## Re: [Matplotlib-users] ANN: mpltools 0.1 release

 Re: [Matplotlib-users] ANN: mpltools 0.1 release From: Damon McDougall - 2012-07-12 13:28:21 ```On Wed, Jul 11, 2012 at 08:33:21PM -0400, Tony Yu wrote: > On Wed, Jul 11, 2012 at 2:28 PM, Benjamin Root wrote: > > > > > > > On Wed, Jul 11, 2012 at 11:23 AM, John Hunter wrote: > > > >> > >> > >> On Wed, Jul 11, 2012 at 10:09 AM, Damon McDougall < > >> damon.mcdougall@...> 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]: [] > >> > >> In [72]: fill_between(np.concatenate([x, x[::-1]]), err, > >> facecolor='red', alpha=0.5) > >> Out[72]: > >> > >> 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 > >> > > > > > > I could definitely agree with a pad_line() function. We might want to > > revisit the issue of how much visibility the mlab module should get in the > > documentation (it currently doesn't get much at all). My whole take on > > mlab was that it was a left-over from the days of working around issues in > > NumPy and SciPy and that it was being slowly phased out. As for other > > possible locations, cbook feels like it is more for the devs than for the > > users, and adding it to pyplot would render the whole purpose of creating > > this function as opposed to errorfill moot. > > > > As an additional point about such a pad_line function, it should probably > > be nice to mirror the errorbar() functionality to allow not only a constant > > error, but also a N, Nx1, or 2xN array of +/- error. (note that errorbar() > > for the 2xN array case does -row1 and +row2). > > > > Damon: it sounds like you're volunteering to submit a PR to add this > function ;) > > Here's the relevant bit (which should already handle the cases Ben mentions > above): > > > https://github.com/tonysyu/mpltools/blob/master/mpltools/special/errorfill.py#L54 > > It needs a docstring and a home (pyplot.py?). I kind of think `offset_line` > is more explicit than `pad_line` (both of these are *much* better than my > original `extrema_from_error_input`). > > Cheers, > -Tony > > > > Cheers! > > Ben Root > > > > Woohoo! Something other than my thesis to do! I have one question. It looks like your function `extrema_from_error_input` just adds +/- an error scalar (or array), but in the gallery it looks like the padding is thinner in the areas of the `sin` function where the magnitude of the gradient is larger. Is this the case, or am I missing something? -- Damon McDougall http://damon-is-a-geek.com B2.39 Mathematics Institute University of Warwick Coventry West Midlands CV4 7AL United Kingdom ```