dummy.ppm {spatstat} | R Documentation |
Given a fitted point process model, this function extracts the `dummy points' of the quadrature scheme used to fit the model.
dummy.ppm(object)
object |
fitted point process model (an object of class "ppm" ).
|
An object of class "ppm"
represents a point process model
that has been fitted to data. It is typically produced by
the maximum pseudolikelihood fitting algorithm mpl
.
The mpl
algorithm approximates the pseudolikelihood
integral by a sum over a finite set of quadrature points,
which is constructed by augmenting
the original data point pattern by a set of ``dummy'' points.
The fitted model object returned by mpl
contains complete information about this quadrature scheme.
See mpl
or ppm.object
for further
information.
This function extracts the dummy points of the quadrature scheme. A typical use of this function would be to count the number of dummy points, to gauge the accuracy of the approximation to the exact pseudolikelihood.
See ppm.object
for a list of all operations that can be
performed on objects of class "ppm"
.
A point pattern (object of class "ppp"
).
Adrian Baddeley adrian@maths.uwa.edu.au http://www.maths.uwa.edu.au/~adrian/ and Rolf Turner rolf@math.unb.ca http://www.math.unb.ca/~rolf
require(spatstat) data(cells) fit <- mpl(cells, ~1, Strauss(r=0.1), rbord=0.1) X <- dummy.ppm(fit) X$n # this is the number of dummy points in the quadrature scheme