I'm using Pyx to plot this file:
SAGE    Q_RT-PCR    Genes
9.61    22.36        Adiponectin
5.73    -19.16        Acyl-Coenzyme A dehydrogenase, very long chain
-8.46    -21.25        1-acylglycerol-3-phosphate O-acyltransferase 2
-10.68    -26.45        Fatty acid synthase
8.53    23.44        Lipoprotein lipase
9.39    23.77        Cell death-inducing DFFA-like effector c
5    20.65        Angiotensinogen
7.73    23.93        Neuronatin

My actual script looks like this:
from pyx import *

g = graph.graphxy(width=8,
    x=graph.axis.lin(min=-15, max=15, title="SAGE"),
    y=graph.axis.lin(min=-30, max=30, title="RT-PCR"),

g.plot(graph.data.file ("explevels.dat", x=1, y=2))

I would like to add a legend for each of the point. So each point should have a different shape and/or color and the legend should correspond to the 3rd column of the input file (Genes).

How should I proceed?