protViz (version 0.2.06)

findNN_: find index of nearest neighbor

Description

same as findNN but is uses C++ STL std::lower_bound methode. this function is going to replace findNN.

Usage

findNN_(q, vec, check)

Arguments

q

a double vector which can be considered as query objects.

vec

a sorted double vector which can be considered as a data base.

check

boolean enables test if vec is sorted. default is FALSE

Details

please check ?findNN

Examples

# compare ANSI-C binary search with C++ std::lower_bound
    DB<-c(rep(1.0, 3), rep(2.0, 3))
    q<-c(-1, 1.0, 1.01, 1.5, 1.9)
    abs(DB[findNN(q, DB)] - q)
    abs(DB[findNN_(q, DB)] - q)


    DB<-sort(rnorm(100, mean=100, sd=10))
    # should be 0
    unique(DB[findNN_(DB,DB)] - DB)

    q<-rnorm(100, mean=100)

    idx.NN<-findNN_(q,DB)
    hist(DB[findNN_(q,DB)] - q)

    # definition of findNN_ holds
    i<-1:5
    findNN_(3.5, i)

    i<-1:6
    findNN_(3.5, i)