[Numpy-discussion] python eats memory like the cookie monster eats cookies

[Niels Provos]

The missing imports are

import Numeric # for zeros and ones
from scipy.fftpack import fft2,ifft2

Curiously, replacing Numeric.zeros with scipy.zeros makes the problem
go away.  Why?

Thank you,
 Niels.

On 2/4/07, Robert Kern <robert.kern@gmail.com> wrote:
> Niels Provos wrote:
> > Good morning,
> >
> > not sure if I got the right list, but I hope that somebody here will
> > be able to shed some light on a Python-related memory problem.  The
> > following code eats over >2GB of memory and fails with MemoyError
> > after just a few iterations.
> >
> > def ZeroPadData(A, shape):
> >     a = Numeric.zeros(shape, 'w')
> >     a.savespace()
> >
> >     for y in xrange(A.shape[0]):
> >         for x in xrange(A.shape[1]):
> >             a[y, x] = A[y, x]
> >
> >     return a
> >
> > def EatMemoryLikeTheCookieMonster(limit=10):
> >     A = Numeric.ones([1998, 3022])
> >
> >     count = 0
> >     a = A
> >     while count < limit:
> >         print count
> >         count += 1
> >
> >         a = ZeroPadData(a, [2048, 4096])
> >
> >         b = fft2(a)
> >         b = ifft2(b)
> >
> >         a = b[:1998,:3022].real
> >
> > EatMemoryLikeTheCookieMonster()
> >
> > This is for Python 2.4.3 on Mac OS X 10.4.8 (intel) using SciPy 0.5.2.
>
> Could you also post a complete example? Why are you using Numeric? scipy 0.5.2
> requires numpy, not Numeric. Where are the fft2() and ifft2() functions coming
> from, scipy.fftpack or numpy?
>
> --
> Robert Kern
>
> "I have come to believe that the whole world is an enigma, a harmless enigma
>  that is made terrible by our own mad attempt to interpret it as though it had
>  an underlying truth."
>   -- Umberto Eco
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