corRatio class,
representing a rational quadratic spatial correlation structure. Letting
$d$ denote the range and $n$ denote the nugget
effect, the correlation between two observations a distance
$r$ apart is $(r/d)^2/(1+(r/d)^2)$ when no nugget effect
is present and
$(1-n)(r/d)^2/(1+(r/d)^2)$ when a
nugget effect is assumed. Objects created using this constructor need
to be later initialized using the appropriate Initialize
method.corRatio(value, form, nugget, metric, fixed)nugget is FALSE, value can
have only one element, corresponding to the "range" of the
rational quadratic correlation structure, which must~ S1+...+Sp, or
~ S1+...+Sp | g, specifying spatial covariates S1
through Sp and, optionally, a grouping factor g.
When a grouping factor is presenFALSE."euclidean" for the root sum-of-squares of distances;
"maximum" for the maximum difference; and "manhattanFALSE, in which case
the coefficients are allowed to vary.corRatio, also inheriting from class
corSpatial, representing a rational quadratic spatial correlation
structure.Initialize.corStruct, distsp1 <- corRatio(form = ~ x + y + z)Run the code above in your browser using DataLab