User Interfaces in Excel and MATAB

Kipp MartinUniversity of Chicago

Booth School of Business

March 6, 2012

1

Files

Excel Files:

I vanillaConeGUI.xlsm

I hotFudgeGUI.xlsm

MATLAB Files:

I vanillaConeGUI.m

I vanillaConeGUI.fig

I simulationDemoGUI.m

I simulationDemoGUI.fig

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Outline

GUI BasicsMotivation

VBA GUIsGUI ToolsGenerating the CodeOther Issues

MATLAB GUIs

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GUI Basics

Building a GUI in MATLAB is very similar to building one VBA (orany other IDE for that matter).

Key Ideas:

I There is a user interface (or user form) that the user interactswith in order to generate the model data

I There are “tools” that are part of a tool box used to constructthe user interface

I These tools generate stubs or callback functions.

I When you “click” on things this generate eventscorresponding to the callback functions. The code in thesefunctions is executed.

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Motivation

Why a GUI?

I Make it easy for the user! The user may not know aboutoptimization, simulation, or even much about Excel orMATLAB.

I Accuracy. By controlling the input into the model we havemore accurate data entry. Example – entering the State in aWeb form.

I Speed. It is much faster for the user to cycle through theGUI inputs than figure things out from scratch.

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VBA GUI Basics

A blank VBA user form. To get a UserForm go into the VBAeditor and select Insert → UserForm.

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VBA GUI Basics

The VBA ToolBox. See the “hammer and wrench” icon to bring upthe tool box. It is also available under View in the VBA Toolbar.

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VBA GUI Basics

A VBA user form with tools. (Drag them over from the Toolbox)

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VBA GUI Basics

Here is what the user will see.

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VBA GUI Basics

Here is the VBA property explorer.

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GUI Tools

I Command Button (VBA) Push Button (MATLAB):clicking on this will cause a procedure or function to execute.

I TextBox (VBA) Edit Text (MATLAB): used to enterparameter values or show values to the user – used for bothinput and output.

I Label (VBA) Static Text (MATLAB): Used to “explain”the other tools to the user. These cannot be used to provideany information to the code.

I ScrollBar (VBA) Slider (MATLAB): Can select values in acontinum between a min and max value.

I Image (VBA) Axes (MATLAB): Display a graphic.

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GUI Tools

I ListBox (VBA) Pop-Up Menu (MATLAB): select from afinite set of options.

I CheckBox (VBA) Check Box (MATLAB): select an optionif desired.

I OptionButton (VBA) Radio Button (MATLAB): selectamong several options

I Frame (VBA) Panel (MATLAB) organize a related set oftools or options

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GUI ToolsEach of the GUI tools has a Properties Window (Inspector).Here is one for VBA. Click on the icon in the User Form to bring itup.

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GUI ToolsHere is one for MATLAB. Click on the icon in the User Form tobring it up.

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Generating the Code

KEY IDEA ONE:For each tool there is an empty stub or callback Sub or function.VBA

Private Sub CommandButton1_Click()

End Sub

MATLAB

% --- Executes on button press in pushbutton1.

function pushbutton1_Callback(hObject, eventdata, handles)

% hObject handle to pushbutton1

% eventdata reserved - to be defined in a

%future version of MATLAB

% handles structure with handles and

%user data (see GUIDATA)

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Generating the Code

KEY IDEA TWO: You fill in the stub or callback with your owncode! VBA code for clicking on the Generate Histogram button.

numTrials = num_trials_scrollBar.Value

numBins = ListBox1.Value

ReDim values(numTrials)

Dim i As Long

For i = 1 To numTrials

values(i) = RandNorm(0, 1)

Next i

Dim chartName As String, fname As String

Call CreateHistogram("Histogram", numBins, values)

fname = ThisWorkbook.Path & "\temp.gif"

Worksheets("Histogram").ChartObjects(1).Chart.Export _

Filename:=fname, FilterName:="GIF"

Image1.Picture = LoadPicture(fname)

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Generating the Code

KEY IDEA TWO: You fill in the stub or callback with your owncode! MATLAB code for clicking on the Generate Histogrambutton.

function gen_Histogram_Callback(hObject, ...

eventdata, handles)

hist (randn(1, handles.num_trials), ...

handles.number_bins);

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Generating the Code

KEY IDEA THREE: The code is executed when you “click” or“change” a tool. This generates an event or callback.

