Find closest coordinates to a point from a list of coordinates where the list also contains that point

I need to find closest point to A=[X2,Y2] among ListofNodes=[X1,Y1; X2,Y2; X3,Y3; ...], and I need to draw a line joining A and the closest point. I am using the following code:

        A = [X2,Y2];
        %compute Euclidean distances:
        distances = sqrt(sum(bsxfun(@minus, ListofNodes , A).^2,2));
        %find the smallest distance and use that as an index into ListofNodes:
        closest = ListofNodes(distances==min(distances),:);
        %draw a line joining the point and the closest coordinates
        h = line(A,closest);
        set(h, 'LineWidth', 0.01, 'Color','blue');

The problem is that ListofNodes also contains A. So, I am getting closest = A. How to solve this problem?

[Aarti Dwivedi]

You can pass ListOfNodes[ListOfNodes ~= A] to your function.

[Rik]

If you are not going to use KSSV's suggestion, you should use sort and use the second element. That would also solve the possibility of ties if there happen to be any.

[KSSV]

If you don't want to use in built finction...get the distance of the point from each point, sort the distances and pick the least distant point. :) . knnsearch also does the same.

Answer 1

[KSSV]

Have a look on knnsearch. It will give you what you want.

A = rand(10,2) ;

idx = knnsearch(A,A(2,:),'k',2) ;  % get two close points 

idx(1) = [] ;  % remove the pomnt itself 

plot(A(:,1),A(:,2),'.r') ;
hold on
plot(A(2,1),A(2,2),'Ob') ;
plot([A(2,1), A(idx,1)],[A(2,2), A(idx,2)])