topo-unary-gMaximumInscribedCircle: Centroid of Geometry

In rgeos: Interface to Geometry Engine - Open Source ('GEOS')

Centroid of Geometry

Description

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Usage

gMaximumInscribedCircle(spgeom, byid=FALSE, id = NULL, tol=.Machine$double.eps^(1/2),
 checkValidity=NULL)

Arguments

spgeom	sp object as defined in package sp
byid	Logical determining if the function should be applied across subgeometries (TRUE) or the entire object (FALSE)
id	Character vector defining id labels for the resulting geometries, if unspecified returned geometries will be labeled based on their parent geometries' labels.
tol	Numerical tolerance value
checkValidity	default FALSE; error meesages from GEOS do not say clearly which object fails if a topology exception is encountered. If this argument is TRUE, gIsValid is run on each in turn in an environment in which object names are available. If objects are invalid, this is reported and those affected are named

Details

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Author(s)

Roger Bivand & Colin Rundel

See Also

gBoundary gConvexHull gEnvelope gPointOnSurface

Examples

if (version_GEOS0() >= "3.9.0") {
x = readWKT(paste("GEOMETRYCOLLECTION(POLYGON((0 0,10 0,10 10,0 10,0 0)),",
 "POLYGON((15 0,25 15,35 0,15 0)))"))

# Maximum inscribed circles of both the square and circle independently
c1 = gMaximumInscribedCircle(x, byid=TRUE) 
c1_sp <- as(c1, "SpatialPoints") # coercion of straight line segments to points
c1_sp1 <- NULL
if ((length(c1_sp) %% 2) == 0) c1_sp1 <- c1_sp[seq(1, length(c1_sp), 2)]
if (!is.null(c1_sp1)) c1_circ <- gBuffer(c1_sp1, byid=TRUE,
 width=gLength(c1, byid=TRUE))
# Maximum inscribed circle of square and circle together, needs gUnaryUnion(), 
# inscribes circle in the component permitting the largest circle
c2 = gMaximumInscribedCircle(gUnaryUnion(x))

opar <- par(mfrow=c(2,1))
plot(x)
plot(c1, col='red', add=TRUE, lwd=2)
if (!is.null(c1_sp1)) plot(c1_circ, border="red", add=TRUE)
plot(x)
plot(c2, col='blue', add=TRUE)
par(opar)
}

rgeos documentation built on July 9, 2023, 3:08 p.m.