crossdist.ppp {spatstat} | R Documentation |
Computes the distances between pairs of points taken from two different point patterns.
## S3 method for class 'ppp': crossdist(X, Y, ..., periodic=FALSE, method="C")
X,Y |
Point patterns (objects of class "ppp" ).
|
... |
Ignored. |
periodic |
Logical. Specifies whether to apply a periodic edge correction. |
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.
This is a method for the generic function crossdist
for point patterns (objects of class "ppp"
).
This function expects two
point patterns X
and Y
, and returns the matrix
whose [i,j]
entry is the distance from X[i]
to
Y[j]
.
Alternatively if periodic=TRUE
, then provided the windows
containing X
and Y
are identical and are rectangular,
then the distances will be computed in the `periodic'
sense (also known as `torus' distance): opposite edges of the
rectangle are regarded as equivalent.
This is meaningless if the window is not a rectangle.
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 X
to the j
-th point in Y
.
Pavel Grabarnik pavel.grabar@issp.serpukhov.su and Adrian Baddeley adrian@maths.uwa.edu.au http://www.maths.uwa.edu.au/~adrian/
crossdist
,
crossdist.default
,
crossdist.psp
,
pairdist
,
nndist
,
Gest
data(cells) d <- crossdist(cells, runifpoint(6)) d <- crossdist(cells, runifpoint(6), periodic=TRUE)