rpoisppOnLines

From spatstat v1.25-1 by Adrian Baddeley

Generate Poisson Point Pattern on Line Segments

Given a line segment pattern, generate a Poisson random point pattern on the line segments.

Keywords: spatial, datagen

Usage

rpoisppOnLines(lambda, L, lmax = NULL, ...)

Arguments

lambda: Intensity of the Poisson process. A single number, a function(x,y), or a pixel image (object of class "im").
L: Line segment pattern (object of class "psp") on which the points should be generated.
lmax: Maximum possible value of lambda if it is a function or a pixel image.
...: Additional arguments passed to lambda if it is a function.

Details

This command generates a Poisson point process on the one-dimensional system of line segments in L. The result is a point pattern consisting of points lying on the line segments in L. The number of random points falling on any given line segment follows a Poisson distribution. The patterns of points on different segments are independent.

The intensity lambda is the expected number of points per unit length of line segment. It may be constant, or it may depend on spatial location.

The argument lambda may be a single number, or a function(x,y), or a pixel image (object of class "im"). In the two latter cases, the rejection method is used.

The rejection method requires knowledge of lmax, the maximum possible value of lambda. If lmax is not given, it will be computed approximately, by sampling many values of lambda.

Value

A point pattern (object of class "ppp") in the same window as L.

Examples

L <- psp(runif(10), runif(10), runif(10), runif(10),  window=owin())
  plot(L, main="")

  # uniform intensity
  Y <- rpoisppOnLines(4, L)
  plot(Y, add=TRUE, pch="+")

  # intensity is a function
  Y <- rpoisppOnLines(function(x,y){ 10 * x^2}, L, 10)
  plot(L, main="")
  plot(Y, add=TRUE, pch="+")

  # intensity is an image
  Z <- as.im(function(x,y){10 * sqrt(x+y)}, unit.square())
  Y <- rpoisppOnLines(Z, L, 10)
  plot(L, main="")
  plot(Y, add=TRUE, pch="+")

Documentation reproduced from package spatstat, version 1.25-1, License: GPL (>= 2)

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