Barry Rowlingson, Adrian Baddeley, Rolf Turner, Peter Diggle Rasp: A Package for Spatial Statistics ************************************************************ This paper describes the development of a new R package for spatial data and statistics. We review existing packages that deal with spatial information and comment on how they handle the basic data. Our goal is then to construct a unifying spatial data structure that can form a base for any spatial statistics packages. We build on our experience with earlier packages -- spatstat (http://www.maths.uwa.edu.au/~adrian/spatstat.html) and splancs (http://www.maths.lancs.ac.uk/Software/Splancs/) -- to produce a package with extensive data-manipulation and statistical functionality. An object-oriented design is used throughout to abstract functionality from any implementation specifics, but we take care to present the user with simple functions that have sensible defaults. The paper is as much a technical document on package design as it is a story of how such a package evolves from the ideas of the authors. The basic functionality deals with coordinates and associated attributes of each coordinate. The coordinates may be Cartesian spatial locations in up to three dimensions, together with an optional temporal location to handle space-time data. Data structures and methods for polygonal regions are also implemented. Currently we have functions for spatial point-pattern analysis derived from spatstat and splancs. The geostatistical functionality of the geoR package can be easily integrated, as well as other packages currently in the CRAN.