I use PyLammps in iPython (jupyter notebook) in my Mac. The input is based on .in file in /examples/melt and translate it to PyLammps format according to manual. But when I input “L.atoms.position”, the iPython breakdown immediately. Different lists or objects, such on runs, system, fixes, computes, don’t occur the problem.
please update LAMMPS to the latest version (23 Oct 2017 currently) and try again.