[R-sig-Geo] [FORGED] circular spatial polygon

Rolf Turner r.turner at auckland.ac.nz
Tue Sep 12 23:57:43 CEST 2017

On 13/09/17 08:48, Kátia Emidio wrote:

> Dear all,
> My question is how to create a circular spatial polygon, with 8 arcs of 45
> degrees, and radius measuring 15m. Having in the centre point the UTM
> coordinates, zone 20S.
> x= *673593.21*
> y= *673593.21*

"Circular polygon" is a contradiction in terms.  If a shape is a polygon 
then it is *not* a circle.  (Of course in real life we use polygons with 
large numbers of sides to *approximate* circles.  But 8 is not large!)

You can create an octagon with the required centre and radius using 
*spatstat* via:

     oct <- disc(radius=15,centre=c(673593.21,673593.21),npoly=8)

Does that provide (at least a start on) what you want?


Rolf Turner

Technical Editor ANZJS
Department of Statistics
University of Auckland
Phone: +64-9-373-7599 ext.

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