MATLAB: How to find k nearest vectors from a given vector in 3 dimensions

Question

I have a reference vector and I want to find a fixed k nearest neighbors from a matrix ? How can I do it? Is there any direct way?

Answer 1

This is one way:

V = randi(50,  1, 3);                   % Vector
M = randi(50, 15, 3);                   % Matrix
% 
dif = bsxfun(@minus, V, M);             % Subtract Vector from Matrix
D = sqrt(sum(dif.^2,2));                % Euclidean Distance Metric
[Ds,Ix] = sort(D,'ascend');             % Sort Ascending
k = 5;                                  % Number Of Neighbours
KNN = M(Ix(1:k),:);                     % K-th Nearest Neighbours

This simply finds them. If you have the Statistics Toolbox, the pdist2 function is likely more efficient.