I was looking at python's whrandom and random modules the other day.
Both seem to have a period of 27814431486575L (30268*30306*30322-1),
which is, of course, quite a number, but not that long anyway. So I
thought, why not use SHA1 in the core generator? Perhaps something
along these lines:
#v+
import sys, os, time, sha
class SHARandom:
def __init__(self, x = 0, y = 0, z = 0):
self._max = float(long('f'*40,16)+1)
self._sha = sha.new()
self.seed(x, y, z)
# end def __init__
def seed(self, x = 0, y = 0, z = 0):
if not x: x = `time.time()`
if not y: y = os.getpid()
if not z: z = os.getcwd()
self._sha.update(str(x))
self._sha.update(str(y))
self._sha.update(str(z))
# end def seed
def random(self):
self._hash = self._sha.digest()
self._sha.update(self._hash)
return float(long(self._sha.hexdigest(), 16)) / self._max
# end def random
# [ methods omitted for brevity ]
# end class SHARandom
# Initialize from the current time
_inst = SHARandom()
seed = _inst.seed
random = _inst.random
uniform = _inst.uniform
randint = _inst.randint
choice = _inst.choice
randrange = _inst.randrange
#v-
It is probably quite expensive to use the sha module for shuffling
the bits, but the resulting period is huge.
What do you guys think? Is it worth it? I meant to use it for
generating uuids, but perhaps it's overkill?
// Klaus
--
><> unselfish actions pay back better