Matlab GUI Tutorial - How to Stop a Long Running Function

Matlab GUI Tutorial - How to Stop a Long Running Function without using “control + c”

07 Dec 2007 Quan Quach 21 comments 14,389 views

Introduction

This tutorial will show you how to stop a function that is running from within a GUI. Most of the time, when we want to stop a function from running, we simple use the almighty "control + c" combination. But all this really does is kill the entire process thread, which may sometimes be undesirable. This tutorial will show you how to stop a function with the press of a button without killing the GUI. This feature is most helpful when you have long running “for” or “while” loops.

This tutorial is written for those with some experience creating a Matlab GUI. If you’re new to creating GUIs in Matlab, you should visit this tutorial first. Basic knowledge of Matlab and an understanding on how data is shared among callbacks is highly recommended. Matlab version 2007a is used in writing this tutorial. Both earlier versions and new versions should be compatible as well (as long as it isan’t too outdated). Let’s get started!

The Example Files and Code

First, download the sample GUI here. Unzip the files and place them wherever you please.
Now, type guide at the command prompt.
Choose to open the sample GUI by clicking on “Open Existing GUI”. Click on “Browse” to locate where you saved the GUI files.
Here is what the GUI should look like when you open it:
Click on the icon on the GUI figure to bring up the accompanying .m file.

Now, add the following code to start_pushbutton_Callback. In order for this interrupt function to work properly, we must use the UserData property. All GUI components, including menus, and the figure have a UserData property. You can assign any valid MATLAB value to the UserData property. Thus, in this case, we are using the UserData property to store the flag variable value.

%initialize the flag variable
set(handles.start_pushbutton,'UserData',1); 
 
%while the flag variable is one, the loop continues
while (get(handles.start_pushbutton,'UserData') ==1)
    %increments the counter
    temp = str2num(get(handles.counter_text,'String'));
    temp = temp + 1;
    set(handles.counter_text,'String',num2str(temp));
 
    %"flushes the event queue" and updates the figure window
    %since Matlab is a single thread process, this command is requierd
    drawnow
end
 
guidata(hObject, handles);

Now, add the following code to stop_button_Callback.

%toggle the flag variable so that the other process will stop
set(handles.start_pushbutton,'UserData',0);
guidata(hObject, handles);

Now, save your .m file and run the GUI. You should see the following GUI appear
Press the start button to activate the GUI. You should see the text box displaying a number that is rapidly increasing. Whenever you want the process to stop, simply press the stop button.
You can resume the GUI by pressing the start button again.

Download Source Files

Click here to download the source files.

This is the end of the tutorial.

21 Responses to “Matlab GUI Tutorial - How to Stop a Long Running Function without using “control + c””

on 14 Jan 2008 at 6:22 am 1a student

Thanks a lot! It was very helpful.
on 30 Jan 2008 at 10:55 am 2naor

That can be a very useful technique. Can you give us your opinion on what would be a good way to make a generic pause/play gui that works with an external calculation?

Thanks,
-naor
on 06 Mar 2008 at 6:34 pm 3mei

I have a audio signal which sometimes taking too long to load, so i need to set a stop button just in case the user wants to stop running the program. However, if i use the method as shown above, the sound will nonstop looping in the while loop n having multiple repeat sound until i click the button. is there any way that the sound will oni produce once and also to have a stop button to stop the long prog to run (like how ctrl c function )??
on 14 Aug 2008 at 2:35 pm 4Kinnison

hehe this is a clever little trick. thanks, this is going to be very helpfull as I will put it to use immediately.
on 05 Sep 2008 at 7:17 am 5AntonN

Thank you extra very much! I was simply searching for something like ‘drawnow’.
on 11 Sep 2008 at 6:30 am 6JohnC

First I’d like to say thanks, this is very useful, as is your entire site. Keep up the good work!

I have used your above approach to put “play”/”pause”/”reset” buttons on a GUI that continually updates graphical plots as data changes over time.

