rpy2 postgres qgis problem

Hello every body,
I am using rpy2_2.0.8  with postgres and Qgis.
The code that I wrote is the following:

def on_calcola_pressed (self):
                # bottone per calcoli statistici
                import rpy2
                import rpy2.robjects as robjects
                import rpy2.robjects as ro

                r = robjects.r
                robjects.r

                r.library("RPostgreSQL")
                r.library("gstat")
                r.library("zoo")
                rcmd_drv = r["dbDriver"]
                rcmd_con = r["dbConnect"]
                rcmd = r["dbListTables"]
                rcmd_archezoology_table = r["dbReadTable"]
                png = r.png
                drv = rcmd_drv("PostgreSQL")
                con = rcmd_con(drv, host="127.0.0.1", dbname="pyarchinit",
port="5432", password="enzo", user="postgres")
                archezoology_table =
rcmd_archezoology_table(con,"archeozoology_table")

r.png(file="/home/enzo/Scrivania/prova.png",width=512,height=512)
                plot = r.plot
                zoo = r.zoo
                ('VGM_PARAM_A3 <- gstat(id="bos_bison",
formula=combusto~1,locations=~coord_x+coord_y, data=archezoology_table,
nmax = 10) VGM_PARAM_A3 <- gstat(VGM_PARAM_A3, "calcinati", strie~1,
locations=~coord_x+coord_y, archezoology_table, nmax = 10)VGM_PARAM_A3 <-
gstat(VGM_PARAM_A3, "camoscio", cervo~1,
locations=~coord_x+coord_y,archezoology_table, nmax = 10) VGM_PARAM_A3 <-
gstat(VGM_PARAM_A3, model=vgm(1, "Sph", 5, 0), fill.all=TRUE ESV_A3 <-
variogram(VGM_PARAM_A3, cutoff=9) VARMODEL_A3 = fit.lmc(ESV_A3,
VGM_PARAM_A3)')
                plot(zoo('ESV_A3, model = VARMODEL_A3,xlab=,ylab=,pch=20,
cex=0.7, col="red",main="Linear Model of Coregionalization for A3
variables"'))

The error is the following:

 res = super(RFunction, self).__call__(*new_args, **new_kwargs)
RRuntimeError: Error in plot.window(...) : invalid 'ylim' value



Do you have a suggestion or examples about how to call a function with the
gistat module on a postgress tab using rpy2?

Thank you,

Enzo

--
Enzo Cocca (PhD Candidate)
Research Fellow
Universit? di Napoli "L'Orientale"
mail: enzo.ccc at gmail.com
cell: +393495087014

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