CALCULATION OF MAXIMUM VALUE IN EVERY ROW

suppose there is a matrix of 3x3 size i want to calculate the maximum value in every row.

 ex: 3 4 5
     6 9 0
     1 2 3 

 the result i should get at the end should be like this

     0 0 1
     0 1 0 
     0 0 1

[EDITED, code formatted, Jan]

[Brahima DRABO]

suppose your matrix is A: result = A==max(A,[],2)

[Stephen23]

@Brahima DRABO: you should put this as an answer too: you would get votes.

Note to others: ignore the accepted answer, it is very poor code.

Answer 1

[Bart]

try this:

suppose the input matrix is A, the output result matrix is B;

max = 0;
k = 0;
l = 0;
for i=1:3
 for j=1:5
   place(i,j) = 0;
 end
end
for i=1:3
 for j=1:3
  if A(i,j)>=max
   max = A(i,j);
   place(i,j) = 1
  end
 end
end
for k=1:3
 for l=1:3
  if place(k,l) = 1
   if place(k,l+1) = 1
    B(k,l) = 0;
   end
   if place[k,l+2) = 1
    B(k,l) = 0;
   else B(k,l) = 1;
   end
   else B(k,l) = 0;
  end
 end
end

[Jan]

Shadowing the built-in function "max" by a variable is a frequent source of porblems and bugs.

The creation of the variable "place" element by element is very inefficient and should be avoided. "place = zeros(3, 5);" is nicer, faster and consumes less memory. Although this is a tiny example here and runtime does not matter, it is a good idea to follow a clean programming style.

Using nested loops to create B element by element is slow also, again due to the missing pre-allocation.

It is not useful to declare k=0 and l=0 at the beginning.

The algorithm wastes a lot of time. Try it with a 1000x1000 array to feel the difference.

Answer 2

[Jonathan Sullivan]

m = [ 3 4 5
      6 9 0
      1 2 3];
mx = max(m,[],2); % EDIT: was max(m,2); Oops
out = bsxfun(@eq,m,mx);

[raj]

thanx mate!!!

Answer 3

[Jan]

[v, sub] = max(a, [], 2);  % [EDITED], was "max(a, 2)"
sa       = size(a);
b        = zeros(sa);
index    = sub2ind(sa, 1:sa(1), sub);
b(index) = 1;

I cannot try it currently and I find the documentation of sub2ind confusing in this point: Perhaps the 2nd and 3rd argument must be swapped: sub2ind(sa, sub, 1:sa(1)).

[raj]

there is an error in your code... in the 1st line

[Jan]

Thanks, raj, fixed.

Answer 4

[raj]

even the imregionalmax function works well