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

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naman 2015-5-16

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回答： Walter Roberson 2015-5-16

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?

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Walter Roberson 2015-5-16

When you say "reference vector", do you mean a line defined in N-dimensional space? And you want to find the k points that lie nearest to the line using Euclidean distance? Or does "reference vector" just mean an N-dimensional point and you want to find its k nearest neighbours using a distance measure you have not specified, possibly Euclidean distance?

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Answer 1

Star Strider 2015-5-16

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https://ww2.mathworks.cn/matlabcentral/answers/217005-how-to-find-k-nearest-vectors-from-a-given-vector-in-3-dimensions#answer_179312

编辑：Star Strider 2015-5-16

在 MATLAB Online 中打开

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