Pim Schellart wrote:
> Dear Michael,
>
> thank you for the tips.
> The color solution works fine but the logarithmic scale has some issues.
> It is displayed once but I get the following warning:
>
> /Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/matplotlib/axes.py:1091:
> UserWarning: aspect is not supported for Axes with xscale=linear,
> yscale=log
> % (xscale, yscale))
>
> the aspect ratio is also clearly wrong and my polar plot looks like an oval.
> I think this warning is not very accurate since for a polar plot the
> `y' axis means r and this is supposed to be the same in all (real x,y)
> directions.
>
Can you provide a short, standalone script that reproduces this
problem? I don't see it here. What version of matplotlib are you using?
Mike
> Also it does not seem to remember it's state (which may be due to me
> calling ax.clear() to clear the plot when drawing a new batch of
> points) and reverts to lineair.
> I use the Qt Agg backend and performance seems to be ok.
> I would like to fix the axis and not redraw it on every plot (perhaps
> using blitting) if possible.
>
> Kind regards,
>
> Pim Schellart
>
> 2010/5/4 Michael Droettboom <md...@stsci.edu>:
>
>> Pim Schellart wrote:
>>
>>> Hi Everyone,
>>>
>>> I am currently building an interactive display using matplotlib but I
>>> need the following two options.
>>> 1. Setting the r axis of a polar plot to logaritmic scale.
>>>
>>>
>> axis.set_rscale('log')
>>
>>> 2. Setting alpha for each point individually (preferably by giving
>>> alpha an array of the same length as the data containing a value
>>> between zero and one).
>>> Is this currently possible and if not which alternative approach do
>>> you recommend.
>>>
>>>
>> You can't give alpha an array, but you can create an Nx4 RGBA array (which
>> will let you control the color individually, too). For example:
>>
>> r = np.arange(0, 3.0, 0.01)
>> theta = 2*np.pi*r
>> c = np.zeros((len(r), 4))
>> c[:,0:3] = (1, 0, 0) # red
>> c[:,3] = np.arange(0, 1.0, 1.0 / len(r))
>> ax.scatter(theta, r, c=c, lw=0)
>>
>>> The display needs to plot about a thousand points (using scatter at
>>> the moment) roughly updating every second with older points fading
>>> away (lower value of alpha).
>>>
>>>
>> Scatter is pretty heavily optimized in the *Agg backends, but not so much in
>> the others. Make sure you are using Agg and IIRC this level of performance
>> should be possible (depending on machine etc., of course).
>>
>> Mike
>>
>>
>> --
>> Michael Droettboom
>> Science Software Branch
>> Operations and Engineering Division
>> Space Telescope Science Institute
>> Operated by AURA for NASA
>>
>>
>>
--
Michael Droettboom
Science Software Branch
Operations and Engineering Division
Space Telescope Science Institute
Operated by AURA for NASA
------------------------------------------------------------------------------
_______________________________________________
Matplotlib-users mailing list
Matplotlib-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/matplotlib-users