However, I find that unless I put a fairly large pause (pause(0.2), say) statement in the loop, the GUI does not respond to button presses - and even with the pause its necessary to repeatedly press.

I am new to Matlab. In Java I would have the button press wait on the event queue, but Matlab is single-threaded, right? So, is there a more elegant way, or am I stuck with pause?
on 19 Sep 2008 at 1:29 pm 7chalina

Thanks a lot!!!
on 15 Oct 2008 at 2:34 pm 8Luis

This was actually helpful not as a start/stop (I use uiwait & uiresume for that), but more so to dynamically update a ‘time’ counter as the loop moves and make it visible to the user. Thanks!
on 15 Oct 2008 at 8:49 pm 9Quan Quach

Glad it was helpful!
on 28 Oct 2008 at 11:16 am 10Herman

Thank’s a lot, this seems a simply example but this gonna rise the development of the newer user of guide & gui. This gonna help me with a PaP motor.
on 10 Dec 2008 at 3:39 am 11_yak vs. world » Blog Archive » Matlab Tips

[...] Read input without wait from the keyboard in Matlabs main thread, here and see the related tutorial. [...]
on 02 May 2009 at 11:33 am 12Pawel

Hi!
It’s very helpful and easy solution!
Thanks
on 21 May 2009 at 1:59 am 13Hani

Thanks a lot for this site
on 25 May 2009 at 9:22 am 14TheBosss

A saver website :D, easy to follow and results right away … Thanks and keep it up
on 27 Aug 2009 at 9:57 pm 15student

all your tutorials have been so helpful.
easy to understand and very informative.
good luck in all your endeavors.
thank you very much!
on 13 Oct 2009 at 3:48 pm 16xuebo

thanks. it’s really helpful.
I’m using it in a similar application where I need to stop a video from continuous playing.
on 19 Nov 2009 at 5:20 am 17Marc

Thank you very much!

This trick helped me a lot!

on 01 Dec 2009 at 5:56 am 18kuldeep

 
function varargout = sourab2(varargin)
% SOURAB2 M-file for sourab2.fig
%      SOURAB2, by itself, creates a new SOURAB2 or raises the existing
%      singleton*.
%
%      H = SOURAB2 returns the handle to a new SOURAB2 or the handle to
%      the existing singleton*.
%
%      SOURAB2('CALLBACK',hObject,eventData,handles,...) calls the local
%      function named CALLBACK in SOURAB2.M with the given input arguments.
%
%      SOURAB2('Property','Value',...) creates a new SOURAB2 or raises the
%      existing singleton*.  Starting from the left, property value pairs are
%      applied to the GUI before sourab2_OpeningFunction gets called.  An
%      unrecognized property name or invalid value makes property application
%      stop.  All inputs are passed to sourab2_OpeningFcn via varargin.
%
%      *See GUI Options on GUIDE's Tools menu.  Choose "GUI allows only one
%      instance to run (singleton)".
%
% See also: GUIDE, GUIDATA, GUIHANDLES
 
% Copyright 2002-2003 The MathWorks, Inc.
 
% Edit the above text to modify the response to help sourab2
 
% Last Modified by GUIDE v2.5 11-Nov-2009 16:03:52
 
% Begin initialization code - DO NOT EDIT
gui_Singleton = 1;
gui_State = struct('gui_Name',       mfilename, ...
                   'gui_Singleton',  gui_Singleton, ...
                   'gui_OpeningFcn', @sourab2_OpeningFcn, ...
                   'gui_OutputFcn',  @sourab2_OutputFcn, ...
                   'gui_LayoutFcn',  [] , ...
                   'gui_Callback',   []);
if nargin &amp;&amp; ischar(varargin{1})
    gui_State.gui_Callback = str2func(varargin{1});
end
 
if nargout
    [varargout{1:nargout}] = gui_mainfcn(gui_State, varargin{:});
else
    gui_mainfcn(gui_State, varargin{:});
end
% End initialization code - DO NOT EDIT
 
