matchpt {Biobase} | R Documentation

## Finds Nearest Neighbours for Sets of Points given by NxD Coordinates

### Description

Finds nearest neighbours (using Euclidian distance) for sets of points given by coordinates. Can be used to match one dataset agains another or to locate nearest neighbours within a single dataset.

### Usage

        matchpt(x, y = NULL)

### Arguments

`x` | A matrix (or a vector) of coordinates. Rows represent different points in ND space, where N is the number of columns, and thus coordinates. If argument y is not given, match will be performed within x-dataset.
`y` | If given a matrix (or a vector) of the same space (same N), that could however have different number of points. If given this argument is used to match x against it.

### Value

A matrix of 2 columns and n rows, where n is the number of points in argument x. First column - index of the nearest neighbour, second column - distance to the nearest neighbour. If y is given, index corresponds to the index in y-dataset, if only x is given, then in x.

### Author(s)

Oleg Sklyar, osklyar@ebi.ac.uk

### Source

The C code for this routine is available in `src/matchpt.c` of this package.

### References

Oleg Sklyar, EBI 2006

### Examples

        a <- matrix(c(2,2,3,5,1,8,-1,4,5,6), ncol = 2, nrow = 5)
        matchpt(a)
        b <- c(1,2,4,5,6)
        d <- c(5.3, 3.2, 8.9, 1.3, 5.6, -6, 4.45, 3.32)
        matchpt(b, d)
        matchpt(d, b)

[Package Biobase version 1.12.2 Index]