Spatial neighbour sparse representation

The function makes a "spatial neighbour" object representation (similar to the S-PLUS spatial statististics module representation of a "listw" spatial weights object. sn2listw() is the inverse function to listw2sn(), creating a "listw" object from a "spatial neighbour" object.

listw2sn(listw)
sn2listw(sn, style = NULL, zero.policy = NULL, from_mat2listw=FALSE)

Arguments

listw

a listw object from for example nb2listw

sn

a spatial.neighbour object

style

default NULL, missing, set to "M" and warning given; if not "M", passed to nb2listw to re-build the object

zero.policy

default NULL, use global option value; if FALSE stop with error for any empty neighbour sets, if TRUE permit the weights list to be formed with zero-length weights vectors

from_mat2listw

default FALSE, set TRUE if called from mat2listw

Value

listw2sn()returns a data frame with three columns, and with class spatial.neighbour:

from

region number id for the start of the link (S-PLUS row.id)

to

region number id for the end of the link (S-PLUS col.id)

weights

weight for this link

Author

Roger Bivand Roger.Bivand@nhh.no

See also

nb2listw

Examples

columbus <- st_read(system.file("shapes/columbus.shp", package="spData")[1], quiet=TRUE)
col.gal.nb <- read.gal(system.file("weights/columbus.gal", package="spData")[1])
col.listw <- nb2listw(col.gal.nb)
col.listw$neighbours[[1]]
#> [1] 2 3
col.listw$weights[[1]]
#> [1] 0.5 0.5
col.sn <- listw2sn(col.listw)
str(col.sn)
#> Classes ‘spatial.neighbour’ and 'data.frame':	230 obs. of  3 variables:
#>  $ from   : int  1 1 2 2 2 3 3 3 3 4 ...
#>  $ to     : int  2 3 1 3 4 1 2 4 5 2 ...
#>  $ weights: num  0.5 0.5 0.333 0.333 0.333 ...
#>  - attr(*, "n")= int 49
#>  - attr(*, "region.id")= chr [1:49] "1" "2" "3" "4" ...
#>  - attr(*, "neighbours.attrs")= chr [1:6] "class" "region.id" "GeoDa" "gal" ...
#>  - attr(*, "weights.attrs")= chr [1:3] "mode" "W" "comp"
#>  - attr(*, "GeoDa")=List of 2
#>   ..$ shpfile: chr NA
#>   ..$ ind    : chr NA
#>  - attr(*, "listw.call")= language nb2listw(neighbours = col.gal.nb)