Extract.leverage.ppm: 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, ...)

Arguments

A leverage object (of class "leverage.ppm") computed by leverage.ppm.

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.

Value

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

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 classleverage.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.

Examples

Run this code

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