Hi All,

please aplogize me if my qustion is a bit OT here,
but maybe is there someone that uses R from inside python
using rpy or rpy2 interface.

i'm at my first experience using rpy2.

i need to port torpy some R code .. but i'm having little problems
i hope yopu can help me.

The R code is :

################################################
grass65
R
library(spgrass6)
r=readRAST6("elevation.10m")
r_sorted=sort(r@data$elevation.10m,decreasing=T)
p_seq=seq(1,length(r_sorted)) #area
x=p_seq/length(r_sorted)
x=(x-min(x))/(max(x)-min(x))
y=(r_sorted-min(r_sorted))/(max(r_sorted)-min(r_sorted))
result=data.frame(x,y)
png("graphic.png") # oppure ("graphic.pdf")
plot(result,type="l",x)
plot(result,type="l", xlab="area", ylab="elevation")
dev.off()
################################################


i tried to write it in python-rpy2 :


################################################

# import library (rpy2 + spgrass6)

import rpy2.rinterface as rinterface
import rpy2.robjects as robjects
robjects.r.require('spgrass6', quietly = True)[0]

# def some functions :
rsort = robjects.r['sort']
rseq = robjects.r['seq']
rlength = robjects.r['length']
rdiv = robjects.r['/']
rmin = robjects.r['min']
rmax = robjects.r['max']
rdiff = robjects.r['-']

# read input file
mymap = robjects.r.readRAST6(inputmap)
elev = rsort('mymap@data$inputmap', decreasing=True)
r_sorted = rsort('mymap@data$elevation.dem', decreasing=True)
p_seq = rseq(1,rlength(r_sorted))
x = rdiv(p_seq,length(r_sorted))
x = rdiv( ( rdiff( x, rmin(x) ) ) , ( rdiff( rmax(x) , rmin(x) ) ) )
y = rdiv( ( rdiff( r_sorted, rmin(r_sorted) ) ) , ( rdiff( rmax(r_sorted) , rmin(r_sorted) ) ) )
.... errors
################################################


but maybe it is totally wrong... 
this the same code running in ipython.

tring to run it i have :


In [38]: import rpy2.rinterface as rinterface

In [39]: import rpy2.robjects as robjects

In [40]: robjects.r.require('spgrass6', quietly = True)[0]
Out[40]: True

In [41]: rsort = robjects.r['sort']

In [42]: rseq = robjects.r['seq']

In [43]: rlength = robjects.r['length']

In [44]: rdiv = robjects.r['/']

In [45]: rmin = robjects.r['min']

In [46]: rmax = robjects.r['max']

In [47]: rdiff = robjects.r['-']

In [48]: inputmap = 'elevation.dem'

In [49]: mymap = robjects.r.readRAST6(inputmap)
raster map/current region mismatch detected in components:
           cols            rows origin.northing  origin.easting 
          FALSE           FALSE           FALSE           FALSE 
set plugin=TRUE to override; continuing with plugin=FALSE
/Users/sasha/Downloads/spearfish60/PERMANENT/.tmp/MacBook-Pro-15-di-Massimo-Di-Stefano.local/elevation.dem has GDAL driver GTiff 
and has 140 rows and 190 columns

In [50]: elev = rsort('mymap@data$inputmap', decreasing=True)

In [51]: r_sorted = rsort('mymap@data$elevation.dem', decreasing=True)

In [52]: p_seq = rseq(1,rlength(r_sorted))

In [53]: x = rdiv(p_seq,length(r_sorted))

In [54]: x = rdiv( ( rdiff( x, rmin(x) ) ) , ( rdiff( rmax(x) , rmin(x) ) ) )

In [55]: y = rdiv( ( rdiff( r_sorted, rmin(r_sorted) ) ) , ( rdiff( rmax(r_sorted) , rmin(r_sorted) ) ) )
Errore in .Primitive("-")("mymap@data$elevation.dem", "mymap@data$elevation.dem") : 
  argomento non numerico trasformato in operatore binario
------------------------------------------------------------
Traceback (most recent call last):
  File "<ipython console>", line 1, in <module>
  File "build/bdist.macosx-10.6-universal/egg/rpy2/robjects/__init__.py", line 423, in __call__
RRuntimeError: Errore in .Primitive("-")("mymap@data$elevation.dem", "mymap@data$elevation.dem") : 
  argomento non numerico trasformato in operatore binario

################################################
################################################


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regards,
Massimo.
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