Get label name of item in dropdown menu

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John F
John F on 8 Apr 2022
Commented: John F on 14 Apr 2022
I have 2 dropdown menus that allow the user to select which variables to plot on a figure. I would like to also update the labels of the plot according to the label name of the selected item. Is there a way to access the label name without passing an object to ItemsData (e.g. {["var1",1],["var2",2], ...})?
data = ones(1,length(table_cols)-1); % Dummy data
eng_perf = uitab(PlotTabGroup,'Title','Engine Perf.');
perf_plot = uiaxes(eng_perf,"Units","normalized","Position",[0 0.05 1 0.95]);
% table_cols contains the names of the items
xdrop = uidropdown(eng_perf,"Position",[10 5 100 20],'Items',table_cols(2:end),...
ydrop = uidropdown(eng_perf,"Position",[120 5 100 20],'Items',table_cols(2:end),...
xdrop.ValueChangedFcn = @(xdrop,event) update_perf_plot(xdrop,ydrop,perf_plot);
ydrop.ValueChangedFcn = @(ydrop,event) update_perf_plot(xdrop,ydrop,perf_plot);
function update_perf_plot(xdrop,ydrop,perf_plot)
perf_plot.XLabel.String = xdropSelectedName; % Replace this line
perf_plot.YLabel.String = xdropSelectedName; % Replace this line

Answers (1)

Geoff Hayes
Geoff Hayes on 12 Apr 2022
@John F - since you are passing the drop down objects into the callback, I think you could just do
function update_perf_plot(xdrop,ydrop,perf_plot)
perf_plot.XLabel.String = xdrop.Value;
perf_plot.YLabel.String = ydrop.Value;
% !! Not sure what the next line is supposed to do !!
% plot(perf_plot,xdrop.Value,ydrop.Value)
That would allow you to set the current selection from each drop down to the appropriate label. As mentioned in the above code, it isn't clear to me how these same two values (strings) are supposed to be used in your call to plot.
There may also be alternatives to passing the drop down objects into this callback. If you have nested your callback within the main code that creates the drop downs, then you can access them directly. For example,
function nestedFunctionExample
eng_perf = uifigure;
xdrop = uidropdown(eng_perf,"Position",[10 5 100 20],'Items',{'abc' 'def' 'ghi'},...
ydrop = uidropdown(eng_perf,"Position",[120 5 100 20],'Items',{'abcd' 'defd' 'ghid'},...
xdrop.ValueChangedFcn = @(xdrop,event) update_perf_plot;
ydrop.ValueChangedFcn = @(ydrop,event) update_perf_plot;
function update_perf_plot()
fprintf('xdrop=%s\n', xdrop.Value);
fprintf('ydrop=%s\n', ydrop.Value);
John F
John F on 14 Apr 2022
@Geoff Hayes This does work but since I need to update the data contained in the map, I would also have to pass the keys around in my app. So I will keep my solution as is. I appreciate the help though and I hope someone else finds it useful in the future!

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