R: Evaluate Expression Involving Components of a Measure

with.msr {spatstat.core} | R Documentation

## Evaluate Expression Involving Components of a Measure

### Description

An expression involving the names of components of a measure is evaluated.

### Usage

    ## S3 method for class 'msr'
    with(data, expr, ...)

### Arguments

`data` | A measure (object of class `"msr"`).
`expr` | An expression to be evaluated.
`...` | Ignored.

### Details

This is a method for the generic function `with` for the class `"msr"`. The argument `data` should be an object of class `"msr"` representing a measure (a function which assigns a value to each subset of two-dimensional space).

This function can be used to extract the components of the measure, or to perform more complicated manipulations of the components.

The argument `expr` should be an un-evaluated expression in the R language. The expression may involve any of the variable names listed below with their corresponding meanings.

`qlocations` | (point pattern) all quadrature locations
`qweights` | (numeric) all quadrature weights
`density` | (numeric) density value at each quadrature point
`discrete` | (numeric) discrete mass at each quadrature point
`continuous` | (numeric) increment of continuous component
`increment` | (numeric) increment of measure
`is.atom` | (logical) whether quadrature point is an atom
`atoms` | (point pattern) locations of atoms
`atommass` | (numeric) massess of atoms

The measure is the sum of discrete and continuous components. The discrete component assigns non-zero mass to several points called atoms. The continuous component has a density which should be integrated over a region to determine the value for that region.

An object of class `"msr"` approximates the continuous component by a sum over quadrature points. The quadrature points are chosen so that they include the atoms of the measure. In the list above, we have `increment = continuous + discrete`, `continuous = density * qweights`, `is.atom = (discrete > 0)`, `atoms = qlocations[is.atom]` and `atommass = discrete[is.atom]`.

### Value

The result of evaluating the expression could be an object of any kind.

### 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

`msr`, `split.msr`, `measureContinuous`, `measurePositive`

### Examples

       X <- rpoispp(function(x,y) { exp(3+3*x) })
       fit <- ppm(X, ~x+y)
       rp <- residuals(fit, type="pearson")

       with(rp, atoms)
       with(rp, qlocations %mark% continuous)

[Package spatstat.core version 2.3-1 Index]