surveillance: unionSpatialPolygons – R documentation

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unionSpatialPolygons

Compute the Unary Union of "SpatialPolygons"

Description

Union all subpolygons of a "SpatialPolygons" object. This is a wrapper for the polygon clipping engines implemented by packages rgeos, polyclip, or gpclib.

Usage

unionSpatialPolygons(SpP, method = c("rgeos", "polyclip", "gpclib"), ...)

Arguments

`SpP`	an object of class `"SpatialPolygons"`. For the polyclip `method` only, all polygon classes for which an `xylist`-method exists should work as input.
`method`	polygon clipping machinery to use. Default is to simply call `gUnaryUnion` in package rgeos. For `method="polyclip"`, function `polyclip` from package polyclip is used, whereas `method="gpclib"` calls `unionSpatialPolygons` in package maptools (and requires acceptance of gpclib's restricted license via `surveillance.options(gpclib=TRUE)`).
`...`	further arguments passed to the chosen `method`.

Value

an object of class "SpatialPolygons" representing the union of all subpolygons.

Author(s)

Sebastian Meyer

Examples

## Load districts of Germany
load(system.file("shapes", "districtsD.RData", package = "surveillance"))
plot(districtsD, border = "gray")

## Union these districts using either "rgeos" or "polyclip"
if (requireNamespace("rgeos"))  {
    stateD <- unionSpatialPolygons(districtsD, method = "rgeos")
    plot(stateD, add = TRUE, border = 2, lwd = 2)
}
if (requireNamespace("polyclip")) {
    stateD_pc <- unionSpatialPolygons(districtsD, method = "polyclip")
    plot(stateD_pc, add = TRUE, border = 1, lwd = 2, lty = 2)
}

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