rgeos (version 0.2-20)

gCrosses: Geometry Relationships - Crosses and Overlaps

Description

Functions for testing whether geometries share some but not all interior points

Usage

gCrosses(spgeom1, spgeom2 = NULL, byid = FALSE)
	gOverlaps(spgeom1, spgeom2 = NULL, byid = FALSE)

Arguments

spgeom1, spgeom2
sp objects as defined in package sp. If spgeom2 is NULL then spgeom1 is compared to itself.
byid
Logical vector determining if the function should be applied across ids (TRUE) or the entire object (FALSE) for spgeom1 and spgeom2

Value

  • gCrosses returns TRUE when the geometries share some but not all interior points, and the dimension of the intersection is less than that of at least one of the geometries.

    gOverlaps returns TRUE when the geometries share some but not all interior points, and the intersection has the same dimension as the geometries themselves.

See Also

gContains gContainsProperly gCovers gCoveredBy gDisjoint gEquals gEqualsExact gIntersects gRelate gTouches gWithin

Examples

Run this code
l1 = readWKT("LINESTRING(0 3,1 1,2 2,3 0)")
	l2 = readWKT("LINESTRING(0 0.5,1 1,2 2,3 2.5)")
	l3 = readWKT("LINESTRING(1 3,1.5 1,2.5 2)")
	
	pt1 = readWKT("MULTIPOINT(1 1,3 0)")
	pt2 = readWKT("MULTIPOINT(1 1,3 0,1 2)")

	p1 = readWKT("POLYGON((0 0,0 2,1 3.5,3 3,4 1,3 0,0 0))")
	p2 = readWKT("POLYGON((2 2,3 4,4 1,4 0,2 2))")
	
	par(mfrow=c(2,3))
	plot(l1,col='blue');plot(pt1,add=TRUE,pch=16)
	title(paste("Crosses:",gCrosses(l1,pt1),
				"Overlaps:",gOverlaps(l1,pt1)))
	
	plot(l1,col='blue');plot(pt2,add=TRUE,pch=16)
	title(paste("Crosses:",gCrosses(l1,pt2),
				"Overlaps:",gOverlaps(l1,pt2)))
				
	plot(l1,col='blue');plot(l2,add=TRUE)
	title(paste("Crosses:",gCrosses(l1,l2),
				"Overlaps:",gOverlaps(l1,l2)))
				
	plot(l1,col='blue');plot(l3,add=TRUE)
	title(paste("Crosses:",gCrosses(l1,l3),
				"Overlaps:",gOverlaps(l1,l3)))
				
	plot(p1,border='blue',col='blue');plot(l1,add=TRUE)
	title(paste("Crosses:",gCrosses(p1,l1),
				"Overlaps:",gOverlaps(p1,l1)))

	plot(p1,border='blue',col='blue');plot(p2,add=TRUE)
	title(paste("Crosses:",gCrosses(p1,p2),
				"Overlaps:",gOverlaps(p1,p2)))

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