Display different graphs from a dropdown menu

I want to be able to use a dropdown menu to display different graphs. I have been able to generate the graphs and the dropdown menu. However, when I go to use the dropdown menu I get an error which will be described below. Here is my code:

clear
clc

% create figure and components

fig = uifigure; 

ax = uiaxes('Parent', fig, 'Position', [10 10 400 400]);

% Create a plot

x = (-100:100)';
y.A = x.^2;
y.B = x.^3;
p = plot(ax, x, y.A);
p.YData = y.A;

% Create a dropdown component 

dd = uidropdown(fig, 'Position', [430 210 100 22],...
    'Items', {'A', 'B'},...
    'Value', 'A',...
    'ValueChangedFcn', @(dd, event) selection(dd,p));

% Create ValueChangedFcn callback

function selection(dd, p)
    val = dd.Value;
    p.YData = val;
    
end

The error that I get is as follows:

Value must be a vector of numeric type

Error in dropDownTest2>selection (line 29)
    p.YData = val;

Error in dropDownTest2>@(dd,event)selection(dd,p)
 
Error using matlab.ui.control.internal.controller.ComponentController/executeUserCallback (line 378)
Error while evaluating DropDown PrivateValueChangedFcn.

Thanks for your help

[Adam Danz]

What is the value of "val"?

[Nev Pires]

To be honest, I wanted val to be equal to whatever I selected from the dropdown menu. If "A" was selected, it would display the graph: y.A, and if "B" was selected it would display the graph: y.B. The only way I could get anything to display in the first place is with this code. I have no idea how to associate the dropdown menu selections with the respective graphs I want to plot.

Answer 1

[Adam Danz]

This should do what you're describing. Let me know if you have any questions.

% create figure and components
fig = uifigure; 
ax = uiaxes('Parent', fig, 'Position', [10 10 400 400]);
% Create a plot
x = (-100:100)';
y.A = x.^2;
y.B = x.^3;
p = plot(ax, x, y.A);
% p.YData = y.A;             %No need for this line
% Create a dropdown component 
dd = uidropdown(fig, 'Position', [430 210 100 22],...
    'Items', {'A', 'B'},...
    'Value', 'A',...
    'ValueChangedFcn', @(dd, event) selection(dd,p,y));
% Create ValueChangedFcn callback
function selection(dd, p, y)
switch dd.Value
    case 'A'
        val = y.A; 
    case 'B'
        val = y.B; 
    otherwise
        error('Did not recognize selection.')
end
    p.YData = val;
end