Changing system preferences programmatically

June 17, 2009 17 Comments

My very first post on this blog showed how to change Matlab’s command-window colors. In that post I promised to write another post detailing how system preferences can be changed from the command line.
Last week I wrote about undocumented GUIDE features. After my initial post, I realized that I forgot to mention all the different relevant system preferences that can also be modified. I therefore modified last week’s post with the preferences information. I now wish to finally detail how such preferences can be changed programmatically, from within your Matlab application or from the Matlab desktop command prompt.
Matlab’s user preferences are stored in the matlab.prf text file which is stored in the user’s Matlab preferences folder:

edit(fullfile(prefdir,'matlab.prf'));

Each preference appears to be on a separate line in the following format: <pref-name>=<pref-type><pref-value>
where <pref-type> appears to be one of these:

‘B’ => boolean/logical flag
‘C’ => color (RGB numeric value)
‘F’ => font (type,size,name)
‘I’ => int16
‘J’ => int64
‘R’ => rectangular area (x,y,h,w)
‘S’ => string/char

Examples:
EditorShowLineNumbers=Btrue
EditorMaxCommentWidth=I120
You can read the preference names from this matlab.prf file and then use the following (you-guessed-it) java calls to get/set the values:

com.mathworks.services.Prefs.get<type>Pref(<pref-name>)
com.mathworks.services.Prefs.set<type>Pref(<pref-name>, newValue);

where <type> is one of: Boolean, Color, RGBColor, Font, Integer, Rectangle, String, Double (I believe Doubles get converted to int64 – possibly a bitwise casting since both use 64 bits)
For example:

com.mathworks.services.Prefs.getBooleanPref('LayoutSnapToGrid')
com.mathworks.services.Prefs.setIntegerPref('LayoutGridWidth', 25)

adding a second argument to get<type>Pref() appears to indicate a default value that is returned if <pref-name> is not defined:

com.mathworks.services.Prefs.getIntegerPref('xxxx',123)
=> 123

We can programmatically set any preference key we like – we are not limited to Matlab’s built-in set. I used this feature in my CPRINTF utility, to set user-defined colors for later use by the desktop’s UI syntax-highlighting engine. The relevant code segment is this:

% Convert a Matlab RGB vector into a known style name (e.g., '[255,37,0]')
function styleName = getColorStyle(rgb)
  % Convert Matlab RGB array into a Java Color object
  intColor = int32(rgb*255);
  javaColor = java.awt.Color(intColor(1), intColor(2), intColor(3));
  % Preference key name format: '[RRR,GGG,BBB]'
  styleName = sprintf('[%d,%d,%d]',intColor);
  % Set/update the preference with this Java Color
  com.mathworks.services.Prefs.setColorPref(styleName,javaColor);

…which in turn adds entries such as the following to my matlab.prf file:
[12,34,67]=C-15982013
Note that -15982013 = 0xFF0C2243, which is the RGB value [12,34,67] with an opaque alpha value. This value can later be retrieved using:

>> com.mathworks.services.Prefs.getColorPref('[12,34,67]')
ans =
java.awt.Color[r=12,g=34,b=67]

Warning: I published much of this information on the CSSM forum back in 2007. Ben Steiner then shared his experience on that thread that:
For anyone else that’s playing with this: I don’t advise trying to edit the matlab.prf via matlab(!). I created a situation that made Matlab unworkable. I did find that deleting the matlab.prf completely (in frustration) solved it.
Take a look at your matlab.prf file – can you spot any interesting preference? If so, please share it in the comments section below.

Desktop Java

17 Responses

Undocumented feature() function | Undocumented Matlab May 4, 2010 at 09:21 Reply

[…] feature(’GetPref’,prefName) – returns the system preference value for the requested preference name in the global prefs file ([prefdir,’matlab.prf’]) that is explained here. […]
Shaul February 2, 2011 at 08:07 Reply

Hi Yair,

I work on multiple projects at the same time and I like to have multiple matlab instances open on my computer, one for each project (I realize this might not be a particularly smart way to work). However, I would like each of them to save to a different command window history file. Is there a good safe way to do this?

Thanks! All the best,
Shaul

Yair Altman February 2, 2011 at 09:54 Reply

@Shaul – I do not know a way to customize the history file path

Paul May 25, 2011 at 13:33 Reply

Is there a way to programmatically update the Simulink preferences, such as the Autosave option?

Thanks,

paul

Yair Altman May 25, 2011 at 13:38 Reply

@Paul – I’m sure there is, but I don’t know…

Chad Gilbert January 10, 2012 at 12:13 Reply

Hi Yair,

It seems that after doign this, I need to re-start MATLAB before the changes take effect. Do you know of any better way to make my changes “kick in”?

