Message-ID: <1344267963643-4639296.post@n4.nabble.com>
Date: 2012-08-06T15:46:03Z
From: Ally
Subject: Identify points that lie within polygon
In-Reply-To: <11536bdd-6c47-4572-9f45-e033d2f059aa@email.android.com>
Thanks for the suggestion, got exactly what I needed from
library(splancs)
?pip
Alastair
Jeff Newmiller wrote
>
> This is off-topic (not about R), and a quick Web search of "test within
> polygon" yields many results, and adding "R" to the search when using
> Google provides hints about applying the algorithms in R.
> ---------------------------------------------------------------------------
> Jeff Newmiller The ..... ..... Go
> Live...
> DCN:<jdnewmil at .ca> Basics: ##.#. ##.#. Live Go...
> Live: OO#.. Dead: OO#.. Playing
> Research Engineer (Solar/Batteries O.O#. #.O#. with
> /Software/Embedded Controllers) .OO#. .OO#.
> rocks...1k
> ---------------------------------------------------------------------------
> Sent from my phone. Please excuse my brevity.
>
> Ally <a.rushworth at .ac> wrote:
>
>>I have a complex 2D polygon with thousands of vertices, and I'd like to
>>be
>>able to identify points from a large set contained within the polygon,
>>and
>>was wondering if there might be an efficient way of doing this? Any
>>advice
>>would be useful! Here is a small example of what I mean:
>>
>># make polygon
>>v1<-c(0,1,1,2,1,3,6,7)
>>v2<-c(1,3,3,5,6,7,8,9)
>>plot(v1, v2, type = "n" )
>>polygon(v1, v2, lwd = 2, col = "red")
>>
>># plot a set of candidate grid points
>>grid<-seq(0, 10, length.out = 30)
>>pts<-expand.grid(grid, grid)
>>points(pts, pch = 19, col = 1, cex = 1)
>>
>>Many thanks!
>>
>>Alastair
>>
>>
>>
>>
>>--
>>View this message in context:
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>>Sent from the R help mailing list archive at Nabble.com.
>>
>>______________________________________________
>>R-help@ mailing list
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>>PLEASE do read the posting guide
>>http://www.R-project.org/posting-guide.html
>>and provide commented, minimal, self-contained, reproducible code.
>
> ______________________________________________
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> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
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