how to locate rows that has max values in r*2 matrix?

I want to get the max values in a r*2 matrix. r is input from the user. Then, I want to get the complete row(s) where the maxima are. The example here may make it clear:

x = [1 7; 0 5; 9 -1];
n = max(x, [], 1);   % Return the max value of each column
>> n = [9, 7] % The max values for columns 1 and 2

but I want to return the rows of the max values, so I want the result to be:

M=[1 7; 9 -1]

The rows in matrix x change based on input from the user, but the number of columns are fixed to 2.

Answer 1

[James Tursa]

E.g., assuming you always want two rows (which might be the same):

[~,rows] = max(x,[],1);
M = x(sort(rows),:);

If you don't want a row repeated, then simply add code to detect this and return only one row in that case.

[JacobM]

thanks, works perfect

[Satuk Bugrahan]

[~,rows] = max(x,[],1);
    M = x(sort(rows),:);

I think that code wont give you expected answer when you have same max number at different rows . For example for x=[1 7;0 5 ;9 -1 ; 3 7] ,above code will have M=[1 7;9 -1] as an answer. More correct answer must be M=[1 7;9 -1;3 7] . With best wishes;

Answer 2

[Satuk Bugrahan]

      [~,rows] = max(x,[],1);
      M = x(sort(rows),:);

I think that code wont give you expected answer when you have same max number at different rows . Like in my code ;

     x= [1 7 ;0 5 ;9 -1;3 7];
     n=max(x,[],1); 
     inds_1 = find(x(:,1)==n(1)) ;
     [rown_1, coln_1] = ind2sub(size(x),inds_1);
     inds_2 = find(x(:,2)==n(2)) ;
     [rown_2, coln_2] = ind2sub(size(x),inds_2);
     rowns = [rown_1 ;rown_2] ;
     M=zeros(numel(rowns),2) ;
     for a=1:numel(rowns)
        M(a,:)=x(rowns(a),:) ;
     end

The answer for this specified x matrix, M=[9 -1;1 7;3 7] . Since maximum number for second column is '7' and we have two rows with having '7' in their second column.

[JacobM]

Thanks Satuk for your input, I tested the code provided by James and it works for all cases I have, so it returns all the rows with highest values. Thanks again for your help and it is really appreciated