Cell contents reference from a non-cell array object.

Question

mazari ahmed 2015-3-12

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/182886-cell-contents-reference-from-a-non-cell-array-object

评论： mazari ahmed 2015-4-9

 How to delete an element k in a cell array in a for loop? l have a set called neighbour_n{i} where i varies from 1 to n 
But it returns me this error :

??? Cell contents reference from a non-cell array object.

Error in ==> @(d)setxor([d{:}],[k])

Error in ==> broadcastelimination at 118 cellfun(fun, neighbour_n, 'UniformOutput', false)

neighbour_n=cell(N,1);
N = numel(neighbour_n);
for i=1:N
                 if (ismember(k, neighbour_n{i}));
                      idx = find(cell2mat(neighbour_n{i}) == k);
                       neighbour_n{i}(idx) = [];
                end
end

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mazari ahmed 2015-3-12

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l did it but it doesn't work here is my complete code :

X=100; 
Y=100;
N=200; %number of nodes 
nodesX(1)=rand*X;
nodesY(1)=rand*Y;
for i=2:N
    nodesX(i)=rand*X;
    nodesY(i)=rand*Y;
    d(i-1) =((nodesX(i)-nodesX(i-1)).^2+(nodesY(i)-nodesY(i-1)).^2).^0.5;
      while (d(i-1)>200)
         nodesX(i)=rand*X;
         nodesY(i)=rand*Y;
         d(i-1) =((nodesX(i)-nodesX(i-1)).^2+(nodesY(i)-nodesY(i-1)).^2).^0.5;
      end
end
h_old=plot(nodesX,nodesY,'m*');
labels=[1:N]';
labels=num2str(labels);
text(nodesX,nodesY,labels);
xlabel('X (Meters)');
ylabel('Y (Meters)');
title(['Network Topology with',num2str(N),'nodes']);
hold on
A= zeros(N,N);
neighbour_n=cell(N,1);
m=0;
for k=1:N;
    for j=1:N;
        if (k~=j)
        d=((nodesX(k)-nodesX(j))^2+(nodesY(k)-nodesY(j))^2)^0.5;
        end
        if (k~=j);
             if(d < 50);
            line([nodesX(k),nodesX(j)],[nodesY(k),nodesY(j)]);
            neighbour_n{k}= [neighbour_n{k} j];
            m=m+1;% the number of created links
            A(k, j)=1;
            if (A(k, j)==1);
                A(j, k)=1;
            end
              else
               A(k, j)=0;
               end
          end
      end;
      display(['the neighbours of ', num2str(k), ' are ', ' = ' , num2str(neighbour_n{k})]);
  end;
display(A);
display(['the total number of edges is: ', num2str(m)]);
deleted_node=cell(N,1);
for k=1:N;
    for j=1:N;
        if (((all(ismember(neighbour_n{k}, neighbour_n{j})))||(isequal(neighbour_n{j}, neighbour_n{k})))&&(k~=j));% incorrect syntax
            delete(line([nodesX(k),nodesX(j)],[nodesY(k),nodesY(j)]));
                display(['the line between  ', num2str(k), '  and  ',  num2str(j), '  is deleted']);
                  deleted_node{i}= [deleted_node{i} k];
                  F=Unique(deleted_node{i});
                  L=length(F);
           end  
      end
   end
      display(['the deleted nodes are ', ' = ' , num2str(F)]);
      display(['the number of deleted nodes is ', ' = ' , num2str(L)]);
eliminated_all=cell(N,1);
candidate_node=cell(N,1);
N = numel(neighbour_n);
        for i=1:N
                   result = cellfun(@(x) x(~ismember([x{:}], F)), neighbour_n, 'uniformoutput', 0);
                   display(['Display new neighbour of  ', num2str(i), ' are: ', num2str(neighbour_n{i})]);
        end

Stephen23 2015-3-13

编辑：Stephen23 2015-3-13

I have no idea what "it doesn't delete the values" means.

The setdiff documentation states "setdiff(A,B) returns the data in A that is not in B."

This means if you still have values in the output that you do not expect to have then the you need to check that the input values are correct. If an element of A is not in B then it will be in the output.

