Envelops for Empirical Variograms Based on Permutation
Computes envelops for empirical variograms by permutation of the data values on the spatial locations.
variog.mc.env(geodata, coords = geodata$coords, data = geodata$data,
obj.variog, nsim = 99, save.sim = FALSE, messages)geodata |
a list containing elements |
coords |
an n x 2 matrix, each row containing Euclidean
coordinates of the n data locations. By default it takes the
element |
data |
a vector with the data values. By default it takes the
element |
obj.variog |
an object of the class |
nsim |
number of simulations used to compute the envelope. Defaults to 99. |
save.sim |
logical. Indicates whether or not the simulated data
are included in the output. Defaults to |
messages |
logical. If |
The envelops are obtained by permutation. For each simulations data values are randomly allocated to the spatial locations. The empirical variogram is computed for each simulation using the same lags as for the variogram originally computed for the data. The envelops are computed by taking, at each lag, the maximum and minimum values of the variograms for the simulated data.
An object of the class "variogram.envelope" which is a
list with the following components:
u |
a vector with distances. |
v.lower |
a vector with the minimum variogram values at each
distance in |
v.upper |
a vector with the maximum variogram values at each
distance in |
simulations |
a matrix with simulated data.
Only returned if |
Paulo Justiniano Ribeiro Jr. paulojus@leg.ufpr.br,
Peter J. Diggle p.diggle@lancaster.ac.uk.
Further information on the package geoR can be found at:
http://www.leg.ufpr.br/geoR.
variog.model.env for envelops computed by
from a model specification,
variog for variogram calculations,
plot.variogram and variog.mc.env for
graphical output.
s100.vario <- variog(s100, max.dist=1) s100.env <- variog.mc.env(s100, obj.var = s100.vario) plot(s100.vario, envelope = s100.env)
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