How to return random unique values based only on the value in each row for the first colomn?

Kshitij Singh answered . 2025-07-29 23:24:14

Here's another way, with no loops

 

% Example data matrix 
% I modified this a little from your example to have
% multiple occurences of row maximum in the 5th row also, to give better
% illustration
A = [1, 15200, 3, 5, 7; 15200, 15200, 15200, 7,0; 1,1,1,1, 15200; 9200, 1, 9200,1,1];
% get array dimension for later use
numRows = size(A,1);
% Find the row maximums
rowMax = max(A,[],2);
% Mark locations where row maximums occur
isRowMax = A == rowMax;
% Make matrix with random values wherever row maximums occur and zero
% everywhere else
S = isRowMax.*rand(size(A));
% Select random column amongst occurrences of row maximums
% (column where largest element in S occurs is random)
[~,selectedColumn] = max(S,[],2);
% Return row and column indices for location of maximum in each row
sub = [(1:numRows)' selectedColumn]

 

sub = 4×2
     1     2
     2     2
     3     5
     4     1

 

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