matchpt {Biobase} | R Documentation |
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.
matchpt(x, y = NULL)
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. |
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.
Oleg Sklyar, osklyar@ebi.ac.uk
The C code for this routine is available in src/matchpt.c
of this package.
Oleg Sklyar, EBI 2006
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)