Storing and comparing data after performing parfor with basic class function

Dear forum,

My goal is to compare diferent energy specta after they have been modified using a class function. I first setup a energy spectrum for my first function f(1). I then generate three addition functions f(2),f(3),f(4). These are then sent into the classdef for analysis. Once the parfor is completed I output the four different spectra in the command window. However, I unable to save these to the workspace for additional analysis. Here is my simple example.

This is my main function:

Test(10,1,10)
function Test(Emax,Emin,nodesE)
      
    originalY=zeros(11,2);
    for i=1:nodesE
      originalY(i,1)=i*(Emax-Emin)/10+Emin;
      originalY(i,2)=ones(length(nodesE),1);
    end
    
      fit(1)=masterFitTestObj(nodesE);
      fit(1).nodeSpectrumE(:,1)=originalY(1:nodesE,1);
      fit(1).nodeSpectrumE(:,2)=originalY(1:nodesE,2);
      
      nodesE=nodesE+1;
    for thread=2:4
      fit(thread)=masterFitTestObj(nodesE);
      fit(thread).nodeSpectrumE(:,1)=originalY(1:nodesE,1);
      fit(thread).nodeSpectrumE(:,2)=originalY(1:nodesE,2);
    end
      
    parfor thread=1:4
        fit(thread).run()
        fit(thread).spectrumE
    end

    
end   

I first make an x-y (2x10) pair (originalY) then generate three x-y pairs with one more value for each (2x11). I then just change the y-values for each in the classdef code:

classdef masterFitTestObj < handle
  
    properties
        Emin=1.0;
        spectrumE=zeros(20,2);
        nodeSpectrumE=[];
    end
    
    methods
        function obj=masterFitTestObj(nodesE)
        obj.spectrumE=zeros(20,2);
        obj.nodeSpectrumE=zeros(nodesE,2);

        for i=1:20
            obj.spectrumE(i,1)=i*0.5+obj.Emin;
        end
        
        end
        
   function run(obj)  

      spectrumE_int = interp1(obj.nodeSpectrumE(:,1),obj.nodeSpectrumE(:,2),obj.spectrumE(:,1));
      spectrumE_int(isnan(spectrumE_int))=0;
      obj.spectrumE(:,2) = spectrumE_int+rand(20,1);
      
   end
   end
    
end

The goal is to compare the four different x-y pairs of spectrumE once parfor is done. I am able to have these prinited in the command window with the following:

fit(thread).spectrumE

However, I am unable to save these to the workspace. Is there a way to save the four different spectra to the workspace?

Any help is appreaciated.

~CJ

Answer 1

[Aditya]

Hi Chad,

I understand that you are looking to store the results from each “spectrum” after processing them in a “parfor loop” so that you can work with them in the MATLAB workspace for further analysis.

You can store your results from each “spectrum” into an array or cell array and then pass it to the workspace using different methods:

1. Output Arguments:

You can modify your function to return the results as an output argument. Here's a snippet using a cell array to store the spectra:

function spectraCell = Test(Emax, Emin, nodesE) 
    % ... (your existing code) 
    
    spectraCell = cell(1, 4); % Pre-allocate cell array for the spectra 
    parfor thread=1:4 
        fit(thread).run(); 
        spectraCell{thread} = fit(thread).spectrumE; % Store the spectrum in the cell array 
    end 
end 

You can then call it from the workspace:

spectraCell = Test(10,1,10); 

2. Assignin Function:

If you prefer not to modify the function signature, you can use “assignin” within your function to pass the spectra directly to the workspace:

function Test(Emax, Emin, nodesE) 
    % ... (your existing code) 
    
    spectraCell = cell(1, 4); % Pre-allocate cell array for the spectra 
    parfor thread=1:4 
        fit(thread).run(); 
        spectraCell{thread} = fit(thread).spectrumE; % Store the spectrum in the cell array 
    end 
    
    assignin('base', 'spectraCell', spectraCell); 
end 

3. Save to File:

Another approach is to save the data into a file using the “save” function, and then you can load it whenever necessary:

function Test(Emax, Emin, nodesE) 
    % ... (your existing code) 
    
    spectraCell = cell(1, 4); % Pre-allocate cell array for the spectra 
    parfor thread=1:4 
        fit(thread).run(); 
        spectraCell{thread} = fit(thread).spectrumE; % Store the spectrum in the cell array 
    end 
    
    save('spectraCell.mat', 'spectraCell'); 
end 

Then, in the workspace, you can load the data:

load('spectraCell.mat'); 

For more information on “assignin” function, refer to the MATLAB documentation here:

• https://www.mathworks.com/help/releases/R2019b/matlab/ref/assignin.html?s_tid=doc_ta

Hope this resolves your issue!