@leejjoon: I received this private e-mail from Rolf Barinka, and I think you may be the most appropriate person to address it.

Hello Michael Droettboom

I found a bug in matplotlib 1.1.1.
And I offer a bugfix.

I am not part of the development team and don't want to be.
So I offer my bugfix to you, because i saw you involved with the bug.

I used matplotlib 1.1.0 and saw this exception:
a long traceback culminating in
/usr/lib64/python2.7/site-packages/matplotlib/bezier.py",
line 129, in find_bezier_t_intersecting_with_closedpath
     raise ValueError("the segment does not seemed to intersect with the path")

I googled and found the "Pull Request #566" for matplotlib, which seemed to solve
the problem:
"fix fancy-style annotation causing an exception when..."
<https://github.com/matplotlib/matplotlib/pull/566>

I installed matplotlib 1.1.1 incl. #566.
The bug stayed alive.

In #566 a new exception NonIntersectingPathException was created.
This exception was caught in patches.py: Fancy.transmute().

But in my case the exception occurred in patches.py: Simple.transmute().
So I catch it there and do something to work around.
I am not sure that my workaround is okay for all cases.
It works for my application.

Please consider my bugfix:

41# diff /home/bai/software/matplotlib-1.1.1/lib/matplotlib/patches.py /usr/lib64/python2.7/site-packages/matplotlib/patches.py
3404,3405c3404,3409
<             arrow_out, arrow_in = \
<                        split_bezier_intersecting_with_closedpath(arrow_path,
---

            from bezier import NonIntersectingPathException

          try:
               arrow_out, arrow_in = \
                          split_bezier_intersecting_with_closedpath(arrow_path,
3407a3412,3418
            except NonIntersectingPathException:
                arrow_out = arrow_path
                dx, dy = x2 - x1, y2 - y1
                ff = head_length/(dx*dx+dy*dy)**.5
                x0, y0 = x2 - ff*dx, y2 - ff*dy
                arrow_path = [(x0, y0), (x1, y1), (x2, y2)]
                arrow_in = arrow_path

And please tell me what you think about it.

Michael, can you contact Rolf Barinka and ask if he/she can send an example script that reproduces this error?

@leejjoon: Hello, this is Rolf Barinka.

The code that brings the exception is part of a complex application, and it is hard to seperate.

I put some prints into patches.py and bezier.py:

    def transmute(self, path, mutation_size, linewidth):
        ...
    try:
           ...
        except NonIntersectingPathException:
    print 'NonIntersectingPathException'
            ....

def find_bezier_t_intersecting_with_closedpath(bezier_point_at_t, inside_closedpath,
t0=0., t1=1., tolerence=0.01):
...
if not xor(start_inside, end_inside):
print 't0=', t0, ' t1=', t1, ' tol=', tolerence
print 'start=', start, ' end=', end
print 'start_inside=', start_inside, ' end_inside=', end_inside
raise NonIntersectingPathException("the segment does not seemed to intersect with the path")

Now some parts of my script, that raise the exception:

def pol2kar(w, r):
"polar [grad,mm] --> karthesisch [x,y]"
if type(w) is list:
phi = [ a / fakt for a in w ]
else:
phi = w / fakt
return (r * np.cos(phi), r * np.sin(phi))

def pfeil(ax, r,v, col, xM=0, yM=0):
"""Pfeil malen
PolKoo color"""
print 'r=', r, ' v=', v
(xp, yp) = pol2kar(r, v)
print 'xM,yM=', xM, yM
x = [ a + xM for a in xp ]; y = [ b + yM for b in yp ]
rad = 0.0680529
cs = 'arc3, rad=%g' % rad
d = dict(arrowstyle='simple', connectionstyle=cs, alpha=0.2, fc=col, ec='none')
print 'x=', x, ' y=', y
print 'd=', d
ax.annotate('', xy=(x[2], y[2]), xytext=(x[0], y[0]), arrowprops=d)

r = [220, 222, 226]
v = [-322.455, -322.455, -320.189]

we need an Axes object "ax" and a color "col"

this brings the exception:

pfeil(ax, r, v, col)

This was the output:
r= [220, 222, 226] v= [-322.455, -322.455, -320.189]
xM,yM= 0 0
x= [247.01486090593005, 239.63076469931315, 222.42196897889596] y= [207.270078681473, 215.76450967344562, 230.32469133063231]
d= {'connectionstyle': 'arc3, rad=0.0680529', 'alpha': 0.2, 'fc': '#DD0000', 'arrowstyle': 'simple', 'ec': 'none'}
t0= 0.0 t1= 1.0 tol= 0.01
start= (396.80739712418909, 350.43678238448041) end= (402.37062135854825, 346.84973645969643)
start_inside= True end_inside= True
NonIntersectingPathException

Rolf, please test with my proposed change above. Let us know if things work okay in your side.

Hello

Yes, things work okay for me.
Your arrow looks like mine.

Jae-Joon Lee schrieb Folgendes am 2012-08-21 20:58:

Rolf, please test with my proposed change above. Let us know if things work okay in your side.

—
Reply to this email directly or view it on GitHub #566 (comment).

Freundliche Grüße
Rolf Barinka
Abt: AHPS
Fon: 5713