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Guillaume
on 20 May 2015

One possible way is to find the largest values, replace them with a very small value (-Inf) and search for the new largest values:

A=[1 2 3 4 5; 6 7 9 8 10; 11 12 14 13 15] %your example A was a single row

m = max(A, [], 2); %find the max in each row

A(bsxfun(@eq, A, m)) = -Inf; %replace the max(s) by -Inf

m = max(A, [], 2) %find the new max which is the second largest.

Bruno Luong
on 28 Oct 2018

zahra najja: Please read the other ANSWERS bellow, or even better the DOC of MIN

Thomas Koelen
on 20 May 2015

Edited: Thomas Koelen
on 20 May 2015

Edit: seems like I misread second largest...

, should be ;.

A=[1 2 3 4 5; 6 7 9 8 10; 11 12 14 13 15];

[m,i] = max(A,[],2)

gives you:

m =

5

10

15

i =

5

5

5

example:

A=rand(3,5);

[m,i] = max(A,[],2)

gives:

0.8147 0.9134 0.2785 0.9649 0.9572

0.9058 0.6324 0.5469 0.1576 0.4854

0.1270 0.0975 0.9575 0.9706 0.8003

m =

0.9649

0.9058

0.9706

i =

4

1

4

Thomas Koelen
on 20 May 2015

Finding second or third biggest can be done this way:

m=3;n=4;ggg = rand(m,n);

[svals,idx] = sort(ggg(:),'descend'); % sort to vector

svals(2) % second largest value

[II,JJ] = ind2sub([m,n],idx(2)) % position in the matrix

Guillaume
on 20 May 2015

Doesn't this find the second largest element in the matrix, rather than each row?

Secondly, if there are more than one element equal to the max, it still returns the max.

Guillaume
on 20 May 2015

A generic way of finding the nth largest value of each row, if it exists:

function nl = nthlargestrow(m, n)

%m: a 2d matrix to search

%n: an integer

%nl: cell array containing the nth largest value of each row. If a row does not have n different values, the cell is empty

nl = cell(size(m, 1), 1);

u = cellfun(@unique, num2cell(m, 2), 'UniformOutput', false);

hasnelements = cellfun(@numel, u) >= n;

nl(hasnelements) = cellfun(@(row) row(end-n+1), u(hasnelements), 'UniformOutput', false)

end

Thorsten
on 20 May 2015

A=[1 2 3 4 5; 6 7 9 8 10; 11 12 14 13 15];

% remove highest value in each row

sz = size(A);

[~, ind] = max(A, [], 2);

ind = ind + [0; cumsum(repmat(sz(2), [sz(1)-1 1]))];

A = A';

A(ind) = [];

A = reshape(A, [sz(2)-1 sz(1)])';

% find highest value in each row (i.e., second largest of original matrix)

[max2, ind2] = max(A, [], 2);

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