Here is a simple example. This one resets position of select object to world center :)
import c4d
from c4d import gui
#Welcome to the world of Python
selected = doc.GetActiveObjects(0)
for obj in selected:
doc.AddUndo(c4d.UNDOTYPE_CHANGE, obj)
obj.SetRelPos(c4d.Vector(0,0,0))
c4d.EventAdd()