 
% --- Executes just before sourab2 is made visible.
function sourab2_OpeningFcn(hObject, eventdata, handles, varargin)
% This function has no output args, see OutputFcn.
% hObject    handle to figure
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
% varargin   command line arguments to sourab2 (see VARARGIN)
 
 
%picture code
%load the background image into Matlab
%if image is not in the same directory as the GUI files, you must use the 
%full path name of the iamge file
backgroundImage = importdata('code-breakers-1.jpg');
%select the axes
axes(handles.axes1);
%place image onto the axes
image(backgroundImage);
%remove the axis tick marks
axis off
%confirimaation of clse GUI........
set(handles.figure1,'CloseRequestFcn',@closeGUI);
 
 
% Choose default command line output for sourab2
handles.output = hObject;
 
% Update handles structure
guidata(hObject, handles);
 
% UIWAIT makes sourab2 wait for user response (see UIRESUME)
% uiwait(handles.figure1);
 
 
% --- Outputs from this function are returned to the command line.
function varargout = sourab2_OutputFcn(hObject, eventdata, handles) 
% varargout  cell array for returning output args (see VARARGOUT);
% hObject    handle to figure
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
 
% Get default command line output from handles structure
varargout{1} = handles.output;
 
 
% --- Executes on button press in pushbutton1.
function pushbutton1_Callback(hObject, eventdata, handles)
% hObject    handle to pushbutton1 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
global txt
global pace
 
tts(txt,pace)
 
% --- Executes on button press in pushbutton2.
function pushbutton2_Callback(hObject, eventdata, handles)
% hObject    handle to pushbutton2 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
 
set(handles.edit1,'String','Enter your text here');
 
function edit1_Callback(hObject, eventdata, handles)
% hObject    handle to edit1 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
 
% Hints: get(hObject,'String') returns contents of edit1 as text
%        str2double(get(hObject,'String')) returns contents of edit1 as a double
 
 
% code here for msg box
 
 
 
 
 
global txt
 
 txt =  get(hObject,'String')
% --- Executes during object creation, after setting all properties.
function edit1_CreateFcn(hObject, eventdata, handles)
% hObject    handle to edit1 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    empty - handles not created until after all CreateFcns called
 
% Hint: edit controls usually have a white background on Windows.
%       See ISPC and COMPUTER.
if ispc
    set(hObject,'BackgroundColor','white');
else
    set(hObject,'BackgroundColor',get(0,'defaultUicontrolBackgroundColor'));
end
 
 
 
 
% --- Executes on selection change in popupmenu1.
function popupmenu1_Callback(hObject, eventdata, handles)
% hObject    handle to popupmenu1 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
 
% Hints: contents = get(hObject,'String') returns popupmenu1 contents as cell array
%        contents{get(hObject,'Value')} returns selected item from popupmenu1
global pace
pace= get(hObject,'Value')-12;
% --- Executes during object creation, after setting all properties.
function popupmenu1_CreateFcn(hObject, eventdata, handles)
% hObject    handle to popupmenu1 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    empty - handles not created until after all CreateFcns called
 
% Hint: popupmenu controls usually have a white background on Windows.
%       See ISPC and COMPUTER.
if ispc
    set(hObject,'BackgroundColor','white');
else
    set(hObject,'BackgroundColor',get(0,'defaultUicontrolBackgroundColor'));
end
 
 
 
 
 
%close confrimation....
function closeGUI(src,evnt)
%src is the handle of the object generating the callback (the source of the event)
%evnt is the The event data structure (can be empty for some callbacks)
selection = questdlg('Do you want to close the GUI?',...
                     'Close Request Function',...
                     'Yes','No','Yes');
switch selection,
   case 'Yes',
    delete(gcf)
   case 'No'
     return
end
 
....this is my text to speech converter project  so i want to create a stop button ...which stop the speaking text ...any time

on 18 Mar 2010 at 4:13 am 19nagi

thanks alot for this website,t’s very helpful
on 30 Mar 2010 at 12:23 am 20neojw

Hi sir. i have a problem with my stop button in my GUI program. the program codes are listed down below.When pushbutton1 is pressed, it runs the device and plots the waveform. But where do i place the codes for the stop button and how? I have tried putting while and if, setting the user data to 1, but it failed.

