Matlab GUI - A simple but powerful command: questdlg

Matlab - A Simple but Powerful Command: questdlg

14 Mar 2008 Quan Quach 15 comments 2,840 views

Introduction

Sometimes, the simplest of things can prove to be quite useful. I want to promote the questdlg command within Matlab because I think its a very useful command that people either 1) overlook, or 2) does not know that it even exists! With this command, you can create a pop-up window that will ask you a question, and will allow you to choose one of the options. For instance, if we use the following code, we can create a window that queries the user for their favorite color. Go ahead and copy and paste the following code into the Matlab command prompt.

%this example comes directly from the Matlab help
ButtonName = questdlg('What is your favorite color?', ...
                         'Color Question', ...
                         'Red', 'Green', 'Blue', 'Green');

Favorite Color

Once you click on any of the buttons, it will return the appropriate argument into the variable ButtonName. Read the rest of this tutorial for some practical examples on how to use the questdlg command.

Close GUI Confirmation

I already covered a very good use of questdlg in a previous tutorial: Close confirmation for GUI. Using the questdlg command, you can confirm if the user really wants to exit the GUI.

Save Data Confirmation

Along the same lines, you can program a GUI to ask for confirmation when the user is performing a particular action. For instance, maybe the user did not save their data and tries to perform another operation that would wipe out the current data.

ButtonName = questdlg('Do you want to save current data first?', ...
                         'Save Data', ...
                         'Yes', 'No', 'Yes');
 
%perform the following operation depending on the option chosen
switch ButtonName,
     case 'Yes',
      %add code here for saving data
     case 'No',
      %add code here when data is not saved
end % switch

Save Data

Warn User of Excessive Processing Time

Perhaps the user is trying to process a data file that is very large and will take a long time. We can warn the user with the following use of questdlg, allowing them to either continuing with the data processing, or to abort it.

ButtonName = questdlg('Processing this file may take up to 30 minutes.', ...
                         'Process Data', ...
                         'Continue', 'Abort', 'Continue');
 
%perform the following operation depending on the option chosen
switch ButtonName,
     case 'Continue',
      %continue the current operation
     case 'Abort',
      %abort the current operation
end % switch

Large Data Set

Versatile and Flexible

The questdlg command is very flexible and versatile and can be used in a variety of situations. There are many situations wherein this command is useful which I did not discuss in this tutorial. After reading this tutorial, I hope you are able to apply this knowledge and use it to create better interfaces!

15 Responses to “Matlab - A Simple but Powerful Command: questdlg”

on 15 Mar 2008 at 7:47 am 1Natural Blogarithms » Matlab GUI - A simple but powerful command: questdlg

[...] about questdlg, a very cool little command in Matlab that I plan on making great use of. HT: blinkdagger . . . if we use the following code, we can create a window that queries the user for their [...]
on 15 Mar 2008 at 10:36 am 2Mike K

I’m currently using your tutorials to complete the GUI for a thesis project. I have already learned a lot just by browsing your site, so much so that you’ll be cited in my bibliography.

Thanks for all the help,
-Mike
on 15 Mar 2008 at 11:28 am 3Quan Quach

Wow, thanks Mike!! Hope your thesis turns out well!
on 27 Mar 2008 at 10:53 am 4Sharina

Dear Quan,

This is absolutely amazing.
Thanks a lot for this very helpful post.

But i need ur help urgently in the ‘ResizeFcn’ issue i pointed out in an earlier comment.
Please do help me with the resizing of matlab GUI window.

Expecting a response at the earliest.

Regards,
Sharina
on 27 Mar 2008 at 11:37 am 5Quan Quach

Hi Sharina,

Doug Hull over at mathworks covered that issue in this post:

http://blogs.mathworks.com/pick/2008/02/15/gui-layout-part-1/

Quan
on 28 Apr 2008 at 8:19 am 6Peter

Hi Quan,

Thanks for all the great tutorials.

Would there be a way to use the questdlg, and also record the person’s response, as well as the TIME it takes for him/her to choose that response using MATLAB?

Also, would it be possible to make it so that we can provide feedback on the person’s response. For instance, if they click Button A, they receive an ‘Incorrect’ message and try again, but if they click Button B they receive a correct message, and then another pop-up window will appear and the process starts over again??
on 13 Aug 2008 at 2:29 am 7Eghosa John

am having problem trying to get time responses.
Response of temperature and gas generator speed to a unit step change in gas generator speed demand
on 04 Sep 2008 at 5:51 pm 8icxhukn lukgiqj

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on 07 Dec 2008 at 5:39 pm 9sanyo hifi

Good site. Thank you.
on 12 Jun 2009 at 5:39 am 10Question as GUI in Matlab – OpenSource-Ideas

[...] cool. check this blog or the matlab help for more info. This entry was posted on Friday, May 16th, 2008 at 17:15 and is [...]
on 05 Aug 2009 at 7:03 pm 11Astromoof

Hi guys,

Great site, sooo useful!!

Im wondering if a questdlg can have more than 3 buttons.

I need to have 4 and matlab is telling me i have too many input arguments.

