--- lammps-23Mar16/python/lammps.py	(original)
+++ lammps-23Mar16/python/lammps.py	(refactored)
@@ -208,7 +208,7 @@
       result = (c_double*nlocal)()
       self.lib.lammps_extract_variable.restype = POINTER(c_double)
       ptr = self.lib.lammps_extract_variable(self.lmp,name,group)
-      for i in xrange(nlocal): result[i] = ptr[i]
+      for i in range(nlocal): result[i] = ptr[i]
       self.lib.lammps_free(ptr)
       return result
     return None