And I note that the cyclist is also giving advice on your original question here:

http://www.mathworks.com/matlabcentral/answers/182868-delete-an-element-in-a-cell-array-in-a-for-loop

Which is a good example of why I said at the start of this thread that you should not ask new questions about the same topic, but you should keep communicating on the same thread until the topic is resolved.

mazari ahmed 2015-3-13

编辑：mazari ahmed 2015-3-13

在 MATLAB Online 中打开

l think the problem is in the last instruction it deletes the values but doesn't update the the neighbour_n when it displays.?

display(['Display new neighbour of  ', num2str(i), ' are: ', num2str(neighbour_n{i})]);

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Answer 1

mazari ahmed 2015-3-14

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/182886-cell-contents-reference-from-a-non-cell-array-object#answer_171326

在 MATLAB Online 中打开

the answer is :

neighbour_n{i}= setdiff(neighbour_n{i},F);

problem solved

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Answer 2

Image Analyst 2015-3-13

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/182886-cell-contents-reference-from-a-non-cell-array-object#answer_171155

在 MATLAB Online 中打开

Not sure what's going on in your parallel discussion, but if you have a cell array called neighbour and you want to delete the k'th cell from that cell array, you can do this:

neighbour_n(k) = []; % Note parentheses, not braces.

You don't need to put it in a loop. See the FAQ: http://matlab.wikia.com/wiki/FAQ#What_is_a_cell_array.3F to get a better intuitive feeling for cell arrays.

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mazari ahmed 2015-3-13

在 MATLAB Online 中打开

no for exemple l have n = 3 so neighbours_n{1}={1,4,7,8} neighbours_n{2}={1,7,9,13,27} neighbours_n{3}={8,4,7,12} and k= {4,7,12,27} if ismember(k,neighbours_n{i}) neighbours_n{1}={1,7,8} neighbours_n{2}={1,9,13} neighbours_n{3}={8}.

My problem right now is how to update the display of the neighbours after the execution ,it displays the initial values of neighbours_n{i} how to update that? here is my code

   X=100; 
  Y=100;
  N=200; %number of nodes 
  nodesX(1)=rand*X;
  nodesY(1)=rand*Y;
for i=2:N
    nodesX(i)=rand*X;
    nodesY(i)=rand*Y;
    d(i-1) =((nodesX(i)-nodesX(i-1)).^2+(nodesY(i)-nodesY(i-1)).^2).^0.5;
        while (d(i-1)>200)
           nodesX(i)=rand*X;
           nodesY(i)=rand*Y;
           d(i-1) =((nodesX(i)-nodesX(i-1)).^2+(nodesY(i)-nodesY(i-1)).^2).^0.5;
        end
end
h_old=plot(nodesX,nodesY,'m*');
labels=[1:N]';
labels=num2str(labels);
text(nodesX,nodesY,labels);
xlabel('X (Meters)');
ylabel('Y (Meters)');
title(['Network Topology with',num2str(N),'nodes']);
hold on
A= zeros(N,N);
neighbour_n=cell(N,1);
m=0;
for k=1:N;
    for j=1:N;
        if (k~=j)
        d=((nodesX(k)-nodesX(j))^2+(nodesY(k)-nodesY(j))^2)^0.5;
        end
        if (k~=j);
             if(d < 50);
            line([nodesX(k),nodesX(j)],[nodesY(k),nodesY(j)]);
            neighbour_n{k}= [neighbour_n{k} j];
            m=m+1;% the number of created links
            A(k, j)=1;
            if (A(k, j)==1);
                A(j, k)=1;
            end
                else
                 A(k, j)=0;
                 end
            end
        end;
        display(['the neighbours of ', num2str(k), ' are ', ' = ' , num2str(neighbour_n{k})]);
    end;
display(A);
display(['the total number of edges is: ', num2str(m)]);
deleted_node=cell(N,1);
for k=1:N;
    for j=1:N;
        if (((all(ismember(neighbour_n{k}, neighbour_n{j})))||(isequal(neighbour_n{j}, neighbour_n{k})))&&(k~=j));% incorrect syntax
            delete(line([nodesX(k),nodesX(j)],[nodesY(k),nodesY(j)]));
                  display(['the line between  ', num2str(k), '  and  ',  num2str(j), '  is deleted']);
                    deleted_node{i}= [deleted_node{i} k];
                    F=Unique(deleted_node{i});
                    L=length(F);
             end  
        end
     end
        display(['the deleted nodes are ', ' = ' , num2str(F)]);
        display(['the number of deleted nodes is ', ' = ' , num2str(L)]);
eliminated_all=cell(N,1);
candidate_node=cell(N,1);
N = numel(neighbour_n);
          for i=1:N
                     result = cellfun(@(x) x(~ismember([x{:}], F)), neighbour_n, 'uniformoutput', 0);
                     display(['Display new neighbour of  ', num2str(i), ' are: ', num2str(neighbour_n{i})]);
          end

Image Analyst 2015-3-13

Sorry - it's too late at night for me to delve into all that. I suggest you keep at it with your original thread.

mazari ahmed 2015-4-9

Problem solved

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Cell contents reference from a non-cell array object.

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