MATLAB: How to find the indices of the repeating elements in an array with respect to another array

data manipulationecgintersectismembersignal processing

I am using MATLAB R2016a version.Here is an example which explains my question.
   a=[1,2,3,3,4,5,5,7,8,2] ;
   b=[1,2,3,3,2,4,5,5] ;
   [x,y]=ismember(b,a);
The output y is :
      y=[1,2,3,3,2,4,5,5]
Whereas,I want the output to be:
    y=[1,2,3,4,10,5,6,7]
I want the elements of b to be expressed in terms of indices of a,including the repeating elements. In ismember the indices of the repeated elements are repeated.
Any suggestions?

Best Answer

Here is a simple for-loop approach:
a=[1,2,3,3,4,5,5,7,8,2] ;
b=[1,2,3,3,2 2 2,4,5,5 999] ; % see my comments above
y = zeros(size(b)) ;
for bu = unique(b)
    ib = find(b==bu) ;
    ia = find(a==bu) ;
    n = min(numel(ia),numel(ib)) ;
    y(ib(1:n)) = ia(1:n) ;
end
disp(y)
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