[Matrix-SIG] Reading and handling matrices.

Konrad Hinsen hinsen@cnrs-orleans.fr
Wed, 28 Apr 1999 21:23:17 +0200

> minimal swapping and even on a 128 Mb machine it was bearable. With Python
> I had to resort to a 256 Mb machine (since, at one point, it has to hold
> the first array, the second array as an array, and also the second array
> as a string while conversion takes place). 

You could have done I/O piecewise:

    chunk_size = 5000 # or whatever you want
    linear = Numeric.ravel(array)
    file = open('binary_data', 'wb')
    i = 0
    while i < len(linear):
       i = i + chunk_size

The resulting binary file should be the same, and of course you could
use a similar trick for reading.

> IMHO, binary I/O is a frequent task in data analysis and it would make
> sense to add a tofile() and a fromfile() method for NumPy arrays, even in
> the absence of any efficiency considerations... 

Some routine like the above in Numeric would probably be sufficient,
but I agree it should be there.

On a related issue: somewhat should implement a cPickle interface for
array objects. It's on my to-do list, but unfortunately not very
high up!
Konrad Hinsen                            | E-Mail: hinsen@cnrs-orleans.fr
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