttons, axes, and listboxes, and give each one a suitable name. Update the items and values in both listboxes as needed.
• In the code view section, add the properties ‘thj’ and ‘Var’ by selecting the add property option under the editor tab.
• Add the following code in the startupFcn callback function, as you need to set data for these properties before using them in your callbacks:

            % Example data initialization
            app.thj = (1:100)'; % 100 time points
            app.Var = [rand(100,1), rand(100,1)]; % Two variables to plot
            app.YAxisListBox.Items = {'SO2', 'XCB'}; % Variable names
            app.XAxisListBox_3.Items = {'Time'}; % X axis name

• Add the following code for the PlotButton:

            % Getting selected X and Y variable names
            xinput = app.XAxisListBox_3.Value;
            yinput = app.YAxisListBox.Value; 
        
            % Getting X data (Assuming ‘Time’ is the first column)
            xdata = app.thj(:,1);
        
            % Finding the index of the selected Y variable
            yIndex = find(strcmp(app.YAxisListBox.Items, yinput));
            if isempty(yIndex)
                uialert(app.UIFigure, 'Selected Y variable not found.', 'Error');
                return;
            end
        
            % Getting the corresponding Y data
            ydata = app.Var(:, yIndex);
        
            % Clearing axes and plotting new data
            cla(app.UIAxes);
            plot(app.UIAxes, xdata, ydata, '-', 'DisplayName', yinput);
        
            % Labels
            xlabel(app.UIAxes, xinput);
            ylabel(app.UIAxes, yinput);
        
            % Legend
            legend(app.UIAxes, 'show');

Through this, you will be able to achieve the desired functionality.

For more help, refer to the following documentations:

strcmp: https://www.mathworks.com/help/matlab/ref/strcmp.html

find: https://www.mathworks.com/help/matlab/ref/find.html

Hope this helps!