Conditional properties in classdefs

Hello,

I am new to MATLAB and object-oriented programming. I am working with a class which has the following property:

classdef DataML < ModelData
  properties
    nest_ID = [ 1 1 2 2 3 ]; % current model
    % nest_ID = [1 2 2 2 3], % alternative model specification 
    % nest_ID = [1 1 1 2 3]) % alternative model specification 
    nest_index = [1,2,3,4]; % current model
    nest_index = [2,3,4]; % alternative model specification
    nest_index = [1,2,3]; % alternative model specification
  end
end

I have to run my model for several values of nest_ID (e.g. %nest_ID = [1 2 2 2 3], nest_ID = [1 1 1 2 3]). nest_index is a variable that depends on nest_ID and hence needs to be defined conditionally depending on the value of nest_ID. I want to make my class more flexible: depending on the value of the nest_ID array, I want nest_index to take different values. I tried the following code with if else conditions but I get a syntax error saying that I cannot include conditional statements in class properties.

    classdef DataML < ModelData
      properties
        nest_ID = [ 1 1 2 2 3 ]; % current model
        % nest_ID = [1 2 2 2 3], % alternative model specification 
        % nest_ID = [1 1 1 2 3]) % alternative model specification 
        if nest_ID = [ 1 1 2 2 3 ]
          nest_index = [1,2,3,4]; % current model
        elseif if nest_ID = [1 2 2 2 3] % alternative model specification
          nest_index = [2,3,4]; 
        elseif if nest_ID = [1 1 1 2 3] % alternative model specification
          nest_index = [1,2,3];  
        end
      end
    end

Can you please advice how I can do this?

Many thanks, Mihir

Answer 1

[per isakson]

Try put the calculations in the constructor and provide the model ID as input

classdef    DataML < ModelData
    properties
        nest_ID
        nest_index
    end
    methods     
        function this = DataML( id )

              if all( id == [ 1 1 2 2 3 ] )
                  this.nest_index = [1,2,3,4]; 
              elseif all( id == [1 2 2 2 3] ) 
                  this.nest_index = [2,3,4];
              elseif all( id == [1 1 1 2 3] ) 
                  this.nest_index = [1,2,3];
              else
                  error('Unknown input value') 
              end
              this.nest_ID = id;
          end
      end
  end

[Mihir Sharma]

Great, thanks a lot, that worked! I have a followup question. I have another class called ModelML. Can I define objects in ModelML using conditional statements based on the values of objects that I have defined in DataML? For instance:

    classdef ModelML 
      properties
      paramlist

      methods
        function inds = get.paramlist(nest_ID )
          if nest_ID == [ 1 2 2 2 3 ]
            inds = {'sigma'}
          end
        end
      end
    end

How can I call objects from DataML when I'm in ModelML?

[per isakson]

See

• Property Access Methods
• Comparison of Handle and Value Classes

[per isakson]

Try

>> mml = ModelML
mml = 
  ModelML with properties:

      paramlist: [1 2 3 4 5 6]
  >> mml.get_paramlist([1,1,1,2,3])
       1     2     3
  ans =
       1     2     3     4     5     6

where

classdef    DataML < handle % ModelData
    properties
        nest_ID
        nest_index
    end
    methods     
        function this = DataML( id )

                if all( id == [ 1 1 2 2 3 ] )
                    this.nest_index = [1,2,3,4]; 
                elseif all( id == [1 2 2 2 3] ) 
                    this.nest_index = [2,3,4];
                elseif all( id == [1 1 1 2 3] ) 
                    this.nest_index = [1,2,3];
                else
                    error('Unknown input value') 
                end
                this.nest_ID = id;
            end
      end
  end

and

classdef ModelML
    properties
        paramlist = [1,2,3,4,5,6];
    end
    methods
        function  inds = get_paramlist( this, nest_ID )
            if all( nest_ID == [ 1 2 2 2 3 ] )
                inds = {'sigma'};
            else
                inds = this.paramlist;
            end
            data_model = DataML( nest_ID );
            disp( data_model.nest_index )
        end
    end
end