[R] [R-pkgs] New CRAN package sp: classes and methods for spatial data

From: Edzer J. Pebesma <e.pebesma_at_geog.uu.nl>
Date: Sat 18 Jun 2005 - 00:20:15 EST


We're happy to announce the CRAN release of "sp", an R package which has new-style classes and methods for spatial data, version 0.7-9.

Spatial data types that sp implements are: points, grids, lines, and polygons (i.e., rings) optionally with holes. Methods include

+ the usual print, summary, plot, [, [[, $, ...
+ coercion between types (e.g. points and grids, matrices, data.frames)
+ coordinates(x), which returns the spatial coordinates of x
+ bbox(x), returns the coordinates bounding box of x
+ overlay, to query the value of e.g. points in polygons or grid

   (essentially does a point-in-polygon or point-in-raster cell) + spsample, for random sampling methods over a spatial domain.

An additional package (spproj) provides coordinate reference system transformation (projection and re-projection) using the PROJ.4 library [2]. Others (will) provide interfaces to GRASS 6 and gdal.

A good deal of work has also gone into providing plotting methods using base, grid and lattice graphics, through the spplot function, a front-end to lattice plots for spatial data (see gallery [1]).

The home page of these packages is found at http://r-spatial.sourceforge.net/
See also the Task View on Spatial Data Analysis, linked from CRAN.

The reason why we wrote this package is that we think R is an excellent environment to deal with spatial data, but that it lacks a uniform way to deal with spatial data. Compared to the handling of dates and times, which can utilize base classes or those provided in the chron package, spatial data handling is much more fragmented. As a consequence:

It also means that many different package authors have to use time writing similar data handling code, rather than concentrating on analytical functions. If the sp package achieves its goals, data I/O will become many-to-one, and data access for analysis one-to-many, providing a shared data object layer for which shared methods can be written.

Classes and methods for spatial data are only useful when the spatial packages support them. The sp development team includes maintainers of a number of spatial R packages, on which we will work, and we hope that over time other spatial package maintainers will also provide support for the classes provided by this package.

Although we are working towards a fixed set of classes at this moment of the development of sp we cannot fully guarantee that the exact representation of the sp classes will not change in the future. Therefore, we advise users to keep the scripts with instructions of building the data into sp classes; it is most likely that we will not change the building functions and methods.

Work in progress currently involves:
- support of sp classes by several spatial statistics packages

The development of this package is a joint effort of Virgilio Gomez-Rubio, Barry Rowlinson, Roger Bivand and Edzer Pebesma, and followed from discussions held at a pre-DSC2003 workshop [3], announcements on R-sig-geo [4], and a meeting held last November in Lancaster [5]. A beta release of sp was announced a while ago on R-sig-geo [6].

With best regards,

--
Roger Bivand and Edzer Pebesma


[1] http://r-spatial.sourceforge.net/
[2] http://www.remotesensing.org/proj/
[3] http://spatial.nhh.no/meetings/vienna/index.html
[4] e.g. https://stat.ethz.ch/pipermail/r-sig-geo/2003-October/000028.html
[5] http://elearning.maths.lancs.ac.uk:8080/RSpatial/
[6] https://stat.ethz.ch/pipermail/r-sig-geo/2005-April/000378.html

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Received on Sat Jun 18 00:36:43 2005

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