# simulate.ppm

##### Simulate a Fitted Gibbs Point Process Model

Generates simulated realisations from a fitted Gibbs or Poisson point process model.

##### Usage

```
# S3 method for ppm
simulate(object, nsim=1, ...,
singlerun = FALSE,
start = NULL,
control = default.rmhcontrol(object, w=w),
w = NULL,
project=TRUE, new.coef=NULL,
verbose=FALSE, progress=(nsim > 1),
drop=FALSE)
```

##### Arguments

- object
Fitted point process model. An object of class

`"ppm"`

.- nsim
Number of simulated realisations.

- singlerun
Logical. Whether to generate the simulated realisations from a single long run of the Metropolis-Hastings algorithm (

`singlerun=TRUE`

) or from separate, independent runs of the algorithm (`singlerun=FALSE`

, the default).- start
Data determining the initial state of the Metropolis-Hastings algorithm. See

`rmhstart`

for description of these arguments. Defaults to`list(n.start=npoints(data.ppm(object)))`

meaning that the initial state of the algorithm has the same number of points as the original dataset.- control
Data controlling the running of the Metropolis-Hastings algorithm. See

`rmhcontrol`

for description of these arguments.- w
Optional. The window in which the model is defined. An object of class

`"owin"`

.- …
Further arguments passed to

`rmhcontrol`

, or to`rmh.default`

, or to covariate functions in the model.- project
Logical flag indicating what to do if the fitted model is invalid (in the sense that the values of the fitted coefficients do not specify a valid point process). If

`project=TRUE`

the closest valid model will be simulated; if`project=FALSE`

an error will occur.- verbose
Logical flag indicating whether to print progress reports from

`rmh.ppm`

during the simulation of each point pattern.- progress
Logical flag indicating whether to print progress reports for the sequence of simulations.

- new.coef
New values for the canonical parameters of the model. A numeric vector of the same length as

`coef(object)`

.- drop
Logical. If

`nsim=1`

and`drop=TRUE`

, the result will be a point pattern, rather than a list containing a point pattern.

##### Details

This function is a method for the generic function
`simulate`

for the class `"ppm"`

of fitted
point process models.

Simulations are performed by `rmh.ppm`

.

If `singlerun=FALSE`

(the default), the simulated patterns are
the results of independent runs of the Metropolis-Hastings
algorithm. If `singlerun=TRUE`

, a single long run of the
algorithm is performed, and the state of the simulation is saved
every `nsave`

iterations to yield the simulated patterns.

In the case of a single run, the behaviour is controlled
by the parameters `nsave,nburn,nrep`

. These
are described in `rmhcontrol`

. They may be passed
in the `…`

arguments or included in `control`

.
It is sufficient to specify two
of the three parameters `nsave,nburn,nrep`

.

##### Value

A list of length `nsim`

containing simulated point patterns
(objects of class `"ppp"`

).
It also belongs to the class `"solist"`

, so that it can be
plotted, and the class `"timed"`

, so that the total computation
time is recorded.

##### See Also

##### Examples

```
# NOT RUN {
# }
# NOT RUN {
fit <- ppm(japanesepines, ~1, Strauss(0.1))
simulate(fit, 2)
simulate(fit, 2, singlerun=TRUE, nsave=1e4, nburn=1e4)
# }
```

*Documentation reproduced from package spatstat, version 1.55-1, License: GPL (>= 2)*