read.gal: Read a GAL lattice file into a neighbours list

In spdep: Spatial Dependence: Weighting Schemes, Statistics and Models

Description

The function read.gal() reads a GAL lattice file into a neighbours list for spatial analysis. It will read old and new style (GeoDa) GAL files. The function read.geoda is a helper file for reading comma separated value data files, calling read.csv().

Usage

read.gal(file, region.id=NULL, override.id=FALSE)
read.geoda(file, row.names=NULL, skip=0)

Arguments

file	name of file with GAL lattice data
region.id	region IDs in specified order to coerse neighbours list order and numbering to that of the region.id
override.id	override any given (or NULL) region.id, collecting region.id numbering and order from the GAL file.
row.names	as in row.names in read.csv(), typically a character string naming the column of the file to be used
skip	skip number of lines, as in read.csv()

Details

Luc Anselin (2003): Spatial Analysis Laboratory, Department of Agricultural and Consumer Economics, University of Illinois, Urbana-Champaign, http://www.csiss.org/gispopsci/workshops/2011/PSU/readings/W15_Anselin2007.pdf; Luc Anselin (2003) GeoDa 0.9 User's Guide, pp. 80–81, Spatial Analysis Laboratory, Department of Agricultural and Consumer Economics, University of Illinois, Urbana-Champaign, https://s3.amazonaws.com/geoda/software/docs/geoda093.pdf; GAL - Geographical Algorithms Library, University of Newcastle

Value

The function read.gal() returns an object of class nb with a list of integer vectors containing neighbour region number ids. The function read.geoda returns a data frame, and issues a warning if the returned object has only one column.

Note

Example data originally downloaded from now dead link: http://sal.agecon.uiuc.edu/weights/zips/us48.zip

Author(s)

Roger Bivand [e-mail]

See Also

summary.nb

Examples

us48.fipsno <- read.geoda(system.file("etc/weights/us48.txt",
 package="spdep")[1])
us48.q <- read.gal(system.file("etc/weights/us48_q.GAL", package="spdep")[1],
 us48.fipsno$Fipsno)
us48.r <- read.gal(system.file("etc/weights/us48_rk.GAL", package="spdep")[1],
 us48.fipsno$Fipsno)
data(state)
if (as.numeric(paste(version$major, version$minor, sep="")) < 19) {
 m50.48 <- match(us48.fipsno$"State.name", state.name)
} else {
 m50.48 <- match(us48.fipsno$"State_name", state.name)
}
plot(us48.q, as.matrix(as.data.frame(state.center))[m50.48,])
plot(diffnb(us48.r, us48.q),
 as.matrix(as.data.frame(state.center))[m50.48,], add=TRUE, col="red")
title(main="Differences between rook and queen criteria imported neighbours lists")

Example output

Loading required package: sp
Loading required package: spData
To access larger datasets in this package, install the spDataLarge
package with: `install.packages('spDataLarge',
repos='https://nowosad.github.io/drat/', type='source')`
Loading required package: sf
Linking to GEOS 3.8.0, GDAL 3.0.4, PROJ 6.3.1

spdep documentation built on Aug. 19, 2017, 3:01 a.m.