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Analysing spatial point patterns in R - CSIRO

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4.8 Multitype <strong>po<strong>in</strong>t</strong> <strong>patterns</strong> 27<br />

4.8 Multitype <strong>po<strong>in</strong>t</strong> <strong>patterns</strong><br />

A marked <strong>po<strong>in</strong>t</strong> pattern <strong>in</strong> which the marks are a categorical variable is usually called a multitype<br />

<strong>po<strong>in</strong>t</strong> pattern. The ‘types’ are the different values or levels of the mark variable.<br />

Here is the famous Lans<strong>in</strong>g Woods dataset record<strong>in</strong>g the positions of 2251 trees of 6 different<br />

species (hickories, maples, red oaks, white oaks, black oaks and miscellaneous trees).<br />

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

> lans<strong>in</strong>g<br />

marked planar <strong>po<strong>in</strong>t</strong> pattern: 2251 <strong>po<strong>in</strong>t</strong>s<br />

multitype, with levels = blackoak hickory maple misc redoak<br />

w<strong>in</strong>dow: rectangle = [0, 1] x [0, 1] units (one unit = 924 feet)<br />

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

Marked planar <strong>po<strong>in</strong>t</strong> pattern: 2251 <strong>po<strong>in</strong>t</strong>s<br />

Average <strong>in</strong>tensity 2250 <strong>po<strong>in</strong>t</strong>s per square unit (one unit = 924 feet)<br />

*Pattern conta<strong>in</strong>s duplicated <strong>po<strong>in</strong>t</strong>s*<br />

Multitype:<br />

frequency proportion <strong>in</strong>tensity<br />

blackoak 135 0.0600 135<br />

hickory 703 0.3120 703<br />

maple 514 0.2280 514<br />

misc 105 0.0466 105<br />

redoak 346 0.1540 346<br />

whiteoak 448 0.1990 448<br />

W<strong>in</strong>dow: rectangle = [0, 1]x[0, 1]units<br />

W<strong>in</strong>dow area = 1 square unit<br />

Unit of length: 924 feet<br />

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

blackoak hickory maple misc redoak whiteoak<br />

1 2 3 4 5 6<br />

Copyright<strong>CSIRO</strong> 2010

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