crossdist {spatstat} | R Documentation |
Computes the distances between pairs of points taken from two different point patterns.
crossdist(X, Y, ..., method="C") crossdist.ppp(X, Y, ..., method="C") crossdist.default(X, Y, x2, y2, ..., method="C")
X,Y |
For crossdist.ppp , the arguments X and Y
should be point patterns (objects of class "ppp" ).
For crossdist.default , the arguments X and Y
should be numeric vectors of equal length specifying the location of
the first point pattern.
|
x2,y2 |
For crossdist.default , these
should be numeric vectors of equal length specifying the location of
the second point pattern.
|
... |
Ignored by crossdist.ppp
and crossdist.default .
|
method |
String specifying which method of calculation to use.
Values are "C" and "interpreted" .
|
Given two point patterns, this function computes the Euclidean distance from each point in the first pattern to each point in the second pattern, and returns a matrix containing these distances.
The function crossdist
is generic, with
a method for point patterns (objects of class "ppp"
)
and a default method.
The method for point patterns expects two
point patterns X
and Y
, and returns the matrix
whose [i,j]
entry is the distance from X[i]
to
Y[j]
.
The default method expects X
and Y
to be numeric vectors
of equal length specifying the coordinates of the first point pattern.
The arguments x2
,y2
specify the coordinates of the
second point pattern.
The argument method
is not normally used. It is
retained only for checking the validity of the software.
If method = "interpreted"
then the distances are
computed using interpreted R code only. If method="C"
(the default) then C code is used.
The C code is faster by a factor of 4.
A matrix whose [i,j]
entry is the distance
from the i
-th point in the first pattern
to the j
-th point in the second pattern.
Pavel Grabarnik pavel.grabar@issp.serpukhov.su and Adrian Baddeley adrian@maths.uwa.edu.au http://www.maths.uwa.edu.au/~adrian/
data(cells) d <- crossdist(cells, runifpoint(6)) d <- crossdist(runif(7), runif(7), runif(12), runif(12))