# formula.ppm

##### Model Formulae for Gibbs Point Process Models

Extract the trend formula, or the terms in the trend formula, in a fitted Gibbs point process model.

##### Usage

```
## S3 method for class 'ppm':
formula(x, \dots)
## S3 method for class 'ppm':
terms(x, \dots)
```

##### Arguments

- x
- An object of class
`"ppm"`

, representing a fitted point process model. - ...
- Arguments passed to other methods.

##### Details

These functions are methods for the generic commands
`formula`

and
`terms`

for the class `"ppm"`

.

An object of class `"ppm"`

represents a fitted
Poisson or Gibbs point process model.
It is obtained from the model-fitting function `ppm`

.

The method `formula.ppm`

extracts the trend formula from the
fitted model `x`

(the formula originally specified as the
argument `trend`

to `ppm`

).
The method `terms.ppm`

extracts the individual
terms in the trend formula.

##### Value

- See the help files for the corresponding generic functions.

##### See Also

`ppm`

,
`as.owin`

,
`coef.ppm`

,
`extractAIC.ppm`

,
`fitted.ppm`

,
`logLik.ppm`

,
`model.frame.ppm`

,
`model.matrix.ppm`

,
`plot.ppm`

,
`predict.ppm`

,
`residuals.ppm`

,
`simulate.ppm`

,
`summary.ppm`

,
`update.ppm`

,
`vcov.ppm`

.

##### Examples

```
data(cells)
fit <- ppm(cells, ~x)
formula(fit)
terms(fit)
```

*Documentation reproduced from package spatstat, version 1.23-5, License: GPL (>= 2)*