k Nearest Neighbor Distances

Description

Fast k-nearest neighbor distance searching algorithms.

Usage

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  knn.dist(data, k=10, algorithm=c("kd_tree", "cover_tree", "CR", "brute"))
  knnx.dist(data, query, k=10, algorithm=c("kd_tree", "cover_tree", "CR", "brute"))

Arguments

data

an input data matrix.

query

a query data matrix.

algorithm

nearest neighbor searching algorithm.

k

the maximum number of nearest neighbors to search. The default value is set to 10.

Value

return the Euclidiean distances of k nearest neighbors.

Author(s)

Shengqiao Li. To report any bugs or suggestions please email: shli@stat.wvu.edu.

References

Bentley J.L. (1975), “Multidimensional binary search trees used for associative search,” Communication ACM, 18, 309-517.

Arya S. and Mount D.M. (1993), “Approximate nearest neighbor searching,” Proc. 4th Ann. ACM-SIAM Symposium on Discrete Algorithms (SODA'93), 271-280.

Arya S., Mount D.M., Netanyahu N.S., Silverman R. and Wu A.Y. (1998), “An optimal algorithm for approximate nearest neighbor searching,” Journal of the ACM, 45, 891-923.

Beygelzimer A., Kakade S. and Langford J. (2006), “Cover trees for nearest neighbor,” ACM Proc. 23rd international conference on Machine learning, 148, 97-104.

See Also

get.knn and knn.index .

Examples

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  if(require(mvtnorm))
  {
    sigma<- function(v, r, p)
    {
      	V<- matrix(r^2, ncol=p, nrow=p)
    	  diag(V)<- 1
        V*v
    }

    X<- rmvnorm(1000, mean=rep(0, 20), sigma(1, .5, 20))
    print(system.time(knn.dist(X)) )
    print(system.time(knn.dist(X, algorithm = "kd_tree")))

  }