R: Methods for Intensity Functions of Spatial Covariate

methods.rhohat {spatstat.core} | R Documentation

## Methods for Intensity Functions of Spatial Covariate

### Description

These are methods for the class `"rhohat"`.

### Usage

    ## S3 method for class 'rhohat'
    print(x, ...)

    ## S3 method for class 'rhohat'
    plot(x, ..., do.rug=TRUE)

    ## S3 method for class 'rhohat'
    predict(object, ..., relative=FALSE,
                 what=c("rho", "lo", "hi", "se"))

    ## S3 method for class 'rhohat'
    simulate(object, nsim=1, ..., drop=TRUE)

### Arguments

`x,object` | An object of class `"rhohat"` representing a smoothed estimate of the intensity function of a point process.
`...` | Arguments passed to other methods.
`do.rug` | Logical value indicating whether to plot the observed values of the covariate as a rug plot along the horizontal axis.
`relative` | Logical value indicating whether to compute the estimated point process intensity (`relative=FALSE`) or the relative risk (`relative=TRUE`) in the case of a relative risk estimate.
`nsim` | Number of simulations to be generated.
`drop` | Logical value indicating what to do when `nsim=1`. If `drop=TRUE` (the default), a point pattern is returned. If `drop=FALSE`, a list of length 1 containing a point pattern is returned.
`what` | Optional character string (partially matched) specifying which value should be calculated: either the function estimate (`what="rho"`, the default), the lower or upper end of the confidence interval (`what="lo"` or `what="hi"`) or the standard error (`what="se"`).

### Details

These functions are methods for the generic commands `print`, `plot`, `predict` and `simulate` for the class `"rhohat"`.

An object of class `"rhohat"` is an estimate of the intensity of a point process, as a function of a given spatial covariate. See `rhohat`.

The method `plot.rhohat` displays the estimated function rho using `plot.fv`, and optionally adds a `rug` plot of the observed values of the covariate.

The method `predict.rhohat` computes a pixel image of the intensity rho(Z(u)) at each spatial location u, where Z is the spatial covariate.

The method `simulate.rhohat` invokes `predict.rhohat` to determine the predicted intensity, and then simulates a Poisson point process with this intensity.

### Value

For `predict.rhohat` the value is a pixel image (object of class `"im"` or `"linim"`). For `simulate.rhohat` the value is a point pattern (object of class `"ppp"` or `"lpp"`). For other functions, the value is `NULL`.

### Author(s)

Adrian Baddeley Adrian.Baddeley@curtin.edu.au

### See Also

`rhohat`

### Examples

      X <-  rpoispp(function(x,y){exp(3+3*x)})
      rho <- rhohat(X, function(x,y){x})
      rho
      plot(rho)
      Y <- predict(rho)
      plot(Y)
      plot(simulate(rho), add=TRUE)
      #
      fit <- ppm(X, ~x)
      rho <- rhohat(fit, "y")
      opa <- par(mfrow=c(1,2))
      plot(predict(rho))
      plot(predict(rho, relative=TRUE))
      par(opa)
      plot(predict(rho, what="se"))

[Package spatstat.core version 2.4-4 Index]