How can I create a new matrix with x and y coordinates using a for loop?

Lets say I have a matrix A like this:

A=

0 0 1 0 0 0

0 0 0 0 1 0

0 1 0 0 0 1

I want to create a for loop in which this loop creates a new matrix like this

B=

1 3 1

2 5 2

3 2 3

4 6 3

The first column will be the ones showed in the matrix A(point 1,2,3,4) and the second and third columns will be the x and y coordinates of those points(point 1 is at 3 in the x direction and 1 in the y direction). Is it possible?

Answer 1

[Paul]

[y,x]=find(A==1);
num=length(x);
B=[(1:num)',x,y];

If you want to sort the points the way you described do for example this:

[y,x]=find(A==1);
num=length(x);
xy=sortrows([x,y],2)
B=[(1:num)',xy]

[Sebastian]

Is there a way to do it with a for loop?

[Paul]

Yes but why, this is easier. You can do it like this:

p=1;
[row,col] = size(A);
for i = 1:row
    for j=1:col
        if(A(i,j)==1)
            B(p,:)=[p,j,i];
            p=p+1;
        end
    end
end

[Sebastian]

This works perfect for me, Thank you Paul!