[R] Generating a polygon around points
tsjerkw at gmail.com
Fri Aug 15 17:31:45 CEST 2014
You probably want to have a look at the package alphahull.
On Fri, Aug 15, 2014 at 5:25 PM, Clint Bowman <clint at ecy.wa.gov> wrote:
> Your question seems to need an answer to, "How do you find a convex hull
> on a sphere?" Google has many references.
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> On Fri, 15 Aug 2014, Bob O'Hara wrote:
> I've been struggling for half a day on what should be a simple problem...
>> I have a data frame of lat/long coordinates that describe a region, and I
>> want to draw a polygon around them so I can use that as a boundary (to be
>> thrown at INLA, but those details aren't important). The coordinates are
>> almost on a regular grid: there is some variation in latitude (because
>> we're on a globe).
>> If the coordinates were on a regular grid, I could use as.owin() to create
>> a mask, and go on from there (I have code that will work). But as.owin()
>> doesn't like unevenly spaced points.
>> Can anyone suggest a way to sort this out? Preferable without having to
>> mess around transforming the coordinates.
>> Bob O'Hara
>> Biodiversity and Climate Research Centre
>> Senckenberganlage 25
>> D-60325 Frankfurt am Main,
>> Tel: +49 69 798 40226
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>> and provide commented, minimal, self-contained, reproducible code.
> R-help at r-project.org mailing list
> PLEASE do read the posting guide http://www.R-project.org/
> and provide commented, minimal, self-contained, reproducible code.
Tsjerk A. Wassenaar, Ph.D.
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