ISMorrill: A function to compute Morrill's segregation index

Description

Morrill's segregation index is a development of ISDuncan's index which takes into account the interactions between spatial units(contiguity). The function can be used in two ways: to provide a contiguity matrix or a external geographic information source (spatial object or shape file).

Usage

ISMorrill(x, c = NULL, queen = FALSE, 
spatobj = NULL, folder = NULL, shape = NULL)

Value

a numeric vector containing the Morrill's segregation index value for each group

Arguments

x: - an object of class matrix (or which can be coerced to that class), where each column represents the distribution of a group within spatial units. The number of columns should be greater than 1 (at least 2 groups are required). You should not include a column with total population, because this will be interpreted as a group.
c: - a standard binary contiguity (adjacency) symmetric matrix where each element Cij equals 1 if i-th and j-th spatial units are adjacent, and 0 otherwise.
queen: - a logical parameter difining criteria used for the contiguity matrix computation, TRUE for queen, FALSE (by default) for rook
spatobj: - a spatial object (SpatialPolygonsDataFrame) with geographic information
folder: - a character vector with the folder (directory) name indicating where the shapefile is located on the drive
shape: - a character vector with the name of the shapefile (without the .shp extension) .

References

Morrill B. (1991) On the measure of geographic segregation. Geography research forum, 11, pp. 25-36.

Examples

Run this code

x <- segdata@data[ ,1:2]
contiguity <- contig(segdata)
foldername <- system.file('extdata', package = 'OasisR')
shapename <- 'segdata'

ISMorrill(x, c = contiguity) 

ISMorrill(x, spatobj = segdata)

ISMorrill(x, folder = foldername, shape = shapename)