Thanks
on 06 Aug 2009 at 12:43 pm 12Zane Montgomery

Astromoof,

Unfortunately, from what I’ve seen, 3 is the maximum number of options. I did find a possible alternative though… but it’s not as pretty.

Make a string out of your options Then have the user choose from the list.
```
str={'Red','Blue','Green','Orange','Black'};
 
[s,v] = listdlg('PromptString','Select a file:','SelectionMode','single','ListString',str);
 
pick=str{s}
```
It is a little trickier if you want to select a couple options, but that doesn’t sound like you need to do that if you were just gonna use questdlg anyways.

Requires one extra click more than questdlg would (select, then ‘ok’) but it should do the job.

Good luck!
-Zane
on 06 Aug 2009 at 2:57 pm 13Astromoof

Hi Zane,

It’s excellent! Revolutionary for my code, thank you soooo much.
Im trying to idiot proof my code by getting users to pick things instead of type inputs (without me having to write a full-on GUI)

Only problem now is that i can implement this listdlg in so many places now, got alot of work ahead

Thank you so much, i love your site

on 11 Aug 2009 at 7:11 pm 14Astromoof

Hey Guys, Im going nuts.

Im trying to write a function that pulls the names of materials in from a xls file. The way ive written it is so that if someone changes one of the materials in the xls file, the listdlg will have that name in it too.

my problem is that is seems all the material names have to be the same lenght or something.

Can i send you my xls file to run my come below to see if you get the “matrix dimensions must agree” error.

Thanks from Astromoof

the xls is basically (the names start in row 4)
(in column 2) (in column 3) (in column 4) (in column 5)
MetalA 1.0 2.0 3.0
MetalB 2.0 6.0 5.0
MetalC (3 values for each material is filled in)
MetalD
Carbon_1
Cardon_2
Plactic_1
Plactic_2
Additional1
Additional2
Additional3
Additional4
Additional5
Additional6
Additional7
Additional8
Additional9
Additional10
Additional11
Additional12

 
% Function For Selecting Materials
%
% Function Name: MAT   
% INPUTS:        object
% OUTPUTS:       objectmat, z
 
%function [objectmat, z] = MAT (object)
 
[numericalData, textData, rawData] = xlsread('MATDB.xls','Materials');
MATDBB = (rawData(:,2));
 
% List of Materials
MATDB01  = char(MATDBB( 4,1))   ;
MATDB02  = char(MATDBB( 5,1))   ;
MATDB03  = char(MATDBB( 6,1))   ;
MATDB04  = char(MATDBB( 7,1))   ;
MATDB05  = char(MATDBB( 8,1))   ;
MATDB06  = char(MATDBB( 9,1))   ;
MATDB07  = char(MATDBB(10,1))   ;
MATDB08  = char(MATDBB(11,1))   ;
MATDB09  = char(MATDBB(12,1))   ;
MATDB10  = char(MATDBB(13,1))   ;
MATDB11  = char(MATDBB(14,1))   ;
MATDB12  = char(MATDBB(15,1))   ;
MATDB13  = char(MATDBB(16,1))   ;
MATDB14  = char(MATDBB(17,1))   ;
MATDB15  = char(MATDBB(18,1))   ;
MATDB16  = char(MATDBB(19,1))   ;
MATDB17  = char(MATDBB(20,1))   ;
MATDB18  = char(MATDBB(21,1))   ;
MATDB19  = char(MATDBB(22,1))   ;
MATDB20  = char(MATDBB(23,1))   ; 
 
% List Box to Select Material
str1 = { MATDB01,...
         MATDB02,...
         MATDB03,...
         MATDB04,...
         MATDB05,...
         MATDB06,...
         MATDB07,...
         MATDB08,...
         MATDB09,...
         MATDB10,...
         MATDB11,...
         MATDB12,...
         MATDB13,...
         MATDB14,...
         MATDB15,...
         MATDB16,...
         MATDB17,...
         MATDB18,...
         MATDB19,...
         MATDB20 };
 
[s1] = listdlg('PromptString','Select Case Material:','SelectionMode','single','ListString',str1);
 
s1 = str1{s1}
 
if s1 == MATDB01
z=1    
end
if s1 == MATDB02
z=2
end
if s1 == MATDB03
z=3
end
if s1 == MATDB04
z=4
end
if s1 == MATDB05
z=5
end
if s1 == MATDB06
z=6
end
if s1 == MATDB07
z=7
end
if s1 == MATDB08
z=8
end
if s1 == MATDB09
z=9
end
if s1 == MATDB10
z=10
end
if s1 == MATDB11
z=11
end
if s1 == MATDB12
z=12
end
if s1 == MATDB13
z=13
end
if s1 == MATDB14
z=14
end
if s1 == MATDB15
z=15
end
if s1 == MATDB16
z=16
end
if s1 == MATDB17
z=17
end
if s1 == MATDB18
z=18
end
if s1 == MATDB19
z=19
end
if s1 == MATDB20
z=20
end

on 11 Aug 2009 at 7:49 pm 15Astromoof

Hi Guys,

Im such an idiot, i figured out a way to do it.

I appreciate that you would have helped me (if i didnt ask stupid questions)

THanks

Include MATLAB code in your comment by doing the following:

<pre lang="MATLAB">

%insert code here

</pre>

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