Computational cost of KNNsearch function

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Massimiliano Romana
Massimiliano Romana on 26 Mar 2021
Answered: Gaurav Garg on 30 Mar 2021
I want to know which is the computational cost of the knnsearch algorithm in Matlab.
[~, distX] = knnsearch(X,X,'K',N,'Distance','chebychev'); where N is length of a vector X.

Answers (1)

Gaurav Garg
Gaurav Garg on 30 Mar 2021
Hi,
knnsearch function can be run with many different input arguments. One such argument is 'NSMethod', which describes the search method for the function.
So, knnsearch can be either 'exhaustive' (which computes the result by comparing with each point in the train dataset), or 'kdtree' (which computes the result through a kD-tree, and can take O(log N) in the best case, where N is the number of points in train set).

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