spgrass6 : diferent values from original

Checking the result on the readRAST6, I noticed that
the number of bytes are 2, and I need 4 bits to store
values greather than 32565, I suppose.
--------------
mapa <- readRAST6(varint, cat=FALSE)
Creating BIL support files...
Header File =
C:/Data/Tibagi/vegPR_probio_proatlan_abr2009/tibagi_Probio_grass_sdb_apr2009/newLocation/PERMANENT/.tmp/uso_tibagi_fundo_soflor_ero30m_dila030m_mata_clump.hdr
World File =
C:/Data/Tibagi/vegPR_probio_proatlan_abr2009/tibagi_Probio_grass_sdb_apr2009/newLocation/PERMANENT/.tmp/uso_tibagi_fundo_soflor_ero30m_dila030m_mata_clump.wld
Exporting raster as integer values (bytes=2)
Using the current region settings...
--------------------
But how can I chance the number of bytes, if it is not an
argument on readRAST6?
Thanks for including your sessionInfo() in the preceding mail. If you are 
still using 0.5-10, you have no choice but to cast the data to floating 
point using r.mapcalc (add 0.0 should do it). There have been many changes 
in readRAST6() since that version, for example to use a GRASS GDAL plugin 
if available, and to use GDAL to read and write GTiff temporary files. The 
older route using r.out.bin only offers 2-byte integers, so was a reason 
for making more formats available.

So the answer in general is to update sp, spgrass6 and rgdal if you can. 
Since you in addition on Windows, and probably using the Native Windows 
version, until a new release you will hit a snag that more recent GRASS 
r.out.gdal have a -c flag which is not in your release - here you can wait 
for the next release, and use the trick of casting to floating point until 
then.

Roger
Best wishes

miltinho

On Sun, Mar 29, 2009 at 12:43 AM, milton ruser <milton.ruser at gmail.com>wrote:

Hi there,

I have a set of maps on GRASS 6.5 and I need to compute some basic stats
on R 2.7.1. For some maps I get the desired results, but for other I am
getting different values. My raster are integer values >= 1 (with some NAs
where not mapped).

I start R from GRASS session without problem, and can read the rasters
on R:

require(spgrass6)
varint<-"uso_tibagi_fundo_soflor_ero30m_dila030m_mata_clump_AreaHA"
mapa <- readRAST6(varint, cat=FALSE)
mapa.valores<-mapa at data[1]
mapa.valores<-mapa.valores[!is.na(mapa.valores)]
quantile(mapa.valores, probs=c(0.20,0.40,0.60,0.80))
summary(mapa.valores)
rm(mapa, mapa.valores,varint)
But for one of my map I get different range of value between R and GRASS
ON GRASS - r.univar
n: 8336636
minimum: 1
maximum: 303396
range: 303395
mean: 125949

ON R
summary(mapa at data[1])
 uso_tibagi_fundo_soflor_dila030m_clump_mata_limpa_AreaHA
 Min.   :  -24284
 1st Qu.:  -24284
 Median :      31
 Mean   :   -6551
 3rd Qu.:    2225
 Max.   :   27846
 NA's   :59217475

-----> sessionInfo()
R version 2.7.1 (2008-06-23)
i386-pc-mingw32
locale:

LC_COLLATE=English_Canada.1252;LC_CTYPE=English_Canada.1252;LC_MONETARY=English_Canada.1252;LC_NUMERIC=C;LC_TIME=English_Canada.1252
attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base
other attached packages:
[1] spgrass6_0.5-10 rgdal_0.5-25    sp_0.9-26
loaded via a namespace (and not attached):
[1] grid_2.7.1     lattice_0.17-8
Any help are welcome.

Regards

miltinho
Toronto, CA

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spgrass6 : diferent values from original

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