Re: [matplotlib-devel] Pull request

[Pierre H. <pie...@cr...>]

Hello,


Now that that PR #2522 is merged, I don't know how much futher
commenting is useful, but I think there are two API details that I feel
could be better :

1) API dissymetry

The new pyplot/axes API is now:

 * 1 function *spectgram* now uses a mode argument to tune this behavior :

*mode*: [ 'default' | 'psd' | 'magnitude' | 'angle' | 'phase' ]
             What sort of spectrum to use.  Default is 'psd'. which takes
             the power spectral density.  'complex' returns the
complex-valued
             frequency spectrum.  'magnitude' returns the magnitude
spectrum.
            'angle' returns the phase spectrum without unwrapping.  'phase'
             returns the phase spectrum with unwrapping.

* 3 new functions *phase_spectrum, angle_spectrum, magnitude_spectrum*
which complement the exising psd/csd

-> I think this contributes to overcrowding axes/pyplot API. I like much
better what is done with specgram so I would propose to add just one new
function, for example *spectrum*(...mode='magnitude/angle/phase'). Using
the same /mode /keyword as for specgram would increase the coherence of
the API.



2) default NFFT value being hidden from views

used to be def specgram(x, NFFT=256,  Fs=2, ...
now is     def specgram(x, NFFT=None, Fs=None

I think that NFFT is an important parameter of the spectrum computation.
It should not be /hidden from the immediate view of the user/. The fact
it is set to 256 is an arbitrary choice and I think it even teaches
something to the user (if he doesn't know what it is). Such a fixed
value is an "invitation to change it". Now with NFFT=None, it is more
likely to imply "a good choice was made for you", which is not true
(because there is no such good choice for all datasets).



best,
Pierre