Analysing spatial point patterns in R - CSIRO

196 Exploratory tools for multitype point patterns
array of markconnect functions for amacrine.
off
on
poff, off(r)
0.00 0.05 0.10 0.15 0.20 0.25
poff, on(r)
0.25 0.35 0.45
0.00 0.05 0.10 0.15 0.20 0.25
r (one unit = 662 microns)
0.00 0.05 0.10 0.15 0.20 0.25
r (one unit = 662 microns)
on
pon, off(r)
0.25 0.35 0.45
pon, on(r)
0.00 0.10 0.20 0.30
off
0.00 0.05 0.10 0.15 0.20 0.25
r (one unit = 662 microns)
0.00 0.05 0.10 0.15 0.20 0.25
r (one unit = 662 microns)
31.3.6 Mark equality function
The composite
p(r) = ∑ i
p ii (r)
can be interpreted as the conditional probability, given that there is a point of the process at a
location u and another point of the process at a location v separated by a distance ||u − v|| = r,
that the two points have the same type.
This is sometimes called the mark equality function. It is a special case of a more general
technique of “mark correlation” which we discuss in Section 32.2. To compute the mark equality
function of a multitype point pattern, use markcorr.
> plot(markcorr(amacrine))
markcorr(amacrine)
k mm(r)
0.0 0.2 0.4 0.6 0.8 1.0
iso
trans
theo
0.00 0.05 0.10 0.15 0.20 0.25
r (one unit = 662 microns)
This plot indicates that nearby points tend to have different types.
CopyrightCSIRO 2010