Unable to use the list box items as a UIAxes legend values in App Designer

I have built an application that plots data from items selected from a listbox. The listbox has multi-select enabled so I can plot multiple items.

When I use the below code, the default legend item names are "data1", "data2" ,etc., but i want to be able to use the app.ActiveChannelsListBox.Items as the legend entries. I know i am able to change the legend names using the property app.UIAxes.Legend.String, but the problem is that if i have only 3 list box items selected i have no way of accessing only the selected variable names to assign as legend items.

legend(app.UIAxes)
if length(app.ActiveChannelsListBox.Value) == 1
    plot(app.UIAxes, app.TimeData, app.ActiveChannelsListBox.Value{1})
elseif length(app.ActiveChannelsListBox.Value) == 2
    plot(app.UIAxes, app.TimeData, app.ActiveChannelsListBox.Value{1})
    hold on
    plot(app.UIAxes, app.TimeData, app.ActiveChannelsListBox.Value{2})
    hold off
%elseif statements repeated to allow plotting using up to 16 list box selections
end

Answer 1

[Adam Danz]

Use the "DisplayName" property in your call to plot(). Also, move the call to legend() after your're done plotting.

But first, app.TimeData seems to be your X values. What are your Y values? The app.ActiveChannelsListBox values are all strings which I suppose you want as legend strings.

 plot(app.UIAxes, app.TimeData, y, 'DisplayName',app.ActiveChannelsListBox.Value) 
 legend(app.UIAxes)

[AdamG2013468]

Actually, my app.ActiveChannelsListBox.Value represents my Y-axis data (e.g. acceleration, type double). It is an 1 x n cell array, where n = the number of selected items. That is the problem, because i cannot find a way to access the selected ListBox items name as a string, which i could then use to define the legend item names using your method above.

[Adam Danz]

I thought the app.ActiveChannelsListBox value was the string selected here

What is "app.ActiveChannelsListBox" if it's not the handle to your listbox and why is it named as if it were a handle to a listbox?

To get the sting of your selection, you just need

app.ListBox.Value 

where ListBox is the handle to your listbox.

[Adam Danz]

If you're allowing for multiple selections and you want the Nth selected item to be the label for the Nth line object,

labs = app.ListBox.Value; 
plot(...,'DisplayName',labs{1})

[AdamG2013468]

app.ActiveChannelsListBox is the handle to my listbox. See the below for all the handle properties.

The above properties are for when three items are selected from the listbox, in this case they are channels 0, 1, and 2.

[Adam Danz]

I see what's happening. I didn't know you were using the ItemsData property which is usually empty. That screenshot of the property values is what I needed.

app.ListBox.Value usually contains the string(s) you just selected from the listbox. However, when you're using the ItemsData property, it contains those data instead.

Unfortunately there isn't a property that tells you which rows were selected. Usually you can match the string in app.ListBox.Value with the strings in app.ListBox.Items to find the row number. But that's more complicated when you have to match the ItemsData.

It's a really dumb issue with the list boxs.