nlme: spatial autocorrelation on a sphere
Thanks, but the problem is quite specific and not addressed on the Spatial Data taskview page. Quite specifically, I would like to know how to edit corSpatial functions to calculate great circle distances. The Bayesian equivalent, georamps in the ramps package, is able to do this, therefore I imagine it must be possible for nlme. Dan
From: David Winsemius [dwinsemius at comcast.net]
Sent: 01 October 2012 08:38
To: Dan Bebber
Cc: r-help at r-project.org
Subject: Re: [R] nlme: spatial autocorrelation on a sphere
Sent: 01 October 2012 08:38
To: Dan Bebber
Cc: r-help at r-project.org
Subject: Re: [R] nlme: spatial autocorrelation on a sphere
On Sep 30, 2012, at 6:48 PM, Dan Bebber wrote: > I have spatial data on a sphere (the Earth) for which I would like to run an gls model assuming that the errors are autcorrelated, i.e. including a corSpatial correlation in the model specification. > > In this case the distance metric should be calculated on the sphere, therefore metric = "euclidean" in (for example) corSpher would be incorrect. > > I would be grateful for help on how to write a new distance metric for the corSpatial function. > I believe there are several ways that distances on a sphere can be calculated in R, for example the "distMeeus" function in the geosphere library. However, I have no idea how to write this into a corSpatial function. > > The aim is to end up with a metric = "sphere" option that calculates great circle distances between points using latitude and longitude. LMCTVTFY: http://cran.r-project.org/web/views/Spatial.html -- David Winsemius, MD Alameda, CA, USA