#go into solvers menu and create particle disk cache before you run script.
#this script will calcuate the position or each particle and return a unit vector

from math import sqrt
import pickle
import maya.cmds as cmds	

time = cmds.currentTime( query=True )
timeStep = 10

sel = cmds.ls (sl=True)	
print(sel[0])
ptcount = cmds.getAttr (sel[0] + '.count')
print(ptcount)

for i in range(0, ptcount):		

	cmds.currentTime( str(time), edit=True )
	cmds.select (sel[0] + '.pt[' + str(i) + ']', r=True)
	pos = cmds.getParticleAttr (sel[0] + '.pt[' + str(i) + ']' , at ='worldPosition' )
	print(pos)

	cmds.currentTime( str(time+timeStep ), edit=True )
	posTwo = cmds.getParticleAttr (sel[0] + '.pt[' + str(i) + ']' , at ='worldPosition' )

	vx = pos[0] - posTwo[0]
	vy = pos[1] - posTwo[1]
	vz = pos[2] - posTwo[2]

	magnatude = sqrt((vx * vx) + (vy * vy) + (vz * vz)) 	

	normVector = [vx/magnatude,vy/magnatude,vz/magnatude]
	print(normVector)