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Analysing spatial point patterns in R - CSIRO

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86 Dependence of <strong>in</strong>tensity on a covariate<br />

A slightly more sophisticated version ofdistmap is the commanddistfun. Whereasdistmap<br />

returns a pixel image at a certa<strong>in</strong> <strong>spatial</strong> resolution, distfun returns a function with arguments<br />

(x,y) that can be evaluated at any <strong>spatial</strong> location.<br />

> f f<br />

Distance function for l<strong>in</strong>e segment pattern<br />

planar l<strong>in</strong>e segment pattern: 90 l<strong>in</strong>e segments<br />

w<strong>in</strong>dow: rectangle = [-158.233, -0.19] x [-0.335, 35] km<br />

> f(-42, 10)<br />

[1] 2.387029<br />

In most commands <strong>in</strong> spatstat where a pixel image is required, a distfun can be used <strong>in</strong> its<br />

place. This <strong>in</strong>creases the precision of many calculations. It is usually advisable to call distfun,<br />

unless you really need a pixel image.<br />

Copyright<strong>CSIRO</strong> 2010

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