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.