R: Recompute Envelopes

envelope.envelope {spatstat} | R Documentation

## Recompute Envelopes

### Description

Given a simulation envelope (object of class `"envelope"`), compute another envelope from the same simulation data using different parameters.

### Usage

    ## S3 method for class 'envelope'
    envelope(Y, fun = NULL, ...,
                                transform=NULL, global=FALSE, VARIANCE=FALSE)

### Arguments

`Y` | A simulation envelope (object of class `"envelope"`).
`fun` | Optional. Summary function to be applied to the simulated point patterns.
`...,transform,global,VARIANCE` | Parameters controlling the type of envelope that is re-computed. See `envelope`.

### Details

This function can be used to re-compute a simulation envelope from previously simulated data, using different parameter settings for the envelope: for example, a different significance level, or a global envelope instead of a pointwise envelope.

The function `envelope` is generic. This is the method for the class `"envelope"`.

The argument `Y` should be a simulation envelope (object of class `"envelope"`) produced by any of the methods for `envelope`. Additionally, `Y` must contain either

- the simulated point patterns that were used to create the original envelope (so `Y` should have been created by calling `envelope` with `savepatterns=TRUE`);

- the summary functions of the simulated point patterns that were used to create the original envelope (so `Y` should have been created by calling `envelope` with `savefuns=TRUE`).

If the argument `fun` is given, it should be a summary function that can be applied to the simulated point patterns that were used to create `Y`. The envelope of the summary function `fun` for these point patterns will be computed using the parameters specified in `...`.

If `fun` is not given, then:

- If `Y` contains the summary functions that were used to compute the original envelope, then the new envelope will be computed from these original summary functions.

- Otherwise, if `Y` contains the simulated point patterns. then the K function `Kest` will be applied to each of these simulated point patterns, and the new envelope will be based on the K functions.

The new envelope will be computed using the parameters specified in `...`.

See `envelope` for a full list of envelope parameters. Frequently-used parameters include `nrank` and `nsim` (to change the number of simulations used and the significance level of the envelope), `global` (to change from pointwise to global envelopes) and `VARIANCE` (to compute the envelopes from the sample moments instead of the ranks).

### Value

An envelope (object of class `"envelope"`.

### Author(s)

Adrian Baddeley Adrian.Baddeley@curtin.edu.au

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

### See Also

`envelope`

### Examples

      E <- envelope(cells, Kest, nsim=19, savefuns=TRUE, savepatterns=TRUE)
      E2 <- envelope(E, nrank=2)
      Eg <- envelope(E, global=TRUE)
      EG <- envelope(E, Gest)
      EL <- envelope(E, transform=expression(sqrt(./pi)))

[Package spatstat version 1.63-3 Index]