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Analysing spatial point patterns in R - CSIRO

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200 Exploratory tools for marked <strong>po<strong>in</strong>t</strong> <strong>patterns</strong><br />

31.5 Adjust<strong>in</strong>g for <strong>in</strong>homogeneity<br />

Inhomogeneous versions of the multitype K function, L function and pair correlation function<br />

also exist.<br />

The command names areKdot.<strong>in</strong>hom,Kcross.<strong>in</strong>hom,Ldot.<strong>in</strong>hom,Lcross.<strong>in</strong>hom,pcfdot.<strong>in</strong>hom<br />

and pcfcross.<strong>in</strong>hom. They require separate estimates of the <strong>in</strong>tensities of the first and second<br />

types of <strong>po<strong>in</strong>t</strong>s. Aga<strong>in</strong> these <strong>in</strong>tensities can be estimated by kernel smooth<strong>in</strong>g.<br />

> data(lans<strong>in</strong>g)<br />

> plot(Kcross.<strong>in</strong>hom(lans<strong>in</strong>g, "whiteoak", "maple", sigma = 0.15))<br />

Kcross.<strong>in</strong>hom(lans<strong>in</strong>g, "whiteoak", "maple", sigma = 0.15)<br />

K<strong>in</strong>hom whiteoak, maple(r)<br />

0.00 0.05 0.10 0.15 0.20<br />

iso<br />

trans<br />

border<br />

theo<br />

0.00 0.05 0.10 0.15 0.20 0.25<br />

r (one unit = 924 feet)<br />

32 Exploratory tools for marked <strong>po<strong>in</strong>t</strong> <strong>patterns</strong><br />

32.1 Numeric marks: distribution and trend<br />

For a <strong>po<strong>in</strong>t</strong> pattern with marks that are numeric (real numbers or <strong>in</strong>tegers) or logical values,<br />

the mark values can be extracted us<strong>in</strong>g the marks function and <strong>in</strong>spected us<strong>in</strong>g the histogram<br />

or kernel density estimate:<br />

> data(longleaf)<br />

> hist(marks(longleaf))<br />

Histogram of marks(longleaf)<br />

Frequency<br />

0 20 40 60 80<br />

0 20 40 60 80<br />

marks(longleaf)<br />

Copyright<strong>CSIRO</strong> 2010

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