With package gdistance, currently under development on R-Forge, it is possible to calculate a number of "non-Euclidean" distances, including the least-cost distance (based on package igraph), resistance distance, and (soon) randomised shortest paths.

Jacob van Etten

--- On Wed, 1/27/10, Pilar Tugores Ferra <Pilar.Tugores@ba.ieo.es> wrote:

From: Pilar Tugores Ferra <Pilar.Tugores@ba.ieo.es>
Subject: Re: [R-sig-Geo] kriging as fish swim, not as crows fly
To: "Martin Renner" <martin.renner@stonebow.otago.ac.nz>
Cc: r-sig-geo@stat.math.ethz.ch
Date: Wednesday, January 27, 2010, 5:35 PM

Hi, Martin
Two years ago there was a similar discussion on the list:
http://markmail.org/message/tw7ulpxbgixieyys


If I understand it properly, your problem is you need to compute your variogram using non-euclidian distances.
As far as I know, there is no package in R that can do so (correct me if I am wrong). 
There is a function LCP_Krige that I think you can find on the net. It is not an R function but a mixture of ArcGis 8.x and Matlab. Maybe you can use it or try to adapt it to R...
Jensen, OP, MC Christman and TJ Mller. 2006. Landscape-based geostatistics: a case study of the distribution of blue crab in Chesapeake Bay. Envirometrics. 17:605-621.
I was interested in applying this sort of analysis but I didn't suceed.
I hope you are more lacky!

Cheers,
Pilar 



Mª Pilar Tugores Ferrà
PhD Student
Instituto Español de Oceanografía
Centro Oceanográfico de Baleares
Muelle de Poniente s/n
07015 Palma de Mallorca
Baleares, España
Telf.: (34) 971 133759


-----Mensaje original-----
De: r-sig-geo-bounces@stat.math.ethz.ch [mailto:r-sig-geo-bounces@stat.math.ethz.ch] En nombre de Michael Sumner
Enviado el: 27 January 2010 10:29
Para: Martin Renner
CC: r-sig-geo@stat.math.ethz.ch
Asunto: Re: [R-sig-Geo] kriging as fish swim, not as crows fly

Not kriging as such, but check out the soap-film smoothing in package mgcv:

http://www.maths.bath.ac.uk/~sw283/simon/papers/soap.pdf


FWIW, there are binning methods with MCMC in the package
tripEstimation that have similar features, but they are particularly
focussed on individual track estimation and probably not easily
applied. Is location uncertainty a big issue for your data? What are
the input locations?

Cheers, Mike.


On Wed, Jan 27, 2010 at 7:06 PM, Martin Renner
<martin.renner@stonebow.otago.ac.nz> wrote:
> Hi All,
>
> I want to kirg fish and seabird densities within an estuary which has several arms. Since neither organisms cross land, the appropriate distances would not be euclidian but over-water (as fish swim). There are several papers, describing this problem and how to deal with it (see below), but I have not found an easily accessible implementation. Is anybody aware of a solution in R?
>
> Best,
> Martin
>
>
>
> @article{Rathbun:1998aa,
>        Author = {Rathbun, Stephen L.},
>        Journal = {Environmetrics},
>        Number = {2},
>        Pages = {109--129},
>        Title = {Spatial modelling in irregularly shaped regions: kriging estuaries},
>        Volume = {9},
>        Year = {1998}}
>
> @article{Little:1997aa,
>        Author = {Little, Laurie S. and Edwards, Don and Porter, Dwayne E.},
>        Journal = {Journal of Experimental Marine Biology and Ecology},
>        Number = {1},
>        Pages = {1--11},
>        Title = {Kriging in estuaries: as the crow flies, or as the fish swims?},
>        Volume = {213},
>        Year = {1997}}
>
>
>
>
> Martin Renner
> US Geological Survey
> Alaska Science Center
>
> _______________________________________________
> R-sig-Geo mailing list
> R-sig-Geo@stat.math.ethz.ch
> https://stat.ethz.ch/mailman/listinfo/r-sig-geo

>

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