Re: [matplotlib-devel] animation of a fill_between region

[Jacob V. <ja...@cs...>]

Hi Mauricio,
Patch objects are a bit more difficult to work with than line objects,
because unlike line objects are a step removed from the input data supplied
by the user.  There is an example similar to what you want to do here:
http://matplotlib.org/examples/animation/histogram.html

Basically, you need to modify the vertices of the path at each frame.  It
might look something like this:

from matplotlib import animation
import numpy as np
import matplotlib.pyplot as plt

fig, ax = plt.subplots()
ax.set_xlim([0,10000])

x = np.linspace(6000.,7000., 5)
y = np.ones_like(x)

collection = plt.fill_between(x, y)

def animate(i):
    path = collection.get_paths()[0]
    path.vertices[:, 1] *= 0.9

animation.FuncAnimation(fig, animate,
                        frames=25, interval=30)

Take a look at path.vertices to see how they're laid out.
Hope that helps,
   Jake


On Sat, Feb 1, 2014 at 7:44 AM, Mauricio Calvao <moc...@gm...> wrote:

> Hi there,
>
> I have the following simple code to plot a (static)  fill_between region
> in a given plot.
>
>
> import numpy as np
> import matplotlib. pyplot as plt
>
> plt.figure()
> ax=plt.axes()
> ax.set_xlim([0,10000])
>
> x = np.linspace(6000.,7000.)
> y = np.ones(np.shape(x))
>
> plt.fill_between(x,y)
>
>
> I would like now to animate this band (which is a PolyCollection object,
> and not a Line2D one) so that it moves smoothly to the right up together
> with being stretched, that is, to the new x positions: .7200, 8400. I saw
> several animations in the matplotlib homepage, but they only looped over
> line or image objects, not polycollection ones, such as fill_between... Is
> this possible?
>
> In stackoverflow there is this link:
> http://stackoverflow.com/questions/16120801/matplotlib-animate-fill-between-shape,
> which might solve this question but I was not able to understand it fully
> in order to have a simple minmal working example. If that is the right
> direction, I would appreciate immensely if someone could provide such an
> example!
>
> Thanks in advance
>
> --
> #######################################
> Prof. Mauricio Ortiz Calvao
> Federal University of Rio de Janeiro
> Institute of Physics, P O Box 68528
> CEP 21941-972 Rio de Janeiro, RJ
> Brazil
>
> Email: or...@if...
> Phone: (55)(21)25627483
> Homepage: http://www.if.ufrj.br/~orca
> #######################################
>
>
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