quad.ppm {spatstat}R Documentation

Extract Quadrature Scheme Used to Fit a Point Process Model

Description

Given a fitted point process model, this function extracts the quadrature scheme used to fit the model.

Usage

  quad.ppm(object)

Arguments

object fitted point process model (an object of class "ppm").

Details

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 quadrature scheme. A typical use of this function would be to inspect the quadrature scheme (points and weights) 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". See quad.object for a list of all operations that can be performed on objects of class "quad".

Value

A quadrature scheme (object of class "quad").

Author(s)

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

See Also

ppm.object, quad.object, mpl

Examples

 require(spatstat)
 data(cells)
 fit <- mpl(cells, ~1, Strauss(r=0.1), rbord=0.1)
 Q <- quad.ppm(fit)
 plot(Q)
 Q$data$n
 Q$dummy$n

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