nb2lines: Use vector files for import and export of weights

In r-spatial/spdep: Spatial Dependence: Weighting Schemes, Statistics

Use vector files for import and export of weights

Description

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

Usage

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.

Value

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.

Note

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

Author(s)

Roger Bivand [e-mail]

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)

r-spatial/spdep documentation built on Dec. 3, 2024, 3:27 a.m.