% — Executes on button press in pushbutton1.
function pushbutton1_Callback(hObject, eventdata, handles)
% hObject handle to pushbutton1 (see GCBO)
% eventdata reserved - to be defined in a future version of MATLAB
% handles structure with handles and user data (see GUIDATA)
set(handles.pushbutton1,’UserData’,1);

switch get(handles.popupmenu1,’Value’)

case 1

serobj = serial(’COM12′) ;
serobj.Baudrate = 19200;
set(serobj, ‘Parity’, ‘none’) ;
set(serobj, ‘Databits’, ;
set(serobj, ‘StopBits’, 1) ;
set(serobj, ‘Terminator’,'CR’);
set(serobj,’Readasyncmode’,'continuous’);
set(serobj,’InputBufferSize’, 480012)
set(serobj, ‘OutputBufferSize’,480012) ;
set(serobj, ‘Timeout’,1 ) ;
disp(’Connection to Syringe Pump through RS232 interface established’);
get(serobj) ;
fopen(serobj) ;

fprintf(serobj,’rat MH’);%set the infusion rate unit
fprintf(serobj,’VOL ML’);%set the volume unit
fprintf(serobj,’DIA 10.25′); %settings of the pump
%fprintf(serobj,’rat 1′);%default infusion rate of the pump to 1ML/H for machine calibration
%fprintf(serobj,’run’);%run the syringe pump

PI1;% the first PI controller is set to be the default controller
m=0;

%Loop for the controller selection, determine the Ki and Kp
for m=1:3

Condition;
Infusion_input;%calculate out the infusion rate.

fprintf(serobj,’rat %s\r’, num2str(u1,’%.2f’));%convert the infusion rate u1 to string, the /r is for the setting CR (Carriage Return)

%fprintf(serobj,’rat’); %send the specific parameter you want to get from the machine.
%out=fscanf(serobj)%Scan the machine port and get the value of the specific parameter.

for j=1:n2

Differential;
pause(1); % the pause time inbetween each calculation.

if ((t1>=90)&&(t1<=180)) %take samples of the MAP trajectory during 90s to 180s.

N=average_slop(t3,y);% calculate the average slop of the samples to compare with a predefined range to detemine which controller should be selected.

if(Ki==-0.0005)&&(Kp==-0.026)
compare;
break;
elseif(Ki==-0.0018)&&(Kp==-0.0500)
compare2;
break;
else
compare3;
break;

end

end
end
break;
end

%use the selected controller Ki,Kp values to recalculate the infusion rate.
fprintf(serobj,’run’);
Condition;
for j=1:n2
Infusion_input;%take the calculated infusion rate u1 value.
axes(handles.axes1)
axis([0 100 90 180]);
xlabel(’time(min)’);
ylabel(’MAP(mmHg)’);
y=y0+y(1);
plot(j,y,’-.r’);
hold on;%hold the point.
axes(handles.axes2)%plot the Infusion rate vs Time
axis([0 100 0 10]);
xlabel(’time(min)’);
ylabel(’SNP Infusion Rate(mmHg/hr)’);
plot(j,u1,’-');
hold on;%hold the point.
Differential;
fprintf(serobj,’rat %s\r’, num2str(u1,’%.2f’)); %send the infusion rate to the pump if the last controller is chosen.
fprintf(serobj,’rat’);
out=fscanf(serobj)
pause(1);
end

fprintf(serobj,’stp’)
delete(serobj);

on 30 Mar 2010 at 11:54 pm 21neojw

Hi sir. i have a problem with my stop button in my GUI program. the program codes are listed down below.When pushbutton1 is pressed, it runs the device and plots the waveform. But where do i place the codes for the stop button and how? I have tried putting while and if, setting the user data to 1, but it failed.

