MATLAB: Choose max among elements with same column 1 value, different column 2 value

duplicatesunique

consider a nx2 matrix like:
A = [1  0.7
  2  0.5
  2  0.6
  2  0.3
  3  0.4
  3  0.1
  4  0.7
  5  0.3
  5  0.3]
I want to create mx2 matrix B subset of A where B as the properties:
  1. B(:1) = unique(A(:,1))
  2. If a value in column 1 of A appears more than once, then B will contain the row from A which has greatest value in column 2 of A
so the answer to the given example would be
B = [1  0.7
2  0.6
3  0.4
4  0.7
5  0.3]
I can easily do this with for-loops and stuff, but I was wondering if anyone could come up with an elegant MATLAB one-liner , or perhaps two- or three-liner? 🙂
(It makes my MATLAB skills better to see how the pros do it in one- two- or three-liners)
Thank you!

Best Answer

B(:,2)=accumarray(A(:,1), A(:,2),[],@max );
B(:,1)=(1:size(B,1)).'
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