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 centre. 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)

Arguments

- an object of class matrix (or which can be coerced to that class), where each column represents the distribution of a population group, within spatial units. The number of columns should be greater than 1 (at least 2 population groups are required). You should not include a column with total population in each unit, because this will be interpreted as a group.

- a numeric vector containing the areas of spatial units

- 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 centre in the table

spatobj

- a spatial object (SpatialPolygonsDataFrame) containing geographic information

folder

- a character vector with the folder (directory) name indicating where the shapefile with the geographic information is located.

shape

- a character vector with the name of the shapefile (without the .shp extension) which contains the geographic information

Value

a numeric vector containing asolute centralisation index value for each population group

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

# NOT RUN {
x <- segdata@data[ ,1:2]
ar<-area(segdata)
distc<- distcenter(segdata, center = 45)
foldername <- system.file('extdata', package = 'OasisR')
shapename <- 'segdata'

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

ACE(x, spatobj = segdata, center = 45) 

ACE(x, folder = foldername, shape = shapename, center = 45) 

# }