spatstat (version 1.4-3)

nndist: Nearest neighbour distances

Description

Computes the distance from each point to its nearest neighbour in a point pattern.

Usage

nndist(x, y=NULL, method="C")

Arguments

x,y

Arguments specifying the $x$ and $y$ coordinates of a set of points. Typically x and y would be numeric vectors of equal length. Alternatively y may be omitted and x may be a point patter

method

String specifying which method of calculation to use. Values are "C" and "interpreted".

Value

• Numeric vector of the nearest neighbour distances for each point.

Warnings

An infinite value is returned if there is only one point in the point pattern.

Details

This function computes the Euclidean distance from each point in a point pattern to its nearest neighbour (the nearest other point of the pattern).

If method = "interpreted" then the distances are computed using interpreted R code only. If method="C" then C code is used. The C code is faster by two to three orders of magnitude and uses much less memory. If there is only one point (if x has length 1), then a nearest neighbour distance of Inf is returned. If there are no points (if x has length zero) a numeric vector of length zero is returned.

See Also

pairdist, Gest

Examples

x <- runif(100)
   y <- runif(100)
   d <- nndist(x, y)
   data(cells)
   d <- nndist(cells)