Using GIS data in R

On 21/11/11 08:01, JeffND wrote:

Hi Rolf,

I have a similar question. I want to test whether a point with certain
coordinates is inside
a state, say Texas. It seems that inside.owin() only works for testing if a
point lies in a
regular region, say a polygon. Since Texas has irregular boundary, how do we
achieve this?
Or there is some alternative way we can use.

Thanks!
Jeff

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View this message in context: http://r.789695.n4.nabble.com/Using-GIS-data-in-R-tp1748266p4089242.html
Sent from the R help mailing list archive at Nabble.com.

It would be nice to have some context ... nabble strikes again.

But to get to your question:  How do you think the boundary of Texas
(irregular as it may be) is specified?  I expect that it is specified as
a polygon!!!  It may be *very* ``poly'' --- i.e. have a large number of
edges --- but it's still a polygon and inside.owin() will still work on it.

Have a look at the data set "nbfires" in the spatstat package.  New
Brunswick has an ``irregular boundary'' too!

Have you *tried* making your specification of Texas into an owin object?
Follow the instructions in the vignette given by:

      vignette("shapefiles")

      cheers,

          Rolf Turner