calling dependent properties from one class to another

Question

kanuri venkata mohana 2020-9-10

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/591730-calling-dependent-properties-from-one-class-to-another

回答： Steven Lord 2020-9-11

Hi guys,

I want to call dependent properties from one class to another in matlab OOP. Could anyone suggest me how to do that.

I just want to call all my dependent properties. Since i calculated them using get function iam unable to understand how to call them. Could anyone give me some idea.

Thankyou

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Steven Lord 2020-9-10

Are you trying to access the dependent properties through the class name or through a class instance?

The people class defines properties height and weight and a dependent property bodyMassIndex calculated from height and weight.

It doesn't make sense to ask for the bodyMassIndex for the people class.

It makes sense to ask for the bodyMassIndex of a specific instance of the people class.

If that's not the difficulty you're experiencing trying to access dependent properties, please show a small example that simulates the real problem you're trying to solve/model and explain the difficulty using that small example.

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Answer 1

Matt J 2020-9-10

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/591730-calling-dependent-properties-from-one-class-to-another#answer_492661

编辑：Matt J 2020-9-10

在 MATLAB Online 中打开

You access it the same as you would a non-Dependent property,

object.property

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kanuri venkata mohana 2020-9-11

编辑：Matt J 2020-9-11

在 MATLAB Online 中打开

classdef clCore
    properties(GetAccess=?fitFunction)
        depth
        length
        Matcore
        Wm
    end
    properties(Dependent)
        area
    end
    methods
        function obj=clCore(depth,length,Matcore)
            obj.depth=depth;
            obj.length=length;
            obj:Matcore=Matcore;
            end
        function area=get.area(obj)
            area=obj.depth*obj.length
            
        end
    end
    
end

objCore=clCore(4,5,1)

classdef Designspec
    properties
      Matcore  
      Wm=1
      dxma=1.5;
    end
    methods
        function obj=Designspec(Matcore)
           obj.Matcore=Matcore; 
        end
    end
end

objDS=Designspec(1);

classdef fitFunction
    methods(Static)
        function f=fit(objDS)
            P=[0.456,0.2030]
            objCore.Matcore=objDS.Matcore;
            objCore.Wm=objDS.Wm;
            
            % my core parameters have to be updated
            objCore.depth=P(1);
            objCore.length=P(2);
            
            % i need to call my dependent properties
            c1=lte(objCore.depth,objDS.dxma)
        end
    end
end

objfit=fitFunction;

f=objfit.fit(p;objDS)

function [c]=lte(x,xmxc)
% lte          less than or equal to function. Returns 1 if the 
%              argument is less than or equal to the allowed value, 
%              otherwise it returns a value between 0 and 1.
%
% Call:
% c=lte(x,xmxc)
%
% Inputs
%  x         = value to be tested
%  xmxc      = maximum value of x which passes constraint
%
% Output
%  c         = constraint value
    if (x>xmxc)
        c=1/(x-xmxc+1);
    else
        c=1;
    end

This is a simple example but i still have lot of parameters. i just explained with 2 to 3 parameters. My question is in class fitFunction i want to access dependent parameters from clCore when i was trying to do that it always says reference to non-existenet field so i tried giving

function f=fit(objDS,objCore)

instead of

function f=fit(objDS)

It worked but i need to give this fitfunction in Genetic algorithm where i could use only objDS as input but not objCore.

here is my genetic algorithm program

 classdef cl_UI_GA
    properties
       
        dv_act=0;
        rp_lvl=1;
        ev_pp=true;
        mg_nreg=10;
    end
    methods(Static)
        function [obj,fP,GAS,bi,bf]=GA1(objDS)           % set up GA
            ngen=50;
            npop=50;
            obj=gapdefault(2,0,npop,ngen);
            
            
            % gene description
            %         min   max chrm  chrm      par
            %         val   val type   id        #         description
            obj.gd= [  1     4    1    1;  ...  %  depth
                1     2    1    1]   %  2  length
               
            
            for i=1:2
                
                objDS.Wm = i;
                
                for k = 1:3
                    
                    objDS.Matcore=k;
                    %                     objT.Tm=1;
                    
                    %FOIL:
                    if objDS.Wm==2
                        %Design Space for Foil Winding Model:
                        obj.gd= [obj.gd;
                            
                        1e-2    1    3    1; ... %  11  hf - foil winding height(m)
                        0.1*1e-3 3*1e-3  3    1]; ...%  12  wf - foil winding width(m)
                        
                    
                    % conduct optimization
                    [fP,GAS,bi,bf]= gaoptimize(@fitFunction.fit,obj,objDS);
                    % save the results
                    if objDS.Matcore==1
                        s2='IndFoil_';
                        s3='Steel_';
                        filename=strcat(s2,s3);
                        save (filename)
                    
                    else
                        disp('No such material catalog for core');
                    end
                    
                    %LITZ:
                    else
             % go to Litz fit
    end
end

objGAP=cl_UI_GA;
[objGAP,fP,GAS,bi,bf]=objGAP.GA1(objDS)

and when i am trying to run the program my algorithm is not converging it is just showing some constant value for the number of genertions i have generations. It could be 50 or 100 my fitness value is not changing.

Could anyone help me.

Thankyou

Matt J 2020-9-11

So, it's a different problem now? Earlier you said you were getting an error message about a non-existent property reference.

kanuri venkata mohana 2020-9-11

i described about the different cases of my error. i have also explained about the non-existent field property reference and also the way i tried.

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Answer 2

Steven Lord 2020-9-11

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/591730-calling-dependent-properties-from-one-class-to-another#answer_493183

在 MATLAB Online 中打开

classdef fitFunction
    methods(Static)
        function f=fit(objDS)
            P=[0.456,0.2030]
            objCore.Matcore=objDS.Matcore;
            objCore.Wm=objDS.Wm;
            
            % my core parameters have to be updated
            objCore.depth=P(1);
            objCore.length=P(2);
            
            % i need to call my dependent properties
            c1=lte(objCore.depth,objDS.dxma)
        end
    end
end

You created an object objCore in the base workspace. This function does not operate on that object. The assignments to objCore make a struct array in this function's workspace. So if you were to ask for objCore.area in this function, that struct doesn't have a field by that name.

There's a scientist named Steven Lord at the SETI Institute. Even though we share a name, I am not him and he is not me. Similarly just because the object in the base workspace and this identifier in the function share a name, they are not the same thing.

If you want this function to operate on an objCore object, it needs to accept that object as an input or to create one. [Technically there is a way for it to "reach into" its caller's workspace or the base workspace, but I strongly discourage doing that sort of "action at a distance".]