Question on ismembc and any function

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jana 2014-2-26

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https://ww2.mathworks.cn/matlabcentral/answers/119240-question-on-ismembc-and-any-function

评论： jana 2014-2-26

Hi, I am having a problem using the ismembc and any function. Here's the code that I wrote:

while ~isempty(XH{i})
L = false(n, n);
seccost = zeros(n, n);
for ii = 1:n
    for jj = 1:n
        L(ii,jj) = any((ismembc(XH{i},Sc{ii,jj}))); % my problem function!!!
        if L(ii,jj) == 1
              seccost(ii,jj)  = costs(ii,jj);
              seccost(i,j) = 0;
              seccost(j,i) = 0;
          else 
               seccost(ii,jj)  = 0;
      end
      end
  end
end

this works fine for small values of n, however as n increases (n = 3000), my code takes a lot of time. I've to use seccost matrix thus generated to calculate the shortest path using graphshortetspath function. I was wondering if you have a better idea to increase the efficiency of my code. I was initially using ismember function, but I changed it to ismembc function as it is faster. But it is still not helping.

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Answer 1

Jan 2014-2-26

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https://ww2.mathworks.cn/matlabcentral/answers/119240-question-on-ismembc-and-any-function#answer_126260

编辑：Jan 2014-2-26

在 MATLAB Online 中打开

Omit overwriting zeros by zeros:

L       = false(n, n);
seccost = zeros(n, n);
for ii = 1:n
  for jj = 1:n
  L(ii,jj) = any((ismembc(XH{i},Sc{ii,jj}))); % my problem function!!!
  if L(ii,jj) == 1
    seccost(ii,jj) = costs(ii,jj);
  end
end

How large are the elements of XH and Sc?

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jana 2014-2-26

Jan,

XH is a cell array of size 1xn where n = 3000 and Sc is of size n x n with n = 3000 and it is again a cell array. Both of these variables contain a set of numbers example: XH{1} = [1,2,3] and Sc{1,2} = [1,3,4]. I dont think by omitting overwriting zeros by zeros is going to help much. Is there a better way of writing the above code. I am new to matlab and this was the best I could think of.

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