OasisR (version 2.0.0)

Pxy: A function to compute the mean proximity between persons of different groups (Pxy)

Description

Mean proximity, Pxy, computes the mean distance between the members of different groups. The function can be used in two ways: to provide a distance matrix or a external geographic information source (spatial object or shape file).

Usage

Pxy(x, d = NULL, fdist = 'e', distin = 'm',  distout = 'm', diagval = '0', 
spatobj = NULL, folder = NULL, shape = NULL)

Arguments

x

- 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.

d

- a matrix of the distances between spatial unit centroids

fdist

- the method used for distance interaction matrix: e' for inverse exponential function (by default) and 'l' for linear.

distin

- input metric conversion, based on bink package and includes conversions from 'm', 'km', 'inch', 'ft', 'yd', 'mi', 'naut_mi', etc.

distout

- output metric conversion, based on bink package and includes conversions to 'm', 'km', 'inch', 'ft', 'yd', 'mi', 'naut_mi', etc.

diagval

- when providing a spatial object or a shape file, the user has the choice of the spatial matrix diagonal definition: diagval = '0' (by default) for an null diagonal and diagval = 'a' to compute the diagonal as 0.6 * square root (spatial units area) (White, 1983)

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 matrix containing Pxy index values for each pair of groups

References

White M. J. (1983) The Measurement of Spatial Segregation. American Journal of Sociology, 88, p. 1008-1019

See Also

Proximity measures: Pxx, Poo, SP

Clustering Indices: ACL, RCL

Examples

x <- segdata@data[ ,1:2]
ar<-area(segdata)
dist <- distance(segdata)
diag(dist)<-sqrt(ar) * 0.6
foldername <- system.file('extdata', package = 'OasisR')
shapename <- 'segdata'

Pxy(x, spatobj = segdata)

Pxy(x, folder = foldername, shape = shapename, fdist = 'l') 

Pxy(x, spatobj = segdata, diagval ='a')

Pxy(x, d = dist, fdist = 'e')