MATLAB: How to create an array out of a matrix based on criteria.

embedded matlab functionMATLABmatlab function

Suppose i have a matrix of
a=[1,2; 
   1,3;
   1,4;
   2,12;
   2,15;
   5,7;
   5,8;
   6,98;
   6.99;
   7,8;
   7,9;
   7,11;
   9,14;
   9,16;
   12,18;
   14,20;
   20,35;
   98,102;
   99,204;
  204,300];
I want to create arrays arrays that will contain elements mentioned in the pair.
b=[1,2,3,4,12,15,18]
c=[5,7,8,9,14,16,20,35]
d=[6,98,99,102,204,300]
The idea is that if 2 is in a pair of 1, then every other element in pair with 2 will end up in the b array. So on and so forth for different categories, b,c,d,…. How can I achieve that kind of iteration in Matlab?

Best Answer

b = a(1,:); c = []; 
for i = 2:size(a, 1)
  if ~isempty(intersect(a(i,:), b))
    b = union(b, a(i,:));
  else
    c = union(c, a(i,:));
  end
end
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