[Numpy-discussion] Non-numerical info associated with sub-arrays

Magnus Lie Hetland magnus at hetland.org
Fri Dec 27 16:07:03 CST 2002


Tim Churches <tchur at optushome.com.au>:
[snip]
> Just like this:
> 
> >>> import Numeric
> >>> a = Numeric.array(['a','b','c'],typecode=Numeric.PyObject)
> >>> a
> array([a , b , c ],'O')
> >>>

As you may have noticed from my previous descriptions, I'm using
numarray, not Numeric. I've used this in Numeric before -- I just
can't find the equivalent functionality in numarray :)

[snip]
> I really like MetaKit's column-based storage,

Me too.

> but it just doesn't scale
> well (on the author's admission, and verified empirically)

Yes, you're right.

> - beyond a
> few 10**5 records, it bogs down terribly, whereas memory-mapped NumPy
> plus BsdDb3 recno databse for strings scales well to many tens of
> millions of records (or more, but thats as far as I have tested).

Impressive!

Now this *does* sound interesting... The project I originally posted
about only has a few hundred records, so I'm only considering numarray
for expressiveness/readability there -- performance is not an issue.
But using bsddb and numarray (or Numeric) together like this seems
useful in many applications.

> Tim C

-- 
Magnus Lie Hetland
http://hetland.org




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