nndist {spatstat} | R Documentation |
Computes the distance from each point to its nearest neighbour in a point pattern.
nndist(x, y=NULL, method="C")
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 pattern (object of class "ppp" )
or a list with two components x and y ,
or a matrix with two columns.
|
method |
String specifying which method of calculation to use.
Values are "C" and "interpreted" .
|
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.
Numeric vector of the nearest neighbour distances for each point.
An infinite value is returned if there is only one point in the point pattern.
Pavel Grabarnik pavel.grabar@issp.serpukhov.su and Adrian Baddeley adrian@maths.uwa.edu.au http://www.maths.uwa.edu.au/~adrian/
x <- runif(100) y <- runif(100) d <- nndist(x, y) data(cells) d <- nndist(cells)