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Analysing spatial point patterns in R - CSIRO

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214 Gibbs models for multitype <strong>po<strong>in</strong>t</strong> <strong>patterns</strong><br />

34.3.3 Plott<strong>in</strong>g the fitted <strong>in</strong>teraction<br />

The fitted pairwise <strong>in</strong>teraction <strong>in</strong> a <strong>po<strong>in</strong>t</strong> process model can be plotted us<strong>in</strong>g fit<strong>in</strong>. The value<br />

returned by fit<strong>in</strong> is a function array (class "fasp").<br />

> model plot(fit<strong>in</strong>(model))<br />

Fitted pairwise <strong>in</strong>teractions<br />

off<br />

on<br />

Pairwise <strong>in</strong>teraction<br />

0.0 0.4 0.8<br />

Pairwise <strong>in</strong>teraction<br />

0.0 0.4 0.8<br />

0 20 40 60<br />

Distance<br />

0 20 40 60<br />

Distance<br />

on<br />

Pairwise <strong>in</strong>teraction<br />

0.0 0.4 0.8<br />

Pairwise <strong>in</strong>teraction<br />

0.0 0.4 0.8<br />

off<br />

0 20 40 60<br />

Distance<br />

0 20 40 60<br />

Distance<br />

34.3.4 Simulat<strong>in</strong>g a Gibbs model<br />

A fitted Gibbs <strong>po<strong>in</strong>t</strong> process model can be simulated us<strong>in</strong>g rmh.ppm or simulate.ppm.<br />

> rmh(model, verbose = FALSE)<br />

marked planar <strong>po<strong>in</strong>t</strong> pattern: 139 <strong>po<strong>in</strong>t</strong>s<br />

multitype, with levels = off on<br />

w<strong>in</strong>dow: rectangle = [28.08, 778.08] x [16.2, 1007.02] microns<br />

It’s also possible to simulate any specified Gibbs model us<strong>in</strong>g rmh.default with the model<br />

specified ‘by hand’ us<strong>in</strong>g rmhmodel.default.<br />

Copyright<strong>CSIRO</strong> 2010

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