Setting right spine position to 'zero' locates spine at +1

Hi all-

I’ve been working on a plot that puts the bottom and right spines at zero (adapting some code from the example at http://matplotlib.org/examples/pylab_examples/spine_placement_demo.html) , and I’ve discovered that setting the position of the right spine to ‘zero’ seems to locate it at x=1.

Is this a bug? Or is there something that I’m missing?

Thanks,

–Chad

Here’s an example that demonstrates the behavior:

import matplotlib.pyplot as plt

f=plt.figure(1)
ax=plt.subplot(111)
ax.spines[‘left’].set_color(‘none’)
ax.spines[‘top’].set_color(‘none’)
ax.spines[‘right’].set_position(‘zero’)
ax.spines[‘bottom’].set_position(‘zero’)

ax.xaxis.set_ticks_position(‘bottom’)
ax.yaxis.set_ticks_position(‘right’)
ax.set_xlim([-2,2])
ax.set_ylim([-2,2])

plt.show()