R: Extract Subset of Leverage Object

Extract.leverage.ppm {spatstat.core} | R Documentation

## Extract Subset of Leverage Object

### Description

Extract a subset of a leverage map, or extract the leverage values at specified locations.

### Usage

      ## S3 method for class 'leverage.ppm'
    x[i, ..., update=TRUE]

### Arguments

`x` | A leverage object (of class `"leverage.ppm"`) computed by `leverage.ppm`.
`i` | Subset index (passed to `[.im`). Either a spatial window (object of class `"owin"`) or a spatial point pattern (object of class `"ppp"`).
`...` | Further arguments passed to `[.im`, especially the argument `drop`.
`update` | Logical value indicating whether to update the internally-stored value of the mean leverage, by averaging over the specified subset.

### Details

An object of class `"leverage.ppm"` contains the values of the leverage function for a point process model, computed by `leverage.ppm`.

This function extracts a designated subset of the leverage values, either as another leverage object, or as a vector of numeric values.

The function `[.leverage.ppm` is a method for `[` for the class `"leverage.ppm"`. The argument `i` should be either

- a spatial window (object of class `"owin"`) determining a region where the leverage map is required. The result will typically be another leverage map (object of class `leverage.ppm`).

- a spatial point pattern (object of class `"ppp"`) specifying locations at which the leverage values are required. The result will be a numeric vector.

The subset operator for images, `[.im`, is applied to the leverage map. If this yields a pixel image, then the result of `[.leverage.ppm` is another leverage object. Otherwise, a vector containing the numeric values of leverage is returned.

### Value

Another object of class `"leverage.ppm"`, or a vector of numeric values of leverage.

### Author(s)

Adrian Baddeley Adrian.Baddeley@curtin.edu.au, Rolf Turner r.turner@auckland.ac.nz and Ege Rubak rubak@math.aau.dk

### See Also

`leverage.ppm`.

### Examples

       fit <- ppm(cells ~x)
       lev <- leverage(fit)
       b <- owin(c(0.1, 0.3), c(0.2, 0.4))
       lev[b]
       lev[cells]

[Package spatstat.core version 2.3-0 Index]