[R-sig-Geo] Boundaries for kernel density estimation

[Michael Sumner]

Here is the soap package:

http://www.maths.bath.ac.uk/~sw283/simon/software.html



On Fri, Sep 30, 2011 at 9:17 AM, Michael Sumner <mdsumner at gmail.com> wrote:
> The soap-film smoothing of Simon Wood might be of interest:
>
> http://www.maths.bath.ac.uk/~sw283/simon/papers/soap.pdf
>
> I thought this was in the package mgcv, but I cannot find it. I'm sure
> it is available as an R package somewhere.
>
> Cheers, Mike.
>
>
> On Fri, Sep 30, 2011 at 6:44 AM, Rolf Turner <r.turner at auckland.ac.nz> wrote:
>> On 30/09/11 06:30, Jennifer Crees wrote:
>>>
>>> Hi,
>>>
>>>
>>>
>>> I am carrying out kernel estimation on some species point data. However,
>>> the data are on a continental scale (many of the points hug the southern
>>> coastline of Europe) so that the analysis is including marine areas when
>>> the window is constructed around the point themselves. Is it possible to
>>> specify a boundary so that only the sampled terrestrial area will be
>>> included? Or perhaps it would be easier to look at local intensity?
>>
>> If your boundary were all coastal, you could get what you want by
>> setting edge=FALSE in your call to density() --- I *think*!!!
>>
>> However if some parts of your window boundary are coastline and
>> some parts are not, it looks tricky to me.  One idea might be to do
>> one intensity estimate with edge=FALSE, another with edge=TRUE,
>> and then somehow do a weighted average of the two with weights
>> determined by distance from coastline.  Points near the coastline
>> would get a high weight assigned to the edge=FALSE estimate and
>> a low weight to the edge=TRUE estimate.  And vice-versa.
>>
>> Won't be too easy to implement, and it might be a load of dingos'
>> kidneys anyway --- it's just an idea off the top of my head.
>>
>> I've cc-ed this message to Adrian Baddeley who may have a more
>> sound suggestion.  Here's hoping.
>>
>>    cheers,
>>
>>        Rolf Turner
>>
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>
>
>
> --
> Michael Sumner
> Institute for Marine and Antarctic Studies, University of Tasmania
> Hobart, Australia
> e-mail: mdsumner at gmail.com
>



-- 
Michael Sumner
Institute for Marine and Antarctic Studies, University of Tasmania
Hobart, Australia
e-mail: mdsumner at gmail.com