How can I create m file with several properties?

Dear MatLab Community,

I would like to create m file function, with several optional inputs for example when I call this m function in my main code I would like to look like this:

A = myfunction(variable1, variable2, variable3,'Method',2,'Noise','RandomWalk');

or

A = myfunction(variable1, variable2, variable3,'Noise','White','Method',3);

where the property 'Method' can be 1, 2 or 3 , which assign different calculation ways for the same problem in the m files. The property 'Noise' ,let us say, can be 'white', 'randomwalk' or 'none' in the calculations. I also would like to that the default settings let be

A = myfunction(variable1, variable2, variable3);

which is equivalent the

A = myfunction(variable1, variable2, variable3,'Method',1,'Noise','None');

longer inline code.

How can i begin and implement such requirements in the m file script? Or if you can suggest a link, which deals with this implementation, I would appreciate.

Adam

Answer 1

[Julia]

Hi,

try to start with this link:

http://de.mathworks.com/help/matlab/matlab_prog/support-variable-number-of-inputs.html

Answer 2

[Guillaume]

The Mathworks way is to use inputParser:

function A = myfunction(var1, var2, var3, varargin)
   p = inputParser;
   addRequired(p, 'var1');
   addRequired(p, 'var2');
   addRequired(p, 'var3');
   addParameter(p, 'Method', 1);  %probably want a validation function as well
   addParameter(p, 'Noise', none); %probably want a validation function as well
   parse(p, var1, var2, var3, varargin{:});
   %...
end

The downside of this is that every time you call the function you have to parse / validate all inputs. If the function is repeatedly called with the same arguments. it's not efficient. My alternative, if you're familiar enough with classes, is to use function objects:

classdef myfunction
   properties
      Method = 1; %set defaults here
      Noise = 'none';
   end

     methods
       function this = set.Method(this, value)
          %do validation on method input
          this.method = value;
       end

       function this = set.Noise(this, value)
          %do validation on noise input
          this.Noise = value;
       end

      function A = run(this, var1, var2, var3)
          %do the work, using this.Noise and this.Method.
          %they're already validated, so no check needed.
      end
  end

You'd use the function object like this:

   funobject = myfunction;
   %specify non-default attribute
   funobject.Noise = 'white'
   for iter 1:1000
     A = funobject.run(var1, var2, var3);
     %the above is fast since you don't have to validate method and noise on each iteration
   end

Answer 3

[Adam]

Thank you very much your help. I am going to study your links and suggestions/solutions. Adam