[SciPy-Dev] Proposed API change for some functions in scipy.signal

[Warren Weckesser]

On Thu, Aug 31, 2017 at 6:13 AM, Gael Varoquaux <
gael.varoquaux at normalesup.org> wrote:

> Hi Warren,
>
> Good to see that you are working on improving scipy.signal API. I have
> not strong opinion on the changes that you propose. I am really not an
> expert in DSP. I do find scipy.signal difficult to work with.
>
> While we are at it: is there a reason that scipy.signal.spline_filter
> only support 2D arrays? I naively thought that it would be good
> functionality to have on 1D signals.
>
>

Sorry, I don't know the reason for that.

Warren


Gaël
>
> On Thu, Aug 31, 2017 at 01:22:26AM -0400, Warren Weckesser wrote:
> > I've been using quite a few of the functions in scipy.signal recently,
> and I've
> > been reminded of some of the quirks of the API. I have submitted a pull
> request
> > to clean up one of those quirks.
>
> > In the new pull request, I have added the argument 'fs' (the sampling
> > frequency) to the following functions:  firwin, firwin2, firls, and
> remez.  For
> > firwin, firwin2 and firls, the new argument replaces 'nyq', and for
> remez, it
> > replaces 'Hz'.  This makes these functions consistent with the other
> functions
> > in which the sampling frequency is specified using 'fs': periodogram,
> welch,
> > csd, coherence, spectrogram, stft, and istft. 'fs', or in LaTeX, $f_s$,
> is
> > common notation for the sampling frequency in the DSP literature.
>
> > In the pull request, the old argument is given a "soft" deprecation.
> That means
> > the docstring says the argument is deprecated, but code to actually
> generate a
> > DeprecationWarning has not been added yet.  I'm fine with adding that
> now, but
> > some might prefer a relatively long and soft transition for these
> changes.
> > (Personally, I don't mind if they hang around for a while, but they
> should be
> > gone by 2.0. :)
>
> > I haven't changed the default value of the sampling frequency.  For the
> FIR
> > filter design functions firls, firwin and firwin2, the default is nyq=1.0
> > (equivalent to fs=2), while for remez the default is Hz=1 (i.e. fs=1).
> The
> > functions that currently already use 'fs' all have the default fs=1.
> Changing
> > the default for the FIR design functions would be a much more disruptive
> > change.
>
> > Comments here or on the pull request are welcome.
>
> > P.S. I can see future pull requests in which 'fs' is added to functions
> that
> > currently don't have an argument to specify the sampling frequency.  I'm
> > looking at you, freqz.
>
>
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>
>
> --
>     Gael Varoquaux
>     Researcher, INRIA Parietal
>     NeuroSpin/CEA Saclay , Bat 145, 91191 Gif-sur-Yvette France
>     Phone:  ++ 33-1-69-08-79-68
>     http://gael-varoquaux.info            http://twitter.com/GaelVaroquaux
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