Nupic Coordinate Encoder Union percentage

gistfile1.py

#!python

import numpy as np
import random as r

import nupic
from nupic.encoders.coordinate import CoordinateEncoder as Enc

e=Enc(w=25, n=1000)
print e
output = np.zeros(e.getWidth())
coord = np.array([3, 9])
radius = 1
print e.encodeIntoArray((coord, radius), output)
print output

print e.encodeIntoArray((np.array([4, 9]), radius), output)
print output

print e.encodeIntoArray((np.array([4, 9]), 3), output)
print output

D=128
N=D*D
p=0.1
res = np.zeros(e.getWidth())


for i in range(1,int(N*p)):
  x=r.randint(1,D)
  y=r.randint(1,D)
  e.encodeIntoArray((np.array([x, y]), 1), output)
#  print i
#  print output, len(output), sum(output)
  res = np.logical_or(res, output)

print res
#print np.logical_or(np.array([0,0,1]),np.array([1,0,0]))

Q1: I try to encode XY-board (2D, with eucl. distance), is CoordinateEncoder my right choice?
--if so, can I take an advantage of the limited board? (128x128 only)

Q2: on line 29 I visit & encode 10% of the positions, I create a union of the encodings...but then in res I get a "full 1s" encoding, instead of ~10% 1s, as I'd expect! Why is that?