How to solve the problem ?

Question

Akash Pal 2022-5-12

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1717555-how-to-solve-the-problem

评论： Jan 2022-5-13

function [F,front,Q, individual,index_of_objectives, f,temp,index_of_fronts,sorted_based_on_front,sorted_based_on_objective,y,next_obj, f_max, f_min,previous_obj, distance,z] = non_domination_sort_mod(comb10a, M, V)
[N, m2] = size(comb10a);
clear m2
% Initialize the front number to 1.
front = 1;
F(front).f = [];
individual = [];
for i = 1 : N
    % Number of individuals that dominate this individual
    individual(i).n = 0;
    % Individuals which this individual dominate
    individual(i).p = [];
    for j = 1 : N
        dom_less = 0;
        dom_equal = 0;
        dom_more = 0;
        for k = 1 : M
            if (comb10a(i,V + k) < comb10a(j,V + k))
                dom_less = dom_less + 1;
            elseif (comb10a(i,V + k) == comb10a(j,V + k))
                dom_equal = dom_equal + 1;
            else
                dom_more = dom_more + 1;
            end
        end
        if dom_less == 0 && dom_equal ~= M
            individual(i).n = individual(i).n + 1;
        elseif dom_more == 0 && dom_equal ~= M
            individual(i).p = [individual(i).p j];
        end
    end
    if individual(i).n == 0
        comb10a(i,M + V + 1) = 1;
        F(front).f = [F(front).f i];
    end
end
% Find the subsequent fronts
while ~isempty(F(front).f)
   Q = [];
   for i = 1 : length(F(front).f)
       if ~isempty(individual(F(front).f(i)).p)
        	for j = 1 : length(individual(F(front).f(i)).p)
            	individual(individual(F(front).f(i)).p(j)).n = ...
                	individual(individual(F(front).f(i)).p(j)).n - 1;
        	   	if individual(individual(F(front).f(i)).p(j)).n == 0
               		comb10a(individual(F(front).f(i)).p(j),M + V + 1) = ...
                        front + 1;
                    Q = [Q individual(F(front).f(i)).p(j)];
                end
            end
       end
   end
   front =  front + 1;
   F(front).f = Q;
end
[temp,index_of_fronts] = sort(comb10a(:,M + V + 1));
for i = 1 : length(index_of_fronts)
    sorted_based_on_front(i,:) = comb10a(index_of_fronts(i),:);
end
current_index = 0;
for front = 1 : (length(F) - 1)
%    objective = [];
    distance = 0;
    y = [];
    previous_index = current_index + 1;
    for i = 1 : length(F(front).f)
        y(i,:) = sorted_based_on_front(current_index + i,:);
    end
    current_index = current_index + i;
    % Sort each individual based on the objective
    sorted_based_on_objective = [];
    for i = 1 : M
        [sorted_based_on_objective, index_of_objectives] = ...
            sort(y(:,V + i));
        sorted_based_on_objective = [];
        for j = 1 : length(index_of_objectives)
            sorted_based_on_objective(j,:) = y(index_of_objectives(j),:);
        end
        f_max = ...
            sorted_based_on_objective(length(index_of_objectives), V + i);
        f_min = sorted_based_on_objective(1, V + i);
        y(index_of_objectives(length(index_of_objectives)),M + V + 1 + i)...
            = Inf;
        y(index_of_objectives(1),M + V + 1 + i) = Inf;
         for j = 2 : length(index_of_objectives) - 1
            next_obj  = sorted_based_on_objective(j + 1,V + i);
            previous_obj  = sorted_based_on_objective(j - 1,V + i);
            if (f_max - f_min == 0)
                y(index_of_objectives(j),M + V + 1 + i) = Inf;
            else
                y(index_of_objectives(j),M + V + 1 + i) = ...
                     (next_obj - previous_obj)/(f_max - f_min);
            end
         end
    end
    distance = [];
    distance(:,1) = zeros(length(F(front).f),1);
    for i = 1 : M
        distance(:,1) = distance(:,1) + y(:,M + V + 1 + i);
    end
    y(:,M + V + 2) = distance;
    y = y(:,1 : M + V + 2);
    z(previous_index:current_index,:) = y;
end
f = z();
end

i am following this coding to find out the non dominated sorting and the crowding distance of my matrix comb10a ,where M is th objective function and V is the decision variables .But every time in the line of 
[temp,index_of_fronts] = sort(comb10a(:,M + V + 1));
this i am getting one error 

Index in position 2 exceeds array bounds (must not exceed 12).

Error in non_domination_sort_mod1wed (line 58)

[temp,index_of_fronts] = sort(comb10a(:,M + V + 1));

Error in mainnsga2 (line 34)

[F,front,Q, individual,temp,index_of_fronts,sorted_based_on_front,f] = non_domination_sort_mod1wed(comb10a, M, V)

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Akash Pal 2022-5-13

Yes i can simplify it ,but still i have the same error .I dont understand why its happening when i am running this function in a loop .

Jan 2022-5-13

If the code is simplified, it is much easier to debug. Obviously the code produces an error, because the loop let it use an index outside the existing range. There is no magic workaround but you have to check the indices to find out, why M + V + 1 > columns .

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Answer 1

Image Analyst 2022-5-12

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1717555-how-to-solve-the-problem#answer_962605

在 MATLAB Online 中打开

Put these lines in

[rows, columns] = size(comb10a)
if M + V + 1 > columns
    errorMessage = sprintf('Hey! The matrix comb10a has only %d columns but you are trying to sort column #%d!, which does NOT exist!', columns, M + V + 1)
    uiwait(errordlg(errorMessage));
    return;
else
    [temp,index_of_fronts] = sort(comb10a(:, M + V + 1);
end

Now what do you see?

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Akash Pal 2022-5-13

编辑：Akash Pal 2022-5-13

I got this error ,actually by the code ,we try to assign the nondominated rank in a new column and i guess based on that rank or the column number , it is sorting first and then finding the crowding distance of each fronts .

when i am doing the steps manually step by step that time its working properly but when i am giving it in a loop its showing me this result .

so what to do next ?

Image Analyst 2022-5-13

I'd go over the debugging training in this link

Debugging in MATLAB | Doug's MATLAB Video Tutorials

so you can learn how to step through your code and figure out how/why you're trying to sort on column 13 when there are only 12 columns in the matrix.

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How to solve the problem ?

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