R: Convert to Pixel Image on Linear Network

as.linim {spatstat} | R Documentation

## Convert to Pixel Image on Linear Network

### Description

Converts various kinds of data to a pixel image on a linear network.

### Usage

      as.linim(X, ...)

      ## S3 method for class 'linim'
    as.linim(X, ...)

      ## Default S3 method:
    as.linim(X, L, ...,
                                 eps = NULL, dimyx = NULL, xy = NULL,
                                 delta=NULL)

      ## S3 method for class 'linfun'
    as.linim(X, L=domain(X), ...,
                                eps = NULL, dimyx = NULL, xy = NULL,
                                delta=NULL)

### Arguments

`X` | Data to be converted to a pixel image on a linear network.
`L` | Linear network (object of class `"linnet"`).
`...` | Additional arguments passed to `X` when `X` is a function.
`eps,dimyx,xy` | Optional arguments passed to `as.mask` to control the pixel resolution.
`delta` | Optional. Numeric value giving the approximate distance (in coordinate units) between successive sample points along each segment of the network.

### Details

This function converts the data `X` into a pixel image on a linear network, an object of class `"linim"` (see `linim`).

The argument `X` may be any of the following:

- a function on a linear network, an object of class `"linfun"`.

- a pixel image on a linear network, an object of class `"linim"`.

- a pixel image, an object of class `"im"`.

- any type of data acceptable to `as.im`, such as a function, numeric value, or window.

First `X` is converted to a pixel image object `Y` (object of class `"im"`). The conversion is performed by `as.im`. The arguments `eps`, `dimyx` and `xy` determine the pixel resolution.

Next `Y` is converted to a pixel image on a linear network using `linim`. The argument `L` determines the linear network. If `L` is missing or `NULL`, then `X` should be an object of class `"linim"`, and `L` defaults to the linear network on which `X` is defined.

In addition to converting the function to a pixel image, the algorithm also generates a fine grid of sample points evenly spaced along each segment of the network (with spacing at most `delta` coordinate units). The function values at these sample points are stored in the resulting object as a data frame (the argument `df` of `linim`). This mechanism allows greater accuracy for some calculations (such as `integral.linim`).

### Value

An image object on a linear network; an object of class `"linim"`.

### 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

`as.im`

### Examples

      f <- function(x,y){ x + y }
      plot(as.linim(f, simplenet))

[Package spatstat version 1.54-0 Index]