This a a bug related to stacked xy-plots example,
matplotlib seems to be inserting a vertex at (0,0) into the data set.
The following example is based on the poly3d_demo script linked above. If we change the data set so that the data doesn't include a point at x=0, for example change line 12 from,
xs = np.arange(0, 10, 0.4)
xs = np.arange(5, 10, 0.4)
A erroneous line is drawn from the data set to the (0,0) point.
The following script produces the result(s) below, using matplotlib 1.3.0.
When the x-axis is changed to only include the range of the data set the result look even worse,
from mpl_toolkits.mplot3d import Axes3D
from matplotlib.collections import PolyCollection
from matplotlib.colors import colorConverter
import matplotlib.pyplot as plt
import numpy as np
fig = plt.figure()
ax = fig.gca(projection='3d')
cc = lambda arg: colorConverter.to_rgba(arg, alpha=0.6)
xs = np.arange(5, 10, 0.4) # The data x-range has been changed to run between 5--10
verts = 
zs = [0.0, 1.0, 2.0, 3.0]
for z in zs:
ys = np.random.rand(len(xs))
ys, ys[-1] = 0, 0
poly = PolyCollection(verts, facecolors = [cc('r'), cc('g'), cc('b'),
ax.add_collection3d(poly, zs=zs, zdir='y')
ax.set_xlim3d(5, 10) # This has been changed to 5 to adjust the axis range to the data
@WeatherGod: any thoughts?
related to http://stackoverflow.com/questions/16305256/couldnt-remove-origin-point-in-matplotlib-polycollection which generated issue #2045
closed by #3239