nb2lines: Use arc-type shapefiles for import and export of weights
In spdep: Spatial Dependence: Weighting Schemes, Statistics and Models

Description Usage Arguments Details Value Note Author(s) See Also Examples

Use arc-type shapefiles for import and export of weights, storing spatial entity coordinates in the arcs, and the entity indices in the data frame.

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nb2lines(nb, wts, coords, proj4string=CRS(as.character(NA)))
listw2lines(listw, coords, proj4string=CRS(as.character(NA)))
df2sn(df, i="i", i_ID="i_ID", j="j", wt="wt")

`nb`	a neighbour object of class `nb`
`wts`	list of general weights corresponding to neighbours
`coords`	matrix of region point coordinates
`proj4string`	Object of class CRS; holding a valid proj4 string
`listw`	a `listw` object of spatial weights
`df`	a data frame read from a shapefile, derived from the output of `nb2lines`
`i`	character name of column in df with from entity index
`i_ID`	character name of column in df with from entity region ID
`j`	character name of column in df with to entity index
`wt`	character name of column in df with weights

The maptools package function writeSpatialShape is used to transport out the list of lines made by nb2lines or listw2lines, which is a simple wrapper function. The neighbour and weights objects may be retrieved by converting the specified columns of the data slot of the SpatialLinesDataFrame object into a spatial.neighbour object, which is then converted into a weights list object.

nb2lines and listw2lines return a SpatialLinesDataFrame object; its data slot contains a data frame with the from and to indices of the neighbour links and their weights. df2sn converts the data retrieved from reading the data from df back into a spatial.neighbour object.

Original idea due to Gidske Leknes Andersen, Department of Biology, University of Bergen, Norway

Roger Bivand Roger.Bivand@nhh.no

sn2listw, readShapeLines

require(maptools)
example(columbus)
coords <- coordinates(columbus)
res <- listw2lines(nb2listw(col.gal.nb), coords)
summary(res)
fn <- paste(tempdir(), "nbshape", sep="/")
writeLinesShape(res, fn=fn)
inMap <- readShapeLines(fn)
summary(inMap)
diffnb(sn2listw(df2sn(as(inMap, "data.frame")))$neighbours, col.gal.nb)