ACE: A function to compute Massey Absolute Centralisation Index (ACE)

Description

The absolute centralization index measures a group spatial distribution compared to the distribution of land area around the city center. The function can be used in two ways: to provide an area vector and a vector containing the distances between spatial units centroids and the central spatial unit or a external geographic information source (spatial object or shape file).

Usage

ACE(x, a = NULL, dc = NULL, center = 1, 
spatobj = NULL, folder = NULL, shape = NULL)

Value

a numeric vector containing asolute centralisation 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.
a: - a numeric vector containing spatial unit areas
dc: - a numeric vector containing the distances between spatial units centroids and the central spatial unit
center: - a numeric value giving the number of the spatial unit that represents the center in the table
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

Massey D. S. and Denton N. A. (1988) The dimensions of residential segregation. Social Forces 67(2), pp. 281-315.

Examples

Run this code

x <- segdata@data[ ,1:2]
ar<-area(segdata)
distc<- distcenter(segdata, center = 28)
foldername <- system.file('extdata', package = 'OasisR')
shapename <- 'segdata'

ACE(x, a = ar, dc=distc) 

ACE(x, spatobj = segdata, center = 28) 

ACE(x, folder = foldername, shape = shapename, center = 28)