def _init_spatial_properties(self, shape, positions=None, **kwargs):
'''
Create the positions of the neurons from the graph `shape` attribute
and computes the connections distances.
'''
if shape is not None:
shape.set_parent(self)
self._shape = shape
else:
self._shape = Shape.rectangle(self,1,1)
if positions is not None and positions.shape[1] != self.node_nb():
raise InvalidArgument("Wrong number of neurons in `positions`.")
b_rnd_pos = True if not self.node_nb() or positions is None else False
self._pos = self._shape.rnd_distrib() if b_rnd_pos else positions
Connections.distances(self)
