MATLAB AppDesigner ListBox - matlab

Question

Good afternoon!
I'm currently trying to build an app with MATLAB using App Designer. The goal is to be able to plot data using multiple GPX files, which I have successfully done. I'm curious as to how I should go about populating my Listbox.
Is there a way for Listbox to get populated with filenames depending on the folder you select?

Answer 1

You can use dir to list folder's content, convert names list to cell array, and populate the ListBox Items with the cell array.
Assume you have a Button with ButtonButtonPushed callback, and you wish to let the user select a folder, and then populate the list box with all *.gpx files.
You can do it as follows:
% Button button pushed function
function ButtonButtonPushed(app)
selpath = uigetdir(); %Open dialog box for selecting folder.
gpx_files = dir(fullfile(selpath, '*.gpx')); %Dir all *.gpx in selected folder.
%Populate listbox with file names:
app.ListBox.Items = {gpx_files(:).name};
end
The statement app.ListBox.Items = {gpx_files(:).name}; populates the ListBox.
gpx_files(:).name is a list of file names.
{gpx_files(:).name} creates a cell array out of the list.
app.ListBox.Items = {gpx_files(:).name}; Sets the Items property of the ListBox with the created cell array.
Getting the full path of the selected file:
Keep the selected folder:
Add a private property named selpath (use the red P+ in the designer [code view] to add new property, and edit the name of the property):
properties (Access = private)
selpath % Store selected path
end
Store the selected path in selpath property when button is pressed:
% Button pushed function: Button
function ButtonButtonPushed(app, event)
app.selpath = uigetdir(); %Open dialog box for selecting folder.
gpx_files = dir(fullfile(app.selpath, '*.gpx')); %Dir all *.gpx in selected folder.
%Populate listbox with file names:
app.ListBox.Items = {gpx_files(:).name};
end
Now selected path is stored in app.selpath.
Add "ListBoxChangeValue" Callback (right click the list box in design view).
Edit the code of ListBoxValueChanged function:
The value returned value = app.ListBox.Value; is the name of the selected file
(you don't need to use strcmpi).
Use fullfile function to concatenate the path with the file name.
% Value changed function: ListBox
function ListBoxValueChanged(app, event)
value = app.ListBox.Value;
selected_file = fullfile(app.selpath, value); %Get the full path of selected file.
disp(selected_file) %Change the code to load selected_file
end
The above code displays selected_file string in the Command Window.
Replace the disp(selected_file) with you own code (loading and plotting the gpx file).
Here is the complete code of App1 (most of the code was generated automatically):
classdef App1 < matlab.apps.AppBase
% Properties that correspond to app components
properties (Access = public)
UIFigure matlab.ui.Figure
Button matlab.ui.control.Button
LabelListBox matlab.ui.control.Label
ListBox matlab.ui.control.ListBox
end
properties (Access = private)
selpath % Store selected path
end
% Callbacks that handle component events
methods (Access = private)
% Code that executes after component creation
function startupFcn(app)
end
% Button pushed function: Button
function ButtonButtonPushed(app, event)
app.selpath = uigetdir(); %Open dialog box for selecting folder.
gpx_files = dir(fullfile(app.selpath, '*.gpx')); %Dir all *.gpx in selected folder.
%Populate listbox with file names:
app.ListBox.Items = {gpx_files(:).name};
end
% Value changed function: ListBox
function ListBoxValueChanged(app, event)
value = app.ListBox.Value;
selected_file = fullfile(app.selpath, value); %Get the full path of selected file.
disp(selected_file) %Change the code to load selected_file
end
end
% Component initialization
methods (Access = private)
% Create UIFigure and components
function createComponents(app)
% Create UIFigure and hide until all components are created
app.UIFigure = uifigure('Visible', 'off');
app.UIFigure.Position = [101 101 640 480];
app.UIFigure.Name = 'UI Figure';
% Create Button
app.Button = uibutton(app.UIFigure, 'push');
app.Button.ButtonPushedFcn = createCallbackFcn(app, #ButtonButtonPushed, true);
app.Button.Position = [43 380 114 49];
app.Button.Text = 'Select Folder';
% Create LabelListBox
app.LabelListBox = uilabel(app.UIFigure);
app.LabelListBox.HorizontalAlignment = 'right';
app.LabelListBox.VerticalAlignment = 'top';
app.LabelListBox.Position = [300 412 44 15];
app.LabelListBox.Text = 'List Box';
% Create ListBox
app.ListBox = uilistbox(app.UIFigure);
app.ListBox.ValueChangedFcn = createCallbackFcn(app, #ListBoxValueChanged, true);
app.ListBox.Position = [359 355 100 74];
% Show the figure after all components are created
app.UIFigure.Visible = 'on';
end
end
% App creation and deletion
methods (Access = public)
% Construct app
function app = App1
% Create UIFigure and components
createComponents(app)
% Register the app with App Designer
registerApp(app, app.UIFigure)
% Execute the startup function
runStartupFcn(app, #startupFcn)
if nargout == 0
clear app
end
end
% Code that executes before app deletion
function delete(app)
% Delete UIFigure when app is deleted
delete(app.UIFigure)
end
end
end