thinPolys {PBSmapping}R Documentation

Thin a PolySet of Polygons

Description

Thins a PolySet, where each unique (PID, SID) describes a polygon.

Usage

thinPolys (polys, tol = 1, filter = 3)

Arguments

polys PolySet to thin.
tol tolerance (in kilometers when proj is "LL" and "UTM"; otherwise, same units as polys).
filter minimum number of vertices per result polygon.

Details

This function executes the Douglas-Peuker line simplification algorithm on each polygon within polys.

Value

PolySet containing the thinned data. The function recalculates the POS values for each polygon.

See Also

thickenPolys.

Examples

#--- load the data (if using R)
if (!is.null(version$language) && (version$language == "R"))
  data(nepacLL)
#--- plot a thinned version of Vancouver Island (3 km tolerance)
plotMap(thinPolys(nepacLL[nepacLL$PID == 33, ], tol = 3))
#--- add the original Vancouver Island in a different line type to
#--- emphasize the difference
addPolys(nepacLL[nepacLL$PID == 33, ], border=2, lty=8, density=0)
[Package PBSmapping version 2.09 Index]