App Designer: Calling variables created in other functions

Hi!

I have a MATLAB code that works well when I run it in the command window. I'm creating an app for a better user experience.

The app takes inputs of X positions and Y positions in a 2D graph and plots a rectangular grid of points.

I have 2 edit fields where the user can enter the positions of the rows and columns. ( x positions = 1 2 3 4 or y positions = 5 6 7 8)

These inputs are converted in vectors. The code then uses the number of elements in each vector (ie number of rows and columns) to calculate and plot the points on a graph.

When I push the plot button, however, I get the message "Unrecognized method, property or field 'n' for class", which basically means that I'm not able to use the variable I've created in the Edit Field functions in the Button function. I know the basic algorithm works because I've tried it in MATLAB.

How do I solve this error? I've referred to the available documentation and I can see that I've adhered to syntax. Please help me out with this.

Thank you!

Answer 1

[Mehmed Saad]

The variable you are defining in

function YpositionsEditFieldValueChanged(app, event)
.
.   % y_converted
.
end

and

function XpositionsEditFieldValueChanged(app, event)
.
.   % x_converted
.
end

are all local variables and you cannot access them by app.XpositionsEditFieldValueChanged.x_converted

either generate app.x_converted (just like you generated app.x_pos and app.y_pos

or

pass this data in app.XpositionsEditFieldValueChanged UserData field

Have a look at code below

function XpositionsEditFieldValueChanged(app, event)
            x_input = app.XpositionsEditField.Value;    % User inputs X positions separated by space
            % Put x_converted in UserData
            app.XpositionsEditField.UserData.x_converted = str2double(strsplit(x_input,' ')); % Create vector with X positions
            % Put m in UserData
            app.XpositionsEditField.UserData.m = numel(app.XpositionsEditField.UserData.x_converted);  % Save number of columns of the grid in 'n' 
end

% Value changed function: YpositionsEditField
function YpositionsEditFieldValueChanged(app, event)
            y_input = app.YpositionsEditField.Value;   % User inputs Y positions separated by space
            app.YpositionsEditField.UserData.y_converted = str2double(strsplit(y_input,' ')); % Create vector with Y positions
            app.YpositionsEditField.UserData.m = numel(app.YpositionsEditField.UserData.y_converted);  % Save number of rows of the grid in 'm'        
end

% Button pushed function: PlotButton
function PlotButtonPushed(app, event)
            n_rows = app.XpositionsEditField.UserData.m;
            n_columns = app.YpositionsEditField.UserData.m;
% I dont know what you are trying to do here
            for j = n_columns
                for i = 1:1:n_rows
                    app.x_pos(i + n_rows*(j-1)) = app.XpositionsEditField.UserData.x_converted(i);
                end
                for k = 1:1:n_rows
                    if (j-1) < ((n_rows*(j-1) + k)/n_rows) <= (j+1)
                        app.y_pos(k + n_rows*(j-1)) = app.YpositionsEditField.UserData.y_converted(j);
                    end
                end
            end

            plot(app.UIAxes,0,0,'ko')
% Hold on axes 
            app.UIAxes.NextPlot = "add";
            plot(app.UIAxes,app.x_pos,app.y_pos,'r*')
end

Answer 2

[Cameron B]

This is what I came up with. I'm not sure if it's what you're after, but it looks like it could be. The first thing to learn about app designer is how to save and pass variables from function to function. You had the right idea, but I cleaned it up a bit. Keep in mind that these are saved as structures which is not necessary, but it does have some advantages.

    properties (Access = private)
        x_pos
        y_pos
    end


    % Callbacks that handle component events
    methods (Access = private)

        % Value changed function: XpositionsEditField
        function XpositionsEditFieldValueChanged(app, event)
            x_input = app.XpositionsEditField.Value;    % User inputs X positions separated by space
            app.x_pos.x_converted = str2double(strsplit(x_input,' ')); % Create vector with X positions
            app.x_pos.n = numel(app.x_pos.x_converted);  % Save number of columns of the grid in 'n' 
        end

        % Value changed function: YpositionsEditField
        function YpositionsEditFieldValueChanged(app, event)
            y_input = app.YpositionsEditField.Value;   % User inputs Y positions separated by space
            app.y_pos.y_converted = str2double(strsplit(y_input,' ')); % Create vector with Y positions
            app.y_pos.m = numel(app.y_pos.y_converted);  % Save number of rows of the grid in 'm'        
        end

        % Button pushed function: PlotButton
        function PlotButtonPushed(app, event)
            n_rows = app.x_pos.n;
            n_columns = app.y_pos.m;
            for j = n_columns
                for i = 1:1:n_rows
                    app.x_pos.xx(i + n_rows*(j-1)) = app.x_pos.x_converted(i);
                end
                for k = 1:1:n_rows
                    if (j-1) < ((n_rows*(j-1) + k)/n_rows) <= (j+1)
                        app.y_pos.yy(k + n_rows*(j-1)) = app.y_pos.y_converted(j);
                    end
                end
            end
            plot(app.UIAxes,0,0,'ko')
            hold(app.UIAxes,'on')
            plot(app.UIAxes,app.x_pos.xx,app.y_pos.yy,'r*')
        end
    end