[Numpy-discussion] Fortran order in recarray.

Robert McLeod robbmcleod at gmail.com
Wed Feb 22 10:34:00 EST 2017


Just as a note, Appveyor supports uploading modules to "public websites":

https://packaging.python.org/appveyor/

The main issue I would see from this, is the PyPi has my password stored on
my machine in a plain text file.   I'm not sure whether there's a way to
provide Appveyor with a SSH key instead.

On Wed, Feb 22, 2017 at 4:23 PM, Alex Rogozhnikov <
alex.rogozhnikov at yandex.ru> wrote:

> Hi Francesc,
> thanks a lot for you reply and for your impressive job on bcolz!
>
> Bcolz seems to make stress on compression, which is not of much interest
> for me, but the *ctable*, and chunked operations look very appropriate to
> me now. (Of course, I'll need to test it much before I can say this for
> sure, that's current impression).
>
> The strongest concern with bcolz so far is that it seems to be completely
> non-trivial to install on windows systems, while pip provides binaries for
> most (or all?) OS for numpy.
> I didn't build pip binary wheels myself, but is it hard / impossible to
> cook pip-installabel binaries?
>
> ​You can change shapes of numpy arrays, but that usually involves copies
> of the whole container.
>
> sure, but this is ok for me, as I plan to organize column editing in
> 'batches', so this should require seldom copying.
> It would be nice to see an example to understand how deep I need to go
> inside numpy.
>
> Cheers,
> Alex.
>
>
>
>
> 22 февр. 2017 г., в 17:03, Francesc Alted <faltet at gmail.com> написал(а):
>
> Hi Alex,
>
> 2017-02-22 12:45 GMT+01:00 Alex Rogozhnikov <alex.rogozhnikov at yandex.ru>:
>
>> Hi Nathaniel,
>>
>>
>> pandas
>>
>>
>> yup, the idea was to have minimal pandas.DataFrame-like storage (which I
>> was using for a long time),
>> but without irritating problems with its row indexing and some other
>> problems like interaction with matplotlib.
>>
>> A dict of arrays?
>>
>>
>> that's what I've started from and implemented, but at some point I
>> decided that I'm reinventing the wheel and numpy has something already. In
>> principle, I can ignore this 'column-oriented' storage requirement, but
>> potentially it may turn out to be quite slow-ish if dtype's size is large.
>>
>> Suggestions are welcome.
>>
>
> ​You may want to try bcolz:
>
> https://github.com/Blosc/bcolz
>
> bcolz is a columnar storage, basically as you require, but data is
> compressed by default even when stored in-memory (although you can disable
> compression if you want to).​
>
>
>
>>
>> Another strange question:
>> in general, it is considered that once numpy.array is created, it's shape
>> not changed.
>> But if i want to keep the same recarray and change it's dtype and/or
>> shape, is there a way to do this?
>>
>
> ​You can change shapes of numpy arrays, but that usually involves copies
> of the whole container.  With bcolz you can change length and add/del
> columns without copies.​  If your containers are large, it is better to
> inform bcolz on its final estimated size.  See:
>
> http://bcolz.blosc.org/en/latest/opt-tips.html
>
> ​Francesc​
>
>
>>
>> Thanks,
>> Alex.
>>
>>
>>
>> 22 февр. 2017 г., в 3:53, Nathaniel Smith <njs at pobox.com> написал(а):
>>
>> On Feb 21, 2017 3:24 PM, "Alex Rogozhnikov" <alex.rogozhnikov at yandex.ru>
>> wrote:
>>
>> Ah, got it. Thanks, Chris!
>> I thought recarray can be only one-dimensional (like tables with named
>> columns).
>>
>> Maybe it's better to ask directly what I was looking for:
>> something that works like a table with named columns (but no labelling
>> for rows), and keeps data (of different dtypes) in a column-by-column way
>> (and this is numpy, not pandas).
>>
>> Is there such a magic thing?
>>
>>
>> Well, that's what pandas is for...
>>
>> A dict of arrays?
>>
>> -n
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>>
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>
>
> --
> Francesc Alted
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>
>
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>


-- 
Robert McLeod, Ph.D.
Center for Cellular Imaging and Nano Analytics (C-CINA)
Biozentrum der Universität Basel
Mattenstrasse 26, 4058 Basel
Work: +41.061.387.3225
robert.mcleod at unibas.ch
robert.mcleod at bsse.ethz.ch <robert.mcleod at ethz.ch>
robbmcleod at gmail.com
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