[Numpy-discussion] does an ndarray have a "hook" for a dictionary attribute ?

Sebastian Haase seb.haase at gmail.com
Thu Nov 12 04:47:18 EST 2009

On Thu, Nov 12, 2009 at 10:38 AM, Sebastian Haase <seb.haase at gmail.com> wrote:
> Hi,
> I hope my subject line is not entirely incomprehensible:
> I remember there was a discussion (some time ago) that every ndarray
> instance should get an extra dictionary (or just a "hook" for it, to
> minimize the memory foot print) for "application specific" /
> "auxiliary" data.
> What is the current state on this ?
> The issue at hand is, that my image analysis development platform
> supports various file types by now, and I usually load images straight
> into an ndarray (e.g. using PIL for standard types).
> This is fine for most needs depending only on the pixel values.
> However, now I would like to save images back after performing some
> operation on it.
> So it would be nice if I could "attach" the original filename to the
> respective ndarray.
> Is this possible with standard ndarray (using the mentioned dictionary
> attribute)
> or
> do I need to subclass ndarray to make such a ndarray_with_dict
> ?
> (For the latter it would be very helpful to get a hint on how to make
> such a "minimal" ndarray-subclass . I remember some issues involving
> some special __new__ methods, that I don't entirely remember by
> heard..)
I found the thread I was thinking of in the archive:

However, what was the outcome ... ?

Sebastian Haase

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