# gIntersects

0th

Percentile

##### Geometry Relationships - Intersects and Disjoint

Function for testing if the geometries have at least one point in common or no points in common

Keywords
spatial
##### Usage
gIntersects(spgeom1, spgeom2 = NULL, byid = FALSE, prepared=TRUE, returnDense=TRUE)
gDisjoint(spgeom1, spgeom2 = NULL, byid = FALSE, returnDense=TRUE)
##### 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
prepared
Logical determining if prepared geometry (spatially indexed) version of the GEOS function should be used. In general prepared geometries should be faster than the alternative.
returnDense
default TRUE, if false returns a list of the length of spgeom1 of integer vectors listing the 1:length(spgeom2) indices which would be TRUE in the dense logical matrix representation; useful when the sizes of the byid=TRUE returned matrix is
##### Value

• gIntersects returns TRUE if spgeom1 and spgeom2 have at least one point in common.

gDisjoint returns TRUE if spgeom1 and spgeom2 have no points in common.

gContains gContainsProperly gCovers gCoveredBy gCrosses gEquals gEqualsExact gOverlaps gRelate gTouches gWithin

##### Aliases
• gIntersects
• RGEOSIntersects
• gDisjoint
• RGEOSDisjoint
##### Examples
p1 = readWKT("POLYGON((0 0,1 0,1 1,0 1,0 0))")
p2 = readWKT("POLYGON((0.5 1,0 2,1 2,0.5 1))")
p3 = readWKT("POLYGON((0.5 0.5,0 1.5,1 1.5,0.5 0.5))")

l1 = readWKT("LINESTRING(0 3,1 1,2 2,3 0)")
l2 = readWKT("LINESTRING(1 3.5,3 3,2 1)")
l3 = readWKT("LINESTRING(-0.1 0,-0.1 1.1,1 1.1)")

pt1 = readWKT("MULTIPOINT(1 1,3 0,2 1)")
pt2 = readWKT("MULTIPOINT(0 3,3 0,2 1)")
pt3 = readWKT("MULTIPOINT(-0.2 0,1 -0.2,1.2 1,0 1.2)")

par(mfrow=c(3,2))
title(paste("Intersects:",gIntersects(p1,p2),
"Disjoint:",gDisjoint(p1,p2)))

title(paste("Intersects:",gIntersects(p1,p3),
"Disjoint:",gDisjoint(p1,p3)))

title(paste("Intersects:",gIntersects(l1,pt1),
"Disjoint:",gDisjoint(l1,pt1)))

title(paste("Intersects:",gIntersects(l1,pt2),
"Disjoint:",gDisjoint(l1,pt2)))

plot(p1,col='blue',border='blue',xlim=c(-0.5,2),ylim=c(0,2.5))
"Disjoint:",gDisjoint(p1,pt3)))