R: Test Whether A Point Process Model is Multitype

is.multitype.ppm {spatstat.core} | R Documentation

## Test Whether A Point Process Model is Multitype

### Description

Tests whether a fitted point process model involves “marks” attached to the points that classify the points into several types.

### Usage

      ## S3 method for class 'ppm'
    is.multitype(X, ...)

### Arguments

`X` | Fitted point process model (object of class `"ppm"`) usually obtained from `ppm`.
`...` | Ignored.

### Details

“Marks” are observations attached to each point of a point pattern. For example the `longleaf` dataset contains the locations of trees, each tree being marked by its diameter; the `amacrine` dataset gives the locations of cells of two types (on/off) and the type of cell may be regarded as a mark attached to the location of the cell.

The argument `X` is a fitted point process model (an object of class `"ppm"`) typically obtained by fitting a model to point pattern data using `ppm`.

This function returns `TRUE` if the original data (to which the model `X` was fitted) were a multitype point pattern.

Note that this is not the same as testing whether the model involves terms that depend on the marks (i.e. whether the fitted model ignores the marks in the data). Currently we have not implemented a test for this.

If this function returns `TRUE`, the implications are (for example) that any simulation of this model will require simulation of random marks as well as random point locations.

### Value

Logical value, equal to `TRUE` if `X` is a model that was fitted to a multitype point pattern dataset.

### Author(s)

Adrian Baddeley Adrian.Baddeley@curtin.edu.au

and Rolf Turner r.turner@auckland.ac.nz

### See Also

`is.multitype`, `is.multitype.ppp`

### Examples

       X <- lansing
       # Multitype point pattern --- trees marked by species

      fit1 <- ppm(X, ~ marks, Poisson())
      is.multitype(fit1)
      # TRUE

      fit2 <- ppm(X, ~ 1, Poisson())
      is.multitype(fit2)
      # TRUE

      # Unmarked point pattern
      fit3 <- ppm(cells, ~ 1, Poisson())
      is.multitype(fit3)
      # FALSE

[Package spatstat.core version 2.0-0 Index]