How to vectorize nested for loops within a script

%The script:
PopList = {popCA_1,popCA_2,popCA_3,popCA_4}; % PopList is a 1 by 4 cell with 30 by 1 struct
b = [b1,b2,b3,b4]; % b is a 1 by 4 struct with 1 by 1 struct
start = false;
for d = 1:4
    lbest = b(d).Situational.accuracy;
    for f = 1:30  
          data  = PopList{d}(f); 
         
 PopList{d}(f) =newFunc(data,lbest,X,T); 
    end 
      
        PopList{d} = SortPop(PopList{d});
         
        newBeliefs = PopList{d}(1:newBeliefNo);
         
        worst = PopList{d}(nPop);
       
        b(d) = UpdateBeliefSystem(b(d), newBeliefs, worst, start);  
end
%The newFunc:
function [popdata] = newFunc(popdata,lbest,X,T)
  featSize    = size(X,2);
  cProb = 0.2; % probability of change
  nChange  = round(cProb*featSize); % number of features changed
            if (popdata.accuracy < lbest)                 
                %apply change operator (flip the values at the gene location)%                 
                 f = randperm(featSize, nChange);
                for i=1:size(f,2)
                   popdata.Position(f(i)) = mod(( popdata.Position(f(i)))+1,2);
                end
                f1 = find(popdata.Position ==1);
                popdata.nfeat = size(f1,2);
                X1 = X(:,(f1));
                %
                [popdata.accuracy, popdata.AUCval,popdata.mse,...
                    popdata.OPTROCPT,popdata.precision,popdata.F1,popdata.recall ] = knn(X1,T);
            end
end

Answer 1

[Matt J]

You cannot vectorize loops over cells and structs. In most cases, cells and structs are appropriate only for small data sizes (which appears to be your case as well), so there is usually no need to vectorize them.