g.vp["pos"]

g = load_graph('mydata.gml')
state = gt.minimize_blockmodel_dl(g)
b = state.b
gt.graph_draw(g, inline=True, pos=g.vp["pos"], vertex_fill_color=b,
vertex_shape=b, output="mydata.pdf")

This leads to the following error:

----> 3 gt.graph_draw(g, inline=True, pos=g.vp["pos"], vertex_fill_color=b,
vertex_shape=b, output="2013_blocks_mdl.pdf")

/usr/lib/python2.7/dist-packages/graph_tool/__init__.pyc in
__getitem__(self, key)
   1419 p = self.properties[(self.t, key)]
   1420 return p[p.get_graph()]
-> 1421 return self.properties[(self.t, key)]
   1422
   1423 def get(self, key, default=None):

KeyError: ('v', 'pos')

My question is what g.vp["pos"] does?

Thanks

It retrieves an internal vertex property map named "pos". Please read
the documentation:

    https://graph-tool.skewed.de/static/doc/quickstart.html#internal-property-maps

Best,
Tiago