nb2lines function

Use vector files for import and export of weights

Use vector files for import and export of weights, storing spatial entity coordinates in the arcs, and the entity indices in the data frame.

nb2lines(nb, wts, coords, proj4string=NULL, as_sf=FALSE)
listw2lines(listw, coords, proj4string=NULL, as_sf=FALSE)
df2sn(df, i="i", i_ID="i_ID", j="j", wt="wt")

Arguments

• nb: a neighbour object of class nb
• wts: list of general weights corresponding to neighbours
• coords: matrix of region point coordinates, a Spatial object (points or polygons), or an sfc object (points or polygons)
• proj4string: default NULL; if coords is a Spatial or sf object, this value will be used, otherwise the value will be converted appropriately
• as_sf: output object in Spatial or sf format, default FALSE, set to TRUE if coords is an sfc object and FALSE if a Spatial object
• 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

Details

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.

Returns

nb2lines and listw2lines return a SpatialLinesDataFrame object or an sf object; the data frame contains 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.

Author(s)

Roger Bivand Roger.Bivand@nhh.no

Note

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

See Also

sn2listw

Examples

columbus <- st_read(system.file("shapes/columbus.gpkg", package="spData")[1], quiet=TRUE)
col.gal.nb <- read.gal(system.file("weights/columbus.gal", package="spData")[1])
res <- listw2lines(nb2listw(col.gal.nb), st_geometry(columbus))
summary(res)
tf <- paste0(tempfile(), ".gpkg")
st_write(res, dsn=tf, driver="GPKG")
inMap <- st_read(tf)
summary(inMap)
diffnb(sn2listw(df2sn(as.data.frame(inMap)))$neighbours, col.gal.nb)
res1 <- listw2lines(nb2listw(col.gal.nb), as(columbus, "Spatial"))
summary(res1)