Howto set iindividual vertex positions/coordinates by hand

As you can see from the script, I use attributes vXCoord and vYCoord to handle position.
What is the proper way in graph-tool to handle vertex pos ?
Is there a way to set a vertex pos by hand ?

The script works fine.

script.py (736 Bytes)
graph_1.xml (3.0 KB)

Please read the documentation on property maps: Quick start guide — graph-tool 2.80 documentation