ScaleDistance

from pymel.core import *
import maya.api.OpenMaya as om
import time
import math
def getPiv(s):
    select(s)
    setToolTo('Move')
    piv = manipMoveContext('Move', q=True, p=True,m=2)
    return piv
def getDist(p1,p2):
    dist = math.sqrt((p1[0] - p2[0])**2 + (p1[1] - p2[1])**2 + (p1[2] - p2[2])**2)
    return dist
start = time.clock()
#sl = selected()
tStart = playbackOptions(q=1,ast=1)
tEnd = playbackOptions(q=1,aet=1)
objects = sl[:-1]
lctr = sl[-1]

fallOffAmnt = 100
startScale = 2
offsetAmnt = 2
i = 0
for f in range(int(tStart),int(tEnd)+1):
    lctrPos = getPiv(lctr)
    DistCheck = getAttr(lctr+".scale")[0] # Radius
    lctrPos = om.MVector(lctrPos)

    currentTime(i, u=1)
    for o in objects:
        dPos = getPiv(o)
        direction = om.MVector(lctrPos) - om.MVector(dPos)
        directionN = direction.normalize() * offsetAmnt

        objScale = startScale#d[0].getScale()
        directionMag = directionN.length()
        distFar =  getDist(directionN, dPos)
        distNear =  getDist(lctrPos, directionN)

        if distFar < DistCheck:
            fallOff = distFar / DistCheck  # scales down/ mapps to 0-1
            newScale =  (objScale * fallOff)# + offset
            scale(o, newScale, newScale, newScale)
            if newScale < 0.1:
                scale(o, 0, 0, 0)

        elif distNear < directionMag:
            scale(o, 0, 0, 0)
            print "cat"
        else:
             scale(o, objScale,objScale,objScale)

        setKeyframe(o+".scale")

    i += 1

elapsedChunk = (time.clock() - start)
print "done, took:", elapsedChunk