% — Executes on button press in pushbutton1.
function pushbutton1_Callback(hObject, eventdata, handles)
% hObject handle to pushbutton1 (see GCBO)
% eventdata reserved - to be defined in a future version of MATLAB
% handles structure with handles and user data (see GUIDATA)
set(handles.pushbutton1,’UserData’,1);
switch get(handles.popupmenu1,’Value’) 
case 1
serobj = serial(’COM12′) ;
serobj.Baudrate = 19200;
set(serobj, ‘Parity’, ‘none’) ;
set(serobj, ‘Databits’,  ;
set(serobj, ‘StopBits’, 1) ;
set(serobj, ‘Terminator’,'CR’);
set(serobj,’Readasyncmode’,'continuous’);
set(serobj,’InputBufferSize’, 480012)
set(serobj, ‘OutputBufferSize’,480012) ;
set(serobj, ‘Timeout’,1 ) ;
disp(’Connection to Syringe Pump through RS232 interface established’);
get(serobj) ;
fopen(serobj) ;
fprintf(serobj,’rat MH’);%set the infusion rate unit
fprintf(serobj,’VOL ML’);%set the volume unit
fprintf(serobj,’DIA 10.25′); %settings of the pump
%fprintf(serobj,’rat 1′);%default infusion rate of the pump to 1ML/H for machine calibration
%fprintf(serobj,’run’);%run the syringe pump
PI1;% the first PI controller is set to be the default controller
m=0;
%Loop for the controller selection, determine the Ki and Kp
for m=1:3
Condition;
Infusion_input;%calculate out the infusion rate.
fprintf(serobj,’rat %s\r’, num2str(u1,’%.2f’));%convert the infusion rate u1 to string, the /r is for the setting CR (Carriage Return) 
%fprintf(serobj,’rat’); %send the specific parameter you want to get from the machine.
%out=fscanf(serobj)%Scan the machine port and get the value of the specific parameter.
for j=1:n2 
Differential;
pause(1); % the pause time inbetween each calculation.
if ((t1&gt;=90)&amp;&amp;(t1&lt;=180)) %take samples of the MAP trajectory during 90s to 180s. 
N=average_slop(t3,y);% calculate the average slop of the samples to compare with a predefined range to detemine which controller should be selected.
if(Ki==-0.0005)&amp;&amp;(Kp==-0.026)
compare;
break;
elseif(Ki==-0.0018)&amp;&amp;(Kp==-0.0500)
compare2;
break;
else
compare3;
break;
end
end
end
break;
end
%use the selected controller Ki,Kp values to recalculate the infusion rate.
fprintf(serobj,’run’);
Condition;
for j=1:n2
Infusion_input;%take the calculated infusion rate u1 value.
axes(handles.axes1)
axis([0 100 90 180]);
xlabel(’time(min)’);
ylabel(’MAP(mmHg)’);
y=y0+y(1);
plot(j,y,’-.r’);
hold on;%hold the point.
axes(handles.axes2)%plot the Infusion rate vs Time
axis([0 100 0 10]);
xlabel(’time(min)’);
ylabel(’SNP Infusion Rate(mmHg/hr)’);
plot(j,u1,’-');
hold on;%hold the point.
Differential;
fprintf(serobj,’rat %s\r’, num2str(u1,’%.2f’)); %send the infusion rate to the pump if the last controller is chosen.
fprintf(serobj,’rat’);
out=fscanf(serobj)
pause(1);
end
fprintf(serobj,’stp’)
delete(serobj);

Include MATLAB code in your comment by doing the following:

<pre lang="MATLAB">

%insert code here

</pre>

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