Re: [Matplotlib-users] fill area between two curves? fill_between?

[<rep...@we...>]

John Hunter: Normally I wouldn't waste bandwith in a mailing-list by sending
neither a question nor an answer, but in this case I feel the urge to thank
you for your support. Your function does exactly what I need and you even
gave a hint on how to implement such functional extensions. On top of that,
the answer came an hour after I sent the question :-)

> All of the matplotlib plot commands create primitive objects
> (lines.Line2D, patches.Rectangle, patches.Polygon, text.Text).  If a
> plot command doesn't suit your needs, you can roll your own by
> creating the right kind of primitive object. [...]

Do I have to dive into the class description at
http://matplotlib.sourceforge.net/classdocs.html to get this informations or
is there a more user-friendly description of the matplotlib internals?

Thanks
Dirk


----- Original Message -----
From: "John Hunter" <jdh...@ac...>
To: <rep...@we...>
Cc: <mat...@li...>
Sent: Tuesday, September 28, 2004 2:15 PM
Subject: Re: [Matplotlib-users] fill area between two curves? fill_between?


> >>>>> "Dirk" ==   <rep...@we...> writes:
>
>     Dirk> I want to fill the area between two curves with a color
>     Dirk> (incl. alpha channel, I use the agg backend). fill() seems
>     Dirk> to fill only the area between the x-axis and one curve - at
>     Dirk> least I found no way for filling only the area between two
>     Dirk> graphs. Is there a way for doing so at all? Or do I have to
>     Dirk> use another graphic library for this kind of fill_between()?
>
> All of the matplotlib plot commands create primitive objects
> (lines.Line2D, patches.Rectangle, patches.Polygon, text.Text).  If a
> plot command doesn't suit your needs, you can roll your own by
> creating the right kind of primitive object.  Here is a fill_between
> implementation
>
> from matplotlib.matlab import *
> from matplotlib.patches import Polygon
>
> def fill_between(ax, x, y1, y2, **kwargs):
>     # add x,y2 in reverse order for proper polygon filling
>     verts = zip(x,y1) + [(x[i], y2[i]) for i in range(len(x)-1,-1,-1)]
>     poly = Polygon(verts, **kwargs)
>     ax.add_patch(poly)
>     ax.autoscale_view()
>     return poly
>
> x = arange(0, 2, 0.01)
> y1 = sin(2*pi*x)
> y2 = sin(4*pi*x) + 2
> ax = gca()
>
> p = fill_between(ax, x, y1, y2, facecolor='g')
> p.set_alpha(0.5)
> show()
>
> Hope this helps,
> JDH
>