Yair Altman January 10, 2012 at 12:56 Reply

@Chad – there is a com.mathworks.services.Prefs.load() method, but I think it will not help you much because I think that most preferences are loaded and used during startup, not dynamically.

Jonas November 14, 2012 at 15:56 Reply

I just learned once more that it’s extremely helpful to programmatically check for the correct “MatfileSaveFormat” property to avoid being unable to save (or later: load) your results. Thanks for your helpful post!

Oleg Komarov October 13, 2014 at 03:08 Reply

To change Parallel Pool settings:

ps = parallel.Settings;
ps.Pool
ans = 
  PoolSettings with properties:
                            AutoCreate: 0
                RestartOnClusterChange: 1
    RestartOnPreferredNumWorkersChange: 1
                           IdleTimeout: 30
                   PreferredNumWorkers: 12

Yair Altman October 13, 2014 at 04:24 Reply

To complete the picture:

>> ps = parallel.Settings
ps = 
 Parallel Settings Information
       DefaultProfile: local
 
    Profiles and Components: 
 
             Profiles: [1x1 parallel.settings.Profile]
  SchedulerComponents: [1x1 parallel.settings.schedulerComponent.Local]
    ProjectComponents: [0x0 parallel.settings.ProjectComponent]
 
>> getundoc(ps)
ans = 
            ConfigsMcrUserDataKey: 'ParallelConfigurationFile'
    ConfigurationsLastUpgradeTime: '???'
    DefaultProfileChangedListener: [1x1 event.proplistener]
          DefaultProfileListeners: [1x2 event.listener]
             DefaultProfileObject: [1x1 parallel.settings.Profile]
           DummyEnforceInitClient: 'BMPA'
                 ImportNameSuffix: '_Import'
         LastUpgradeSettingsLevel: [1x1 parallel.internal.types.SettingsLevel]
                 LocalProfileName: 'local'
            McrUserDataNameSuffix: '_mcruserdata'
                       NodeFacade: [1x1 parallel.internal.settings.SettingsNodeFacade]
                             Pool: [1x1 parallel.internal.settings.PoolSettings]
               ProfilesCollection: [1x1 parallel.internal.settings.NamedNodesCollection]
           ProfilesMcrUserDataKey: 'ParallelProfile'
      ProjectComponentsCollection: [1x1 parallel.internal.settings.NamedNodesCollection]
    SchedulerComponentsCollection: [1x1 parallel.internal.settings.TypedNodesCollection]
         UsingDeployedCollections: 0

Scott Lowe November 8, 2015 at 21:00 Reply

Hi Yair,

Thanks for this article!

I took inspiration from it to create a package to import and export color schemes in MATLAB. This definitely would not have been possible without undocumentedmatlab!

It is available on GitHub and FileExchange.

All the best,
Scott
jon May 13, 2016 at 20:06 Reply

Thank you!
Parvaneh September 28, 2016 at 13:59 Reply

Hi Yair,

I was looking for a way to change the setting of the system using matlab when I saw this post.
I wonder if you can help me with it.
I’m connecting two monitors and I want to run a program from one monitor and make it run on the other one.
In the process I need to change setting from ‘screen resolution’ in the control panel.
Could this be done with matlab?

I would appreciate any help.

Thanks,
Parvaneh

Yair Altman September 28, 2016 at 14:09 Reply

@Parvaneh – you will need to check the web for a utility that has a command-line interface that does what you want, and then you can call that utility from Matlab using the system command.

Mohit May 22, 2020 at 15:11 Reply

Hi Yair,
I am trying to change keybindings to certain keys for many systems is there any way that we can change these settings.
i can change in window dialogue like Home>Environment>Preferences>keyboard>Shortcuts > then i select shortcut and change ….can we do it through code like above ? I tried many things but didn’t able get it to work
Robin October 30, 2020 at 14:49 Reply

Hi Yair,

This has been a great help.
With the removal of com.mathworks sometime in the future (as announced in R2020b), is there an alternative?
For me, just getting a preference value programmatically would be enough. I am not interested in setting them.

Thanks,
Robin
François June 2, 2023 at 17:51 Reply

more than 10 years later it helps me after struggling few hours, so thanks you very much !

HTML tags such as <b> or <i> are accepted.
Wrap code fragments inside <pre lang="matlab"> tags, like this:

<pre lang="matlab">
a = magic(3);
disp(sum(a))
</pre>

I reserve the right to edit/delete comments (read the site policies).
Not all comments will be answered. You can always email me (altmany at gmail) for private consulting.

Click here to cancel reply.

Related posts:

17 Responses

Leave a Reply