corRExpwr2 | R Documentation |
This function is a constructor for the 'corRExpwr2'
class, representing a non-separable spatial correlation structure. Letting rs denote the spatial range, ps the spatial shape, rt the temporal range, pt the temporal shape, and lambda the space-time interaction, the correlation between two observations a distance d apart in space and t in time is exp(-(d/rs)^ps - (t/rt)^pt - lambda * (d/rs)^ps * (t/rt)^pt).
corRExpwr2(value = numeric(0), form = ~ 1, metric = c("euclidean", "maximum", "manhattan", "haversine"), radius = 3956)
value |
optional numeric vector of five parameter values for the powered exponential correlation structure, corresponding to the “spatial range”, “spatial shape”, “temporal range”, “temporal shape”, and “space-time interaction”. The range parameter values must be greater than zero, the shapes in the interval (0, 2], and the interaction greater than or equal to zero. Defaults to |
form |
one-sided formula of the form |
metric |
optional character string specifying the distance metric to be used. The currently available options are |
radius |
radius to be used in the haversine formula for great-circle distance. Defaults to the Earth's radius of 3,956 miles. |
Object of class 'corRExpwr2'
, inheriting from class 'corRSpatioTemporal'
, representing a non-separable spatial correlation structure.
When "haversine"
is used as the distance metric, longitude and latitude coordinates must be given as the first and second covariates, respectively, in the formula specification for the form
argument.
Brian Smith brian-j-smith@uiowa.edu
Cressie, N. and Huang, H.-C. (1993) “Classes of Nonseperable, Spatio-Temporal Stationary Covariance Functions”, Journal of the American Statistical Association, 94, 1330-1340.
Gneiting, T. (2002) “Nonseparable, stationary covariance functions for space-time data”, Journal of the American Statistical Association, 97, 590-600.
corRClasses
sp1 <- corRExpwr2(form = ~ x + y + t) spatDat <- data.frame(x = (0:4)/4, y = (0:4)/4, t=(0:4)/4) cs1Expwr <- corRExpwr2(c(1, 1, 1, 1, 1), form = ~ x + y + t) cs1Expwr <- Initialize(cs1Expwr, spatDat) corMatrix(cs1Expwr) cs2Expwr <- corRExpwr2(c(1, 1, 1, 1, 1), form = ~ x + y + t, metric = "man") cs2Expwr <- Initialize(cs2Expwr, spatDat) corMatrix(cs2Expwr)
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