VBA ScrollBar: the following code is generated when you movethe scroll bar.

Private Sub num_trials_scrollBar_Change()

slider_value.Text = num_trials_scrollBar.Value

End Sub

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Generating the Code

KEY IDEA THREE: The code is executed when you “click” or“change” a tool. This generates an event or callback.

MATLAB Slider: The following code is generated when you movethe slider.

function num_trials_slider_Callback(hObject, ...

eventdata, handles)

slider_value = get(hObject,’Value’)

handles.num_trials = floor( slider_value)

slider_value_Callback(hObject, eventdata, handles);

guidata(hObject,handles)

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Generating the Code

KEY IDEA FOUR: You must get “data” from the tools.

Here is how to get the value of the VBA ScrollBar(num trials scrollBar Change is the name of the VBAprocedure called on the event)

num_trials_scrollBar.Value

Here is how to get the value of the MATLAB Slider(num trials slider Callback is the name of the MATLABfunction called on the event)

slider_value = get(hObject,’Value’)

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Generating the Code

KEY IDEA FOUR: A second example.

Here is how to get the value of the ListBox(histogram listbox Click is the name of the VBA procedurecalled on the event)

Private Sub histogram_listbox_Click()

End Sub

Note that we don’t need to set any values in the procedure.Anywhere else in the code we can get the value using the statement

numBins = histogram_listbox.Value

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Generating the Code

KEY IDEA FOUR: A second example. Life is more complicatedin MATLAB.

function histogram_popup_Callback(hObject, eventdata, ...

handles)

val = get(hObject,’Value’)

str = get(hObject, ’String’)

switch str{val};

case ’20’

handles.number_bins = 20;

case ’50’

handles.number_bins = 50;

case ’100’

handles.number_bins = 100;

case ’1000’

handles.number_bins = 1000 ;

end

guidata(hObject, handles);22

Generating the Code

KEY IDEA FOUR: A second example. Life is more complicatedin MATLAB.

To better understand the previous slide, here is MATLABgenerates for val and str.

val = 3

str = ’20’

’50’

’100’

’1000’

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Generating the Code

KEY IDEA FIVE: Transferring data between the functions orprocedures.

Life is much nicer with VBA. With VBA you can call the “value”of a procedure from anywhere in the User Form code. Forexample, in the Generate Histogram code we have:

numTrials = num_trials_scrollBar.Value

numBins = histogram_listbox.Value

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Generating the Code

KEY IDEA FIVE: Transferring data between the functions orprocedures.In MATLAB we put the data in a handler called handles. In thisexample we need the number of bins (numBins) and number of

trials (numTrials) to build the histogram.

Get the number of bins.

handles.number_bins = 1000 ;

Get the number of trials.

slider_value = get(hObject,’Value’)

handles.num_trials = floor( slider_value)

Pass the information to the other functions.

guidata(hObject,handles)

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Generating the Code

KEY IDEA FIVE: Transferring data between the functions orprocedures.In MATLAB we put the data in a handler called handles. In thisexample we need the number of bins (numBins) and number of

trials (numTrials) to build the histogram.

After putting the data in the handles we can use it

anywhere else. For example in the Generate Histogramfunction gen Histogram Callback we have

hist (randn(1, handles.num_trials), ...

handles.number_bins);

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Initialization

In VBA there is an initialization routine that calledUserForm Click() that gets called before the user sees the form.You can initialize data here. See my code where I initialize thevalues for the possible number of bins.

In VBA it is common to call the UserForm Click() from amain() procedure. This is done as simulationGUI.Show, wheresimulationGUI is the name of my User Form.

In MATLAB there is an initialization routine that calledsimulationDemoGUI OpeningFcn that gets called before the usersees the form. You can initialize data here. See my code where Iparameter values for the histogram.

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Start-up Worksheet

In VBA you can control the first worksheet the user sees and whichworksheets are visible. Here is my code.

Private Sub Workbook_Open()

Dim ws As Object

Worksheets("Begin").Activate

For Each ws In ActiveWorkbook.Sheets

If ws.Name <> "Begin" Then ws.Visible = False

Next

End Sub

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MATLAB GUI Basics

A blank MATLAB user form. The tool box is on the left. SelectFile and then New and then Figure to get this. There is also aToolbar icon.

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MATLAB GUI BasicsA MATLAB user form with tools. (Drag them over)

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MATLAB GUI Basics

Here is what the user will see.

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