listw2sn {spdep} | R Documentation

## Spatial neighbour sparse representation

### Description

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. The `as.spam.listw` method converts a `"listw"` object to a sparse matrix as defined in the spam package, using `listw2sn()`.

### Usage

    listw2sn(listw)
    sn2listw(sn)
    as.spam.listw(listw)

### Arguments

`listw` | a `listw` object from for example `nb2listw`
`sn` | a `spatial.neighbour` object

### 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(s)

Roger Bivand Roger.Bivand@nhh.no

### See Also

`nb2listw`

### Examples

    example(columbus)
    col.listw <- nb2listw(col.gal.nb)
    col.listw$neighbours[[1]]
    col.listw$weights[[1]]
    col.sn <- listw2sn(col.listw)
    str(col.sn)
    col.sp <- as.spam.listw(col.listw)
    str(col.sp)

[Package spdep version 0.4-56 Index]