Library: | spatial |
See also: | SPKRsurfls SPKRsurfgls SPKRexpcov SPKRgaucov SPKRsphercov SPKRtrmat SPKRprmat SPKRcorrelogram SPKRvariogram SPKRmultcontours |
Quantlet: | SPKRsemat | |
Description: | evaluates a Kriging standard error of prediction surface over a grid |
Usage: | res = SPKRsemat (obj, xl, xu, yl, yu, n {, se}) | |
Input: | ||
obj | list, (of type "trgls") calculated by SPKRsurfgls | |
xl | scalar, lower limit in x-direction of the rectangle for grid | |
xu | scalar, upper limit in x-direction of the rectangle for grid | |
yl | scalar, lower limit in y-direction of the rectangle for grid | |
yu | scalar, upper limit in y-direction of the rectangle for grid | |
n | scalar, used to create a n x n grid within the rectangle | |
se | optional scalar, standard error at distance zero as a multiple of the supplied covariance; if omitted, estimated under the assumption that a correlation function has been applied before | |
Output: | ||
res | list, consisting of components z, xl, xu, yl, yu, n and type for further usage with SPKRmultcontours: | |
res.z | (n+1)^2 x 3 matrix, grid | |
xl | scalar, same as input value xl | |
xu | scalar, same as input value xu | |
yl | scalar, same as input value yl | |
yu | scalar, same as input value yu | |
n | scalar, same as input value n | |
type | string, "semat" |
; loads the spatial statistics library library("spatial") ; reads a spatial data set topo = read("topo.dat") ; calculates a trend surface of order 2, using expcov as ; spatial covariance function with dval = 0.7, alph = 0, ; and se = 1 myres = SPKRsurfgls(2, 0, topo, 1000, 0.7, 0, 1) ; calculates a 30 x 30 grid within [0, 6.5] x [0, 6.5] ; using trend surface myres mygrid = SPKRsemat(myres, 0, 6.5, 0, 6.5, 30) mygrid
A grid suitable for display through SPKRmultcontours: Contents of mygrid.z [ 1,] 0 0 31.116 [ 2,] 0.21667 0 28.404 [ 3,] 0.43333 0 26.577 [ 4,] 0.65 0 25.693 [ 5,] 0.86667 0 24.611 ... Contents of mygrid.xl [1,] 0 Contents of mygrid.xu [1,] 6.5 Contents of mygrid.yl [1,] 0 Contents of mygrid.yu [1,] 6.5 Contents of mygrid.n [1,] 30 Contents of mygrid.type [1,] "semat"