[Numpy-discussion] random permutation

Sebastian Haase seb.haase at gmx.net
Sat Jan 13 13:58:53 CST 2007


On 1/13/07, Keith Goodman <kwgoodman at gmail.com> wrote:
> On 1/13/07, Sebastian Haase <seb.haase at gmx.net> wrote:
> > On 1/13/07, Keith Goodman <kwgoodman at gmail.com> wrote:
> > > On 1/11/07, Robert Kern <robert.kern at gmail.com> wrote:
> > > > Keith Goodman wrote:
> > > > > Why is the first element of the permutation always the same? Am I
> > > > > using random.permutation in the right way?
> > > >
> > > > >>> M.__version__
> > > > > '1.0rc1'
> > > >
> > > > This has been fixed in more recent versions.
> > > >
> > > >   http://projects.scipy.org/scipy/numpy/ticket/374
> > >
> > > I don't see any unit tests for numpy.random. I guess randomness is hard to test.
> > >
> > > Would it help to seed the random number generator and at least check
> > > that you get the same result you got before? No existing problems
> > > would be found. But new ones might be caught.
> > >
> > Hi,
> > Is it guaranteed that a given seed produces the same sequence of
> > rand-number between different platforms ?
> > I thought this might only be guaranteed for "any given computer" to
> > reproduce the same numbers.
>
> I hope, and expect, that it is system independent.
>
> Here's what I get:
>
> >> rs = numpy.random.RandomState([123, 901, 789])
> >> rs.randn(4,1)
>
> array([[ 0.76072026],
>       [ 1.27712191],
>       [ 0.03497453],
>       [ 0.09056668]])
> >> rs.rand(4,1)
>
> array([[ 0.184306  ],
>       [ 0.58967936],
>       [ 0.52425903],
>       [ 0.33389408]])
> >> numpy.__version__
> '1.0.1'
>
> Linux kel 2.6.18-3-686 #1 SMP Mon Dec 4 16:41:14 UTC 2006 i686 GNU/Linux
import numpy
rs = numpy.random.RandomState([123, 901, 789])
rs.randn(4,1)
[[ 0.76072026]
[ 1.27712191]
[ 0.03497453]
[ 0.09056668]]
rs.rand(4,1)
[[ 0.184306  ]
[ 0.58967936]
[ 0.52425903]
[ 0.33389408]]
numpy.__version__
'1.0rc1'

Windows XP- pentium4  - (non current numpy) -

Looks promising - but how about PowerPC macs ...
-Sebastian


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