RGEOS Utility Functions {rgeos} | R Documentation |
Utility functions for the RGEOS package
getScale() setScale(scale=100000000) translate(spgeom) checkP4S(p4s) version_GEOS() version_GEOS0()
scale |
Numeric value determining the precision of translated geometries |
spgeom |
sp object as defined in package sp |
p4s |
Either a character string or an object of class |
getScale and setScale are used to get and set the scale option in the rgeos environment. This option is used to determine the precision of coordinates when translating to and from GEOS C objects. Precision is defined as 1 / scale.
translate is a testing function which translates the sp object into a GEOS C object and then back into an sp object and is used extensively in the translation unit tests. In all cases it is expected that spgeom
and translate(spgeom)
should be identical.
checkP4S is a validation function for proj4strings and is used in testing.
version_GEOS returns the full runtime version string, and version_GEOS0 only the GEOS version number.
Roger Bivand & Colin Rundel
readWKT("POINT(1.5 1.5)") # With scale set to 1, the following point will be rounded setScale(1) readWKT("POINT(1.5 1.5)") setScale(10) readWKT("POINT(1.5 1.5)") getScale() # Set scale option back to default setScale() # scale option only affect objects when they are translated through rgeos setScale(1) SpatialPoints(data.frame(x=1.5,y=1.5)) translate( SpatialPoints(data.frame(x=1.5,y=1.5)) ) setScale()