Convert a polygon dataframe in the format used by ggplot2::geom_polygon to a spatialPolygonDataFrame

Assumes that the dataframe only contains rombuses.

poly2sp(polydf)

Arguments

polydf

A polygon in the format required by geom_polygon: a data.frame with values, x and y positions and id labels

Value

A spatialPolygonsDataFrame object, as used in the package 'sp'