绘制阶梯直方图而不用底线关闭多边形

Question

如何删除关闭阶梯直方图路径的底线？

import numpy as np

import matplotlib.pyplot as plt

mu, sigma = 100, 15

x = mu + sigma * np.random.randn(10000)

fig = plt.figure()

ax = fig.add_subplot(111)

n, bins, patches = ax.hist(x, 50, normed=1, histtype='step')

plt.ylim(-.005, plt.ylim()[1])

plt.show()