# with.msr

##### Evaluate Expression Involving Components of a Measure

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

##### Usage

```
# S3 method for 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 |

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.

##### See Also

##### Examples

```
# NOT RUN {
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)
# }
```

*Documentation reproduced from package spatstat, version 1.55-1, License: GPL (>= 2)*