Class of Fitted Point Process Models
A class ppm
to represent a fitted stochastic model
for a point process. The output of ppm
.
An object of class ppm
represents a stochastic point process
model that has been fitted to a point pattern dataset.
Typically it is the output of the model fitter,
ppm
.
The class ppm
has methods for the following
standard generic functions:
generic | method | description |
print |
print.ppm
|
print details |
plot |
plot.ppm
|
plot fitted model |
predict |
predict.ppm
|
fitted intensity and conditional intensity |
fitted |
fitted.ppm
|
fitted intensity |
coef |
coef.ppm
|
fitted coefficients of model |
anova |
anova.ppm
|
Analysis of Deviance |
formula |
formula.ppm
|
Extract model formula |
terms |
terms.ppm
|
Terms in the model formula |
labels |
labels.ppm
|
Names of estimable terms in the model formula |
residuals |
residuals.ppm
|
Point process residuals |
simulate |
simulate.ppm
|
Simulate the fitted model |
update |
update.ppm
|
Change or refit the model |
vcov |
vcov.ppm
|
Variance/covariance matrix of parameter estimates |
model.frame |
model.frame.ppm
|
Model frame |
model.matrix |
model.matrix.ppm
|
Design matrix |
logLik |
logLik.ppm
|
log pseudo likelihood |
extractAIC |
extractAIC.ppm
|
pseudolikelihood counterpart of AIC |
nobs |
nobs.ppm
|
number of observations |
Objects of class ppm
can also be handled by the
following standard functions, without requiring a special method:
The class ppm
also has methods for the following
generic functions defined in the spatstat package:
generic | method | description |
as.interact |
as.interact.ppm
|
Interpoint interaction structure |
as.owin |
as.owin.ppm
|
Observation window of data |
berman.test |
berman.test.ppm
|
Berman's test |
envelope |
envelope.ppm
|
Simulation envelopes |
fitin |
fitin.ppm
|
Fitted interaction |
is.marked |
is.marked.ppm
|
Determine whether the model is marked |
is.multitype |
is.multitype.ppm
|
Determine whether the model is multitype |
is.poisson |
is.poisson.ppm
|
Determine whether the model is Poisson |
is.stationary |
is.stationary.ppm
|
Determine whether the model is stationary |
cdf.test |
cdf.test.ppm
|
Spatial distribution test |
quadrat.test |
quadrat.test.ppm
|
Quadrat counting test |
reach |
reach.ppm
|
Interaction range of model |
rmhmodel |
rmhmodel.ppm
|
Model in a form that can be simulated |
rmh |
rmh.ppm
|
Perform simulation |
unitname |
unitname.ppm
|
Name of unit of length |
If you really need to get at the internals,
a ppm
object contains at least the following entries:
coef |
the fitted regular parameters (as returned by
glm ) |
trend |
the trend formula or NULL |
interaction |
the point process interaction family
(an object of class "interact" )
or NULL |
Q |
the quadrature scheme used |
maxlogpl |
the maximised value of log pseudolikelihood |
correction |
name of edge correction method used |
See ppm
for explanation of these concepts.
The irregular parameters (e.g. the interaction radius of the
Strauss process) are encoded in the interaction
entry.
However see the Warnings.
The internal representation of ppm
objects
may change slightly between releases of the spatstat package.
Adrian Baddeley Adrian.Baddeley@curtin.edu.au
and Rolf Turner r.turner@auckland.ac.nz
fit <- ppm(cells ~ x, Strauss(0.1), correction="periodic") fit coef(fit) # pred <- predict(fit) pred <- predict(fit, ngrid=20, type="trend") if(interactive()) { plot(fit) }
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