Package: GRASS
Version: 0.2-2
Author: Interface functions by Roger Bivand <Roger.Bivand@nhh.no>, wrapper
	and helper functions modified from various originals by interface 
	author.
	
Description: Interface between GRASS geographical information system and R,
	based on starting R from within the GRASS environment and chosen 
	LOCATION and MAPSET. Wrapper and helper functions are provided for 
	a range of R functions to match the interface metadata structures. 

Note:	(0.2-2) simplified installation to eliminate dependence on GRASS
	installed tree, by making compilation self-contained. Files from
	grass*/src/libes/gis and header files, as well as header files from
	the R src/extra directories (for zlib and xdr) included. libgis files
	modified where necessary to accommodate MinGW differences.

When the library is loaded, a check is run using the environment variable
GISRC. Under Unix and Windows, it points to the file using the full path
name, but under CygWin it may lack a prefix to the CygWin root, defined
in cygpath --mixed form, such as "c:/cygwin". In this case, a warning will
be issued, the string should be set using set.cygwinstring(<your cygwin root>),
and GRASS.connect() re-run to ensure that the file named in GISRC is found
correctly. See also the GRASS.connect() help page.

> library(GRASS)
No GRASS environment found
If GRASS.connect() fails in this way and you are running under CygWin,
please set the CygWin root file system prefix using: set.cygwinstring()
Warning message:
Failure opening GISRC file
> set.cygwinstring("c:/cygwin")
[1] "c:/cygwin"
> GRASS.connect()
GRASS environment variables in: c:/cygwin/home/rsb/.grassrc5
> 

	(0.2.1) provided compiled interface for sites; corrected interpreted
	gmeta for lat/lon coordinates.

	(0.1-10/11) Changes made to accommodate changes in R with respect to
	function namespaces, and changes in which shell variables are set
	in GRASS. Changes were also made to the install scripts.

	(0.1-7/8) (release 8 tidies up minor incompatibilities with R 1.4.0)
	These releases add quantization and colours support to the raster
	interface from R to GRASS (rast.put()).

	Remarks below about the use of "R CMD check" should be ignored -
	the "check" script is now only intended for package writers and
	maintainers - not users.

	Installing continues to be done with R INSTALL GRASS_0.1-8.tar.gz.
	There are a number of configure flags that may be used to help
	the R install script find the GRASS libraries: they are

	--configure-args=--grass5= (full path to your grass5 script)
	--configure-args=--gmake5= (full path to your gmake5 script)
	--configure-args=--zinclude= (full path to directory with zlib.h)
	--configure-args=--zlib= (full path to directory with libz.a)
	--configure-args=--interp (don't build compiled interface)

--------------------------------------------------------------------

	(0.1-6) Incompatibility between R 1.1.1 and 1.2.0 in compiled 
	interface code - changes in memory management in R made changes in 
	source code necessary. The configure script will also look for the 
	include and library files in the GRASS install directory.

	(0.1-5) Major modification to examples now using Burrough & McDonnell
	Maas bank soil pollution data. Minor changes to interface functions
	to catch infelicities. From version 0.1-5, this means that you
	need to run R CMD check GRASS as:

	R CMD check --vsize=16M GRASS

	until R 1.2.0 changes the memory heap allocation mechanisms.
	

	-------------------------------

	From version 0.1-4, changes have been made in gmeta(). The function
	no longer returns the list xy with members east and north, nor obsno,
	nor reverse. These are now available as access functions, to be called
	on demand as east(G), north(G), obsno(G), and reverse(G), where
	G is an object with class "grassmeta" returned by gmeta(). This
	reduces the memory needs of "grassmeta" class objects by 24*Ncells
	bytes, where Ncells=rows*columns in the GRASS raster database for the
	current region.

	From this version, installation will try to guess the location of
	GRASS header and library files, but can chose to install interpreted:
	R INSTALL --configure-args=--interp GRASS_0.1-4.tar.gz

	The location of gmake5 can also be given:
	R INSTALL --configure-args=--gmake5=<...> GRASS_0.1-4.tar.gz
	when the package does not find it itself using which gmake5.

	-------------------------------

	From version 0.1-3, the interface includes compiled functions for 
	gmeta(), rast.put(), and rast.get(). These link against the GRASS 
	library libgis.a and require the include file gis.h.
 
	These are available on systems - 
	essentially only Unix/GNU Linux systems - on which GRASS has itself been
	compiled, and are not included in GRASS binary distributions. A simple
	configure script is used to look for the required files, searching first
	for the gmake5 script, and next setting appropriate flags for compiling
	and linking.

	The speed-up from using compiled interface functions is at least an
	order of magnitude, varying for transfer of category labels/factor 
	levels and numeric/floating point layers. R factor levels can only be
	moved to GRASS as category labels in the compiled version of rast.put().
	There are detailed differences in the handling of factor levels/cate-
	gory labels between the interpreted and compiled versions of rast.get().
	
	Care needs to be taken with R's assumptions about the factor and
	ordered attributes - partly because R expects the factor values to
	point to level array elements, which begin at 1, not 0 as in C (and
	thus in the GRASS Categories structure. Running table() on the
	ordered factor imported with interp=[FT] in rast.get(), or on
	the unclass() of the imported ordered factors will show which pointers
	were assigned. The mapping is still one-to-one, but the values differ
	from those in the original GRASS layer.

	Further, the compiled interfaces, although protected by ad hoc checks, 
	do call functions in libgis.a which include calls to exit() from C, 
	and can therefore abort R sessions. The user may wish to save the R 
	session with save.image() before risking losing data from memory. 
	
	Safer versions of libgis.a functions will enter the GRASS code base 
	in time; for now a copy of modified versions of env.c, error.c, and 
	get_row.c from the grass5.0beta7 codebase may be found at: 

	ftp://reclus.nhh.no/pub/misc/libes.gis.tar.gz
	
