whrandom seed question

[Michael Hudson]

kyriacou at umbc.edu (Stelios Kyriacou) writes:

> Hi, 
> 
> I tried today the random number generator in python 
> and have the following question: 
> 
> Shouldn't the following 3 lines produce the same number? 
> 
> >>> whrandom.seed(0,0,0); print whrandom.random() 
> 0.39613674715 
> >>> whrandom.seed(0,0,0); print whrandom.random() 
> 0.170188890936 
> >>> whrandom.seed(0,0,0); print whrandom.random() 
> 0.831213988577 
> >>> 

Use the source luke!

>From /usr/lib/python1.5/whrandom.py:

        def seed(self, x = 0, y = 0, z = 0):
                if not type(x) == type(y) == type(z) == type(0):
                        raise TypeError, 'seeds must be integers'
                if not (0 <= x < 256 and 0 <= y < 256 and 0 <= z < 256):
                        raise ValueError, 'seeds must be in range(0, 256)'
                if 0 == x == y == z:
                        # Initialize from current time
                        import time
                        t = long(time.time() * 256)
                        t = int((t&0xffffff) ^ (t>>24))
                        t, x = divmod(t, 256)
                        t, y = divmod(t, 256)
                        t, z = divmod(t, 256)
                # Zero is a poor seed, so substitute 1
                self._seed = (x or 1, y or 1, z or 1)

So

>>> whrandom.seed(1,1,1); print whrandom.random()
0.0169309061997
>>> whrandom.seed(1,1,1); print whrandom.random()
0.0169309061997
>>> whrandom.seed(1,1,1); print whrandom.random()
0.0169309061997

as expected.
 
> Am I missing something??? 

New one on me that! You'd think None would be a better default.

Regards,
Michael