# gTouches

0th

Percentile

##### Geometry Relationships - Touches

Functions for testing if the geometries have at least one boundary point in common, but no interior points

Keywords
spatial
##### Usage
gTouches(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

• Returns TRUE if the intersection of the boundaries of the two geometries is not empty.

gContains gContainsProperly gCovers gCoveredBy gCrosses gDisjoint gEquals gEqualsExact gIntersects gOverlaps gRelate gWithin

• gTouches
• RGEOSTouches
##### Examples
p1 = readWKT("POLYGON((0 0,1 0,1 1,0 1,0 0))")
p2 = readWKT("POLYGON((0 1,0.5 2,1 1,0 1))")
p3 = readWKT("POLYGON((0.5 1,0 2,1 2,0.5 1))")
p4 = readWKT("POLYGON((0.5 0.5,0 1.5,1 1.5,0.5 0.5))")

l0 = readWKT("LINESTRING(0 1,0.5 2,1 1)")

l1 = readWKT("LINESTRING(0 0,2 2)")
l2 = readWKT("LINESTRING(1 1,2 0)")
l3 = readWKT("LINESTRING(0 2,2 0)")

par(mfrow=c(2,3))
title(paste("Touches:",gTouches(p1,p2)))

title(paste("Touches:",gTouches(p1,p3)))

title(paste("Touches:",gTouches(p1,p4)))

title(paste("Touches:",gTouches(p1,l0)))

title(paste("Touches:",gTouches(l1,l2)))

title(paste("Touches:",gTouches(l1,l3)))
Documentation reproduced from package rgeos, version 0.2-20, License: GPL (>= 2)

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