PBSmapping (version 2.72.1)

thinPolys: Thin a PolySet of Polygons

Description

Thin 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 kilometres when proj is "LL" and "UTM"; otherwise, same units as polys).

filter

minimum number of vertices per result polygon.

Value

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

Details

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

See Also

thickenPolys.

Examples

# NOT RUN {
local(envir=.PBSmapEnv,expr={
  oldpar = par(no.readonly=TRUE)
  #--- load the data (if using R)
  if (!is.null(version$language) && (version$language=="R"))
    data(nepacLL,envir=.PBSmapEnv)
  #--- 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)
  par(oldpar)
})
# }