surveillance: poly2adjmat – R documentation

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poly2adjmat

Derive Adjacency Structure of "SpatialPolygons"

Description

Wrapping around functionality of the spdep package, this function computes the symmetric, binary (0/1), adjacency matrix from a "SpatialPolygons" object. It essentially applies nb2mat(poly2nb(SpP, ...), style="B", zero.policy=zero.policy).

Usage

poly2adjmat(SpP, ..., zero.policy = TRUE)

Arguments

`SpP`	an object inheriting from `"SpatialPolygons"`.
`...`	arguments passed to `poly2nb`. Its `snap` argument might be particularly useful to handle maps with sliver polygons.
`zero.policy`	logical indicating if islands are allowed, see `nb2mat`.

Value

a symmetric numeric indicator matrix of size length(SpP)^2 representing polygon adjacencies.

Author(s)

(of this wrapper) Sebastian Meyer

Examples

if (requireNamespace("spdep")) {
    ## generate adjacency matrix for districts of Bayern and Baden-Wuerttemberg
    data("fluBYBW")
    adjmat <- poly2adjmat(fluBYBW@map)

    ## same as already stored in the neighbourhood slot (in different order)
    stopifnot(all.equal(adjmat,
                        neighbourhood(fluBYBW)[rownames(adjmat),colnames(adjmat)]))

    ## a visual check of the district-specific number of neighbours
    plot(fluBYBW@map)
    text(coordinates(fluBYBW@map), labels=rowSums(adjmat==1), font=2, col=2)

    ## the neighbourhood graph can be plotted with spdep
    plot(spdep::mat2listw(adjmat), coordinates(fluBYBW@map))
}

surveillance

Temporal and Spatio-Temporal Modeling and Monitoring of Epidemic Phenomena

v1.19.1

GPL-2

Authors

Michael H<f6>hle [aut, ths] (<https://orcid.org/0000-0002-0423-6702>), Sebastian Meyer [aut, cre] (<https://orcid.org/0000-0002-1791-9449>), Michaela Paul [aut], Leonhard Held [ctb, ths], Howard Burkom [ctb], Thais Correa [ctb], Mathias Hofmann [ctb], Christian Lang [ctb], Juliane Manitz [ctb], Andrea Riebler [ctb], Daniel Saban<e9>s Bov<e9> [ctb], Ma<eb>lle Salmon [ctb], Dirk Schumacher [ctb], Stefan Steiner [ctb], Mikko Virtanen [ctb], Wei Wei [ctb], Valentin Wimmer [ctb], R Core Team [ctb] (A few code segments are modified versions of code from base R)

Initial release

2021-03-30