Re: [matplotlib-devel] [Matplotlib-users] ANN: mpltools 0.1 release

[John H. <jd...@gm...>]

On Wed, Jul 11, 2012 at 10:09 AM, Damon McDougall <dam...@gm...
> wrote:
>
> Well, as Ben said, that error fill plot is neato! It doesn't look too
> complicated, either. I'd be more than happy to port it over later today
> when I get bored of typing up my thesis. It'll probably only take me
> about 30 minutes.
>
> If nobody is opposed to this idea, I'll go ahead and submit a PR this
> evening (British Summer (hah!) Time).
>


While it is a nice graph, I am not sure that the use case is common enough
to justify a new plotting method.  One can get the same result with:


  In [68]: x = np.linspace(0, 2 * np.pi)

  In [69]: y_sin = np.sin(x)

  In [70]: err = np.concatenate([y_sin + 0.2, y_sin[::-1] - 0.2])

  In [71]: plot(x, y_sin)
  Out[71]: [<matplotlib.lines.Line2D object at 0x96959ec>]

  In [72]: fill_between(np.concatenate([x, x[::-1]]), err, facecolor='red',
alpha=0.5)
  Out[72]: <matplotlib.collections.PolyCollection object at 0x962758c>

Admittedly the [::-1] thing is a bit counter-intuitive, but rather than
adding a new plotting method, perhaps we would be better off with a helper
method to create the xs and ys for fill_between

  xs, ys = mlab.pad_line(x, y, 0.2)
  fill_between(xs, ys)

JDH