geocmeans {geocmeans} | R Documentation |
The geocmeans package implements a modified c-means algorithm more suited to work with spatial data (characterized by spatial autocorrelation). The spatial information is introduced with a spatial weight matrix W (n * n) where wij indicate the strength of the spatial relationship between the observations i and j. It is recommended to use a matrix standardized by row (so that the sum of each row is 1). More specifically, the spatial c-means combine the euclidean distance of each observation in the data matrix X to each center with the euclidean distance of the lagged version of X by W (WX). A parameter alpha controls for the weight of the lagged matrix. If alpha = 0, then the spatial c-means is equal to a classical c-means. If alpha = 1, then the weights given to X and WX are equals. If alpha = 2, then the weight of WX is twice the one of X and so on. An index to measure the spatial consistency of a classification is proposed in this package.