ConnectionPath with fancy arrow of length zero produces no plot

[eyurtsev]

The following code produces no plot:

%pylab inline
from matplotlib.patches import ConnectionPatch
xy1 = (0.3, 0.3)
xy2 = (0.3, 0.3)
ax = gca()
con = ConnectionPatch(xyA=xy1, xyB=xy2, coordsA="data", coordsB="data",
                      arrowstyle='fancy', # <-- this is ok
                      axesA=ax, axesB=ax)
ax.add_artist(con)

It works fine if I change the arrowstyle to the default.

With arrowstyle='fancy', I get the following warnings:

/usr/local/lib/python2.7/dist-packages/matplotlib/patches.py:2960: RuntimeWarning: divide by zero encountered in double_scalars
ff = d / (dx * dx + dy * dy) ** .5
/usr/local/lib/python2.7/dist-packages/matplotlib/patches.py:2961: RuntimeWarning: invalid value encountered in double_scalars
x2, y2 = x0 - ff * dx, y0 - ff * dy

The problem is probably with FancyArrow:

%pylab inline
from matplotlib.patches import FancyArrow, FancyArrowPatch, Arrow

# Arrow is OKAY
p = Arrow(0.3, 0.3, 0, 0) 
gca().add_patch(p)

# FancyArrow gives a RuntimeWarning about invalid values. (likely division by zero)
p = FancyArrow(0.3, 0.3, 0, 0)
gca().add_patch(p)

running matplotlib 1.4.2

[mdboom]

@leejjoon: I think this might be your area?

[tacaswell]

I suspect that this just needs the expander logic that is scattered else where through out the code (thinking in particular of the hex-bin range logic when min(d) == max(d)).