ISAR: Individual Special Area Relationship
In antiphon/sseg: Compute various multitype-summaries for multitype point patterns

Description Usage Arguments Details See Also Examples

Estimate the ISAR statistic for a multitype point pattern.

1	ISAR(x, i, r, intensity, CSR = FALSE)

`x`	Multitype point pattern
`i`	Target species
`r`	r vector
`intensity`	Optional vector of intensities, see details.
`CSR`	Include CSR? Only for homogeneous case.

This function computes the ISAR function. The default action is to compute the homogeneous version, that assumes all component patterns are homogeneous (intensity is constant).

For inhomogeneous computation the intensity can be given. It should be a vector giving the type-wise intensity at each point, or a list of im-objects giving the intensity fields per mark. See density.ppp how to compute the density for indivial patterns, or intensity_multi for a handy wrapper for generating the vector.

Note that CSR is not usually a good hypothesis: It assumes each marginal type is homogeneous Poisson in addition to type-to-type independence.

intensity_optimal

data(lansing, package = "spatstat.data")
# inhomogeneous
i1 <- ISAR(lansing, i = "hickory")
l <- intensity_optimal(lansing)
i2 <- ISAR(lansing, i = "hickory", intensity = l$intensity)
plot(i1)
lines(i2, col=2)