Keywords - Function groups - @ A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Library: spatial
See also: SPKRsurfls SPKRsurfgls SPKRexpcov SPKRgaucov SPKRsphercov SPKRtrmat SPKRprmat SPKRsemat SPKRcorrelogram SPKRmultcontours

Quantlet: SPKRvariogram
Description: Computes spatial (semi-)variograms of spatial data or residuals. Initially, it divides the range of the data into nint bins, and computes the average squared difference for pairs with separation in each bin. It returns results only for bins with 6 or more pairs.

Reference(s):

Link:
Usage: varres = SPKRcorrelogram (krig, nint)
Input:
krig list - (of type "trls" or "trgls") calculated by SPKRsurfls or SPKRsurfgls
nint scalar - number of bins to be used
Output:
res list - consisting of components xpres, ypres, cntres --
xpres n x 1 - vector of the x coordinates of the variogram
ypres n x 1 - vector of the y coordinates of the variogram
cntres n x 1 - vector of the number of pairs averaged per bin

Note:

Example:

; load the spatial statistics library

library ("spatial")

; read a spatial data set

topo = read("topo.dat")

; calculate a polynomial regression surface of order 2

myres = SPKRsurfls (2, topo)

; calculate the correlogram, using 25 bins

varres = SPKRvariogram (myres, 25)

Result:

A list consisting of x and y coordinates of the variogram

and the number of pairs averaged per bin.


Library: spatial
See also: SPKRsurfls SPKRsurfgls SPKRexpcov SPKRgaucov SPKRsphercov SPKRtrmat SPKRprmat SPKRsemat SPKRcorrelogram SPKRmultcontours

Keywords - Function groups - @ A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Author: Juergen Symanzik, 000725
(C) MD*TECH Method and Data Technologies, 21.9.2000