Re: [Matplotlib-users] legend on a plot with broken_barh()

[Paul H. <pmh...@gm...>]

[Forgot to reply-all, sorry for the dup, gsal]

On Fri, Jan 4, 2013 at 1:22 PM, gsal <sal...@gm...> wrote:

> can you provide an example? The reference help is only two lines!
>
> Given:
> [code]
> import numpy as np
> import matplotlib.pyplot as plt
>
> fig = plt.figure()
> ax = fig.add_subplot(111)
> ax.broken_barh([ (110, 30), (150, 10) ] , (10, 9), facecolors='b',
> label='barh')
>
> ax.set_xlim((0,200))
> ax.set_ylim((0,50))
>
> ax.legend()
>
> plt.show()
> [/code]
>
> How do I import what in order to, say, create a plot
> "plot([0.0],[0.0],'bs')" so that I can at least plot a marker of the same
> color as my broken_barh so that when the legend is added, the correct icon
> precedes the label?
>
> I tried adding
>
> pp = plt.plot([80],[40],'bs', label='proxy artist')
>
> to the previous program, right before the legend command, but it actually
> plots the marker, too.
>
> Is there a way to import "plot" or "Line2D" or something so that I can
> produce an artist that is NOT related to the plot and, hence, not plotted?
> (is that what "proxy artist" means?).
>

Yes. Proxy artists are created in memory but never added to the axes
object. Here's an expanded version of the example:

import matplotlib.patches as mpatch
import matplotlib.pyplot as plt
fig, ax = plt.subplots()
patch = mpatch.Rectangle((0, 0), 1, 1, fc="r")
ax.legend([patch], ["Proxy artist"])
plt.show()

So for your example, I'd do the following:

import numpy as np
import matplotlib.pyplot as plt
import matplotlib.patches as mpatch
fig = plt.figure()
ax = fig.add_subplot(111)
ax.broken_barh([ (110, 30), (150, 10) ] , (10, 9), facecolors='b',
label='barh')
ax.set_xlim((0,200))
ax.set_ylim((0,50))
fakeredbar = mpatch.Rectangle((0, 0), 1, 1, fc="r")
fakebluebar = mpatch.Rectangle((0, 0), 1, 1, fc="b")
ax.legend([fakeredbar, fakebluebar], ['Red Data', 'Blue Data'])
plt.show()

Now to me, it seems very strange that broken_barh doesn't generate any
items in a legend. Not sure why that is but it seems like a bug.

Hope that helps,
-paul