marktable: Tabulate Marks in Neighbourhood of Every Point in a Point Pattern

Description

Visit each point in a multitype point pattern, find the neighbouring points, and compile a frequency table of the marks of these neighbour points.

Usage

marktable(X, R, N, exclude=TRUE, collapse=FALSE)

Value

A contingency table (object of class "table"). If collapse=FALSE, the table has one row for each point in X, and one column for each possible mark value. If collapse=TRUE, the table has one row and one column for each possible mark value.

Arguments

X: A multitype point pattern. An object of class "ppp", "lpp", "pp3" or "ppx", with marks which are a factor.
R: Neighbourhood radius. Incompatible with N.
N: Number of neighbours of each point. Incompatible with R.
exclude: Logical. If exclude=TRUE, the neighbours of a point do not include the point itself. If exclude=FALSE, a point belongs to its own neighbourhood.
collapse: Logical. If collapse=FALSE (the default) the results for each point are returned as separate rows of a table. If collapse=TRUE, the results are aggregated according to the type of point.

Author

Adrian Baddeley Adrian.Baddeley@curtin.edu.au and Rolf Turner rolfturner@posteo.net

Details

This algorithm visits each point in the point pattern X, inspects all the neighbouring points within a radius R of the current point (or the N nearest neighbours of the current point), and compiles a frequency table of the marks attached to the neighbours.

The dataset X must be a multitype point pattern, that is, marks(X) must be a factor.

If collapse=FALSE (the default), the result is a two-dimensional contingency table with one row for each point in the pattern, and one column for each possible mark value. The [i,j] entry in the table gives the number of neighbours of point i that have mark j.

If collapse=TRUE, this contingency table is aggregated according to the type of point, so that the result is a contingency table with one row and one column for each possible mark value. The [i,j] entry in the table gives the number of neighbours of a point with mark i that have mark j.

To perform more complicated calculations on the neighbours of every point, use markstat or applynbd.

Examples

Run this code

  head(marktable(amacrine, 0.1))
  head(marktable(amacrine, 0.1, exclude=FALSE))
  marktable(amacrine, N=1, collapse=TRUE)

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