Re: [Matplotlib-users] Using Proxy Artist to make legend

On Thu, Jan 26, 2012 at 8:20 AM, Sabine van der Linden <in...@sb...>wrote:

> Hello,
>
> I have made a plot with a fill_between part, which does not show up in the
> legend. I have read that I have to use a proxy artist for this, but I have
> no
> clue where to place this, and how.. The fill between works fine, it's just
> the
> legend that is not really cooperating ;)
>
> import matplotlib.pyplot as plt
>
> plt.plot(dbx, gemlist)
> plt.title('Reekslengte '+str(i))
> plt.xlabel('signaal-ruisverhouding ingangssignaal (dB)')
> plt.ylabel('signaal-ruisverhouding uitgangssignaal (dB)')
> plt.xlim(-36, 22)
>
> plt.fill_between(dbx, boven, onder, color='b', alpha=0.1)
> plt.legend(loc=4)
> plt.show()
>
> Tnx in advance :)
>
> Sabine
>
>
I have a convenience function (copied below) in my python path that I like
to use for this purpose.

Hope that helps,
-Tony

#~~~~

def fill_between(x, y1, y2=0, ax=None, **kwargs):
    """Plot filled region between `y1` and `y2`.

    This function works exactly the same as matplotlib's fill_between,
except
    that it also plots a proxy artist (specifically, a rectangle of 0 size)
    so that it can be added it appears on a legend.
    """
    ax = ax if ax is not None else plt.gca()
    ax.fill_between(x, y1, y2, **kwargs)
    p = plt.Rectangle((0, 0), 0, 0, **kwargs)
    ax.add_patch(p)
    return p