How to return the row vector containing the highest values from a matrix?

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Lewis
Lewis 2016-11-22
评论： Lewis 2016-11-22
Hi, I can't seem to find a solution to this but it's a pretty simple problem. Say I have a matrix:
M = [10 9 11 7 8;
10 9 8 7 6;
9 6 7 8 5]
What I want to do is to somehow extract the row vector which holds the largest sequence. I have tried the max() function but it just doesn't retain the individual rows. It is important that it returns a specific row vector from M.
The rows won't always necessarily be sequential like this, so I cannot just use the row that sums to the largest value either.
Thanks
  2 个评论
James Tursa
James Tursa 2016-11-22
Please define "largest sequence" for us. What is the exact criteria you want for this? What would be returned for your example above?
Lewis
Lewis 2016-11-22
编辑：Image Analyst 2016-11-22
Ah, the example isn't so good actually, but the largest sequence in that example would be
[10 9 11 7 8]
A better example might be:
M = [13 9 8 7 6;
13 12 11 9 8;
13 11 5 3 2]
Where I would want to return the following vector:
[13 12 11 9 8]
because if we were to sort all elements of each vector, then this one would contain the highest, the second highest, the third highest, etc.

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Image Analyst
Image Analyst 2016-11-22
Try this:
M = [13 9 8 7 6;
13 12 11 9 8;
13 11 5 3 2]
% Find the maxima in each column independently.
columnMaxima = max(M, [], 1)
% Now sort in decending order.
columnMaxima = sort(columnMaxima, 'Descend')
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Image Analyst
Image Analyst 2016-11-22
The second, optional output of max supplies the index from which the max value came from. Use it.

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dpb
dpb 2016-11-22
Sort first by row (already done here in these examples), then by column, retaining the sort index. Then (I think, altho didn't prove concluseively) the row will be minimum of the sum of those indices (fewest permutations to arrange).
>> [~,ix]=sort(M,1);
>> [~,ix]=min(sum(ix,2))
>> M(ix,:)
ans =
13 12 11 9 8
>>

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