Say I have drawn a plot and now I want to make an
> annotation on the top of the plot outside the axis. In my
> case I want to put a filled triangle up there in a certain
> location. I am using a polygon - patch to make the figure.
> How does one do this? I have tried turning the clipping off
> but to no avail - I can put my triangle anywhere within the
> axis but if it is outside it disappears. In the manual
> there is an example for placing text outside the axis but
> not patches.
The problem you are encountering is that the Axes will automatically
set the clipbox when you call add_patch, so you need to make the call
to turn off clipping *after* adding it to the axes
from pylab import figure, show
from matplotlib.patches import RegularPolygon
fig = figure()
ax = fig.add_subplot(111)
# above the yaxis and centered on xaxis; Axes coords
tri = RegularPolygon((0.5, 1.05), 3, radius=0.2, transform=ax.transAxes)
# adding the patch to the axes automatically sets the clipbox
ax.add_patch(tri)
# so you need to turn it off after adding it
tri.set_clip_on(False)
show()
You can also add patches and lines directly to the Figure instance, as
follows, but these are drawn before the Axes and so are behind them
from pylab import figure, show
from matplotlib.patches import RegularPolygon
fig = figure()
ax = fig.add_axes([0.1,0.1, 0.8, 0.6])
# Figure coords
tri = RegularPolygon((0.5, 0.8), 3, radius=0.2, transform=fig.transFigure)
fig.patches.append(tri)
show()
If there is a need to customize this further, let me know. Eg, we
could move the drawing call for the lines and patches below the Axes
draw so they come out on top.
JDH