R help - Oct 2011 - rpy2 pie chart

I am trying to create a pie chart using rpy2 of the following data

Pathway  Occurrences
A               10%
B                50%
C                20%
E                10%

filename = './testing.png'
grdevices = importr('grDevices')
rdevices.png(file=filename, width=1200, height=800)
    dataf = Robjects.DataFrame({'pathways':Robjects.StrVector(Pathways),
                                occurrences' :
Robjects.FloatVector(Occurrences)
                                })
    pie = ggplot2.ggplot(dataf)+ \
   
ggplot2.aes_string(x='',fill='pathways',weight="amounts")+\
    ggplot2.geom_bar(width=1)+\
    ggplot2.coord_polar(theta="y")
    pie.plot()
    grdevices.dev_off()

but this is not producing the pie chart needed where is the problem?

How to I rename the x and y lables?

-- 
Regards/Groete/Mit freundlichen Grüßen/recuerdos/meilleures salutations/
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Jurgens de Bruin

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