[SciPy-Dev] GSoC 2014 : Discrete Wavelets Transform

[Ralf Gommers]

On Mon, Mar 17, 2014 at 10:05 PM, Ankit Agrawal <aaaagrawal at gmail.com>wrote:

> The above posted proposal link is broken probably because of the ending
> bracket. Here<https://github.com/scipy/scipy/wiki/GSoC-2014-:-Discrete-Wavelet-Transform-proposal-draft> is
> the link in its full glory.
>
> Regards,
> Ankit Agrawal,
> Communication and Signal Processing,
> IIT Bombay.
>
>
> On Tue, Mar 18, 2014 at 2:05 AM, Ankit Agrawal <aaaagrawal at gmail.com>wrote:
>
>> Hi everyone,
>>
>>         I apologize for not responding fast enough as I was consumed by
>> some assignment deadlines until today.
>>
>>         The draft of my proposal is ready and can be found here<https://github.com/scipy/scipy/wiki/GSoC-2014-:-Discrete-Wavelet-Transform-(draft)>.
>> Please review it. Any suggestions for changes/improvements are welcome.
>> Thanks.
>>
>> @Ralf and Stefan : Does the timeline and the chronological order of tasks
>> seem good to you?
>>
>
The order of tasks looks sensible. I would expand the descriptions in some
cases a little bit.

For integration into scipy you could say what the tasks are (I expect
adding code and making it build is very quick, adding docs and a small
tutorial may be part of this task).

For 1d/2d SWT one week should be enough I think. There are Python
implementations already posted on the PyWavelets list, moving those to
C/Cython and testing them should be doable fairly quickly.

For image compression algorithm I'd expect more details on which ones
exactly. Maybe worth discussing on the scikit-image list what they'd like
to see. JPEG 2000 isn't in the Matlab toolbox you linked but may be a good
candidate. I think the patent issues with JPEG are history.

You made two more PRs in the meantime, I'd link those as well. And please
remind me if I haven't reviewed/merged your changes to the thresholding
functions before the deadline.

Cheers,
Ralf



>>
>> Regards,
>> Ankit Agrawal,
>> Communication and Signal Processing,
>> IIT Bombay.
>>
>>
>> On Sat, Mar 15, 2014 at 9:37 PM, Ralf Gommers <ralf.gommers at gmail.com>wrote:
>>
>>>
>>>
>>>
>>> On Thu, Mar 13, 2014 at 6:49 PM, Ankit Agrawal <aaaagrawal at gmail.com>wrote:
>>>
>>>>
>>>> On Wed, Mar 12, 2014 at 5:27 AM, Skipper Seabold <jsseabold at gmail.com>wrote:
>>>>
>>>>> On Tue, Mar 11, 2014 at 6:22 PM, Ankit Agrawal <aaaagrawal at gmail.com>
>>>>> wrote:
>>>>> > Hi everyone,
>>>>> >
>>>>> >          I have created a page on wiki to list the possible tasks
>>>>> that can
>>>>> > go along with the project idea of integrating `pywt` library in
>>>>> scipy.signal
>>>>> > and addition of some related algorithms(denoising and compression
>>>>> using
>>>>> > wavelets) to scikit-image and scipy.signal. Please feel free to
>>>>> suggest or
>>>>> > add any other related task. In the coming 2-3 days, I will go
>>>>> through some
>>>>> > papers and the pywt codebase to come up with better estimates of the
>>>>> time in
>>>>> > which I can complete those tasks. By the end of coming
>>>>> weekend(16th), I hope
>>>>> > to have shortlisted the tasks and the timeline for my GSoC proposal.
>>>>> Thanks.
>>>>> >
>>>>>
>>>>> Hi Ankit,
>>>>>
>>>>> I wrote up a blog post on using pywt for doing wavelet regression a
>>>>> while back. There are some suggestions at the bottom for things I
>>>>> found difficult and could easily be improved
>>>>
>>>>
>>> Would be useful to get more suggestions like this. Because the API is
>>> more or less fixed after one release, ideas that improve that API should be
>>> prioritized I think. So far I've kept compatibility with upstream so that
>>> it would be easy to contribute back, but it's now clear that upstream is
>>> dead.
>>>
>>> Some things that need changing or a closer look:
>>> - the thresholding functions cannot keep their current names. Probably
>>> should be a single function instead of four.
>>> - the tuple of tuples of approximation coefficients returned by
>>> dwt/swt/wavedec functions is ugly. Some container class with a few useful
>>> methods would be nicer.
>>> - the very different approach in the dwt/swt versus the wavelet packets
>>> is quite odd.
>>> - also some renaming is in order: `MODES` is not PEP8 compliant, `qmf`
>>> is already used in scipy.signal, `families` is too generic,
>>> upcoef/downcoef/scal2frq/orthfilt are not very informative.
>>>
>>> Ralf
>>>
>>>
>>>
>>>
>>>>  like making pywt a little
>>>>> more consistently object-oriented to save some keystrokes.
>>>>>
>>>>
>>>> Hi Skipper,
>>>>
>>>>          Great blog post. What are your suggestions for some objects
>>>> that could be introduced? For instance in your blog post example, you hint
>>>> of a wavelet object that holds the coefficient arrays returned from
>>>> `wavedec`, so that it could be passed to threshold functions. If I
>>>> understand your use case correctly, won't this be a bit less generic in
>>>> cases where you want only a subset of coefficient arrays to be thresholded?
>>>>
>>>>
>>>>> Feel free to use any of this example code as well, if you think it
>>>>> could find a home somewhere.
>>>>>
>>>>
>>>> The example could find a home in tutorial section. Thanks.
>>>>
>>>> http://jseabold.net/blog/2012/02/23/wavelet-regression-in-python/
>>>>>
>>>>> Skipper
>>>>> _______________________________________________
>>>>> SciPy-Dev mailing list
>>>>> SciPy-Dev at scipy.org
>>>>> http://mail.scipy.org/mailman/listinfo/scipy-dev
>>>>>
>>>>
>>>>
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>>
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