MATLAB: How to get index of selected item in listbox of appdesginer

duplicate valuesduplicatesindex of selected item in listbox of appdesginerlistbox

Hi:

I want to get the index of selected item in listbox of appdesigner.

I found a solution here: https://www.mathworks.com/matlabcentral/answers/376091-index-of-the-items-in-a-listbox

The weakness of the solution provided here using 'ismember' function is that, if I have two items that are totally the same, the returned index is not unique. so, is there any other solutions?

Thanks!

Best Answer

Continuing from comments under the question.

There is unfortunately no property of a listbox that returns the index of the selected item. The only way to get the index is by finding the selection within a list of options by using strcmp() or ismember() etc. If your list of options has duplicates and one of the duplicates was selected, there is no way to match which of the duplicates was selected.

One potential workaround in app designer is to assign unique values to the ItemsData property. When the ItemsData property is set, the Value property of a listbox returns the ItemsData selection rather than the Items selection.

Example:

fig = uifigure();
lbx = uilistbox(fig,'Items',{'Apples','Apples','Pears','Bananas'}, ...
    'ItemsData',{'Apples1','Apples2','Pears1','Bananas1'});

Now when the 2nd "Apples" is selected,

lbx.Value
ans =
    'Apples2'

Related Solutions

MATLAB: Select all items of a list box within app designer

For everyone who is interested:

I opened a support ticket and learned, that the development team is aware of this performance issue with large multi-select ListBox.

Numeric values in ItemsData (instead of Items), should be slightly faster (~20% faster) than using Items if this is a high frequency workflow.

app = struct;
app.ListBox = uilistbox('Items', "Items" + (1:1000));
app.ListBox.Multiselect = 'on';
app.ListBox.ItemsData = 1:1000;
% Start timer
tic
% read all items from the list box
ItemsData = app.ListBox.ItemsData; % USE ItemsData instead of Items
% stop the timer and write the time to a variable
ReadItemsTime = toc;
% start a second timer
tic
% Select all Itmes, by passing the cell array to the Value
% variable
app.ListBox.Value = ItemsData;
% stop the second timer
WriteValueTime = toc;
% display the times
disp(['Read items from the list box: ' num2str(ReadItemsTime) ' s'])
disp(['Write items to the Value variable: ' num2str(WriteValueTime) 's'])

MATLAB: Matlab App Designer ListBox.Value changes when ItemsData is an array

I think what you're looking for is,

[~,index] = ismember(app.ListBox.Value, app.ListBox.ItemsData); % Note: ItemsData
% This returns a character vector; it won't work with >1 selection
value = app.ListBox.Items{index};
% This returns a cell containing char-vectors
value = app.ListBox.Items(index);

Best Answer

Related Solutions

MATLAB: Select all items of a list box within app designer

MATLAB: Matlab App Designer ListBox.Value changes when ItemsData is an array

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