Hello,
On Sat, Nov 15, 2008 at 11:06 AM, Ronan Paixão <[EMAIL PROTECTED]> wrote:
>
> Em Sex, 2008-11-14 às 16:22 -0200, Ronan Paixão escreveu:
>> I recently thought about implementing more functions used by non-math
>> people (I'm an Electronic Engineering student).
>>
>> I started by trying to make a Bode plot, but after a lot of digging to
>> find how to make subplots and how to use logarithmic scale in plot(), I
>> found that if applying that kind of scale can turn plot() unusable.
>>
>> The first problem is that the adaptive choosing of points just considers
>> linear scale, so the points get too much spaced apart in the beginning
>> of the plot and too close in the end.
>>
>> The second problem relates to the axis, which, for the same reason,
>> isn't located right.
>>
>> to test it, one can try:
>>
>> p=plot(x,marker='.')
>> f=pylab.figure()
>> f.gca().set_xscale('log')
>> p.save(figure=f)
>>
>> So, I intend to implement the changes in plot() to support it.
>> For that, I ask YOU (uncle sam pointing finger) sage gurus how to better
>> implement that: would it be better to try check if the user used a
>> custom figure() with different axis or would it be better to add another
>> kwarg like log="xy" where "x" would make the x axis logarithmic and "y"
>> likewise for the y axis, avoiding the need for the user to deal with
>> matplotlib's figure()?
>>
After thinking about this (and the plotting code in general), I think
our best bet is to scrap the custom axes code written in
sage/plot/axes.py and to let matplotlib handle axes, ticks, etc.
They've thought about and worked on this problem and have developed a
fairly robust solution. Most of the axes code hasn't been touched in
over 2 years despite complaints ( see
http://groups.google.com/group/sage-devel/browse_thread/thread/394b2fc202757335/9441b88e109573ee?lnk=gst&q=ticks#9441b88e109573ee
). If we want custom axes, then we should do so by properly
subclassing matplotlibs Axes class.
Additionally, I think the Graphics wrapper should not be nearly as
heavy as it is. In particular, there's no way to get at and modify
the matplotlib subplot object. For example, I have some preliminary
code that would let one do this:
sage: p = plot(e^x, 1, 5)
sage: p.subplot.set_xlabel('Mike')
<matplotlib.text.Text object at 0x46b8350>
sage: p.subplot.set_title('A plot')
<matplotlib.text.Text object at 0x46badd0>
sage: p.subplot.set_ylabel("Sage")
<matplotlib.text.Text object at 0x46ba090>
sage: p.save('plot1.png')
sage: p.subplot.set_yscale('log')
sage: p.save('plot2.png')
to produce the following images:
http://sage.math.washington.edu/home/mhansen/plot1.png
http://sage.math.washington.edu/home/mhansen/plot2.png
While this would mean being more closely tied to matplotlib as a
backed, I think the benefits are worth it. I don't envision anybody
working on another backend for Graphics anytime in the near future.
--Mike
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