SpatialEpi: create_geo_objects – R documentation

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create_geo_objects

Create geographical objects to be used in Bayesian Cluster Detection Method

Description

This internal function creates the geographical objects needed to run the Bayesian cluster detection method in bayes_cluster. Specifically it creates all single zones based data objects, where single zones are the zones defined by Kulldorff (1997).

Usage

create_geo_objects(max.prop, population, centroids, sp.obj)

Arguments

`max.prop`	maximum proportion of study region's population each single zone can contain
`population`	vector of length `n` of the population of each area
`centroids`	`n x 2` table of the (x,y)-coordinates of the area centroids. The coordinate system must be grid-based
`sp.obj`	object of class SpatialPolygons (See SpatialPolygons-class) representing the study region

Value

`overlap`	list with two elements: `1. presence` which lists for each area all the single zones it is present in and `2. cluster.list` for each single zone its component areas
`cluster.coords`	`n.zones x 2` matrix of the center and radial area of each single zone

Author(s)

Albert Y. Kim

References

Wakefield J. and Kim A.Y. (2013) A Bayesian model for cluster detection. Biostatistics, 14, 752–765.

Examples

data(pennLC)
max.prop <- 0.15
population <- tapply(pennLC$data$population, pennLC$data$county, sum)
centroids <- latlong2grid(pennLC$geo[, 2:3])
sp.obj <- pennLC$spatial.polygon
output <- create_geo_objects(max.prop, population, centroids, sp.obj)

## number of single zones
nrow(output$cluster.coords)

SpatialEpi

Methods and Data for Spatial Epidemiology

v1.2.3

GPL-2

Authors

Cici Chen [ctb], Albert Y. Kim [aut, cre], Michelle Ross [ctb], Jon Wakefield [aut]

Initial release