Generalizing the convex hull of a sample: the R package alphahull

This paper presents the r package alphahull which implements the α-convex hull and the α-shape of a finite set of points in the plane. these geometric structures provide an informative overview of the shape and properties of the point set. unlike the convex hull,the α-convex hull and the α-shape are able to reconstruct non-convex sets. this flexibility make them specially useful in set estimation. since the implementation is based on the intimate relation of theses constructs with delaunay triangulations,the r package alphahull also includes functions to compute voronoi and delaunay tesselations. the usefulness of the package is illustrated with two small simulation studies on boundary length estimation.