Here is a sample function that takes any sensor object and calculates the speed of it:
Code:
import viz
viz.go()
sensor = viz.add('testtrack_all.dls')
def CalculateSpeed(obj):
#Get current and last position
current_pos = obj.getPosition()
last_pos = getattr(obj,'last_pos',None)
if last_pos is None:
#This is first call, so save position and set speed to 0
obj.last_pos = current_pos
obj.speed = 0.0
else:
#Compute speed using last position
obj.speed = vizmat.Distance(current_pos,last_pos) / viz.elapsed()
obj.last_pos = current_pos
print obj.speed
vizact.ontimer(0,CalculateSpeed,sensor)