Matplotlib堆叠直方图的facecolor kwarg

我无法控制使用Matplotlib的hist函数和stacked=True绘制的直方图的颜色和线条样式.对于单个非堆叠直方图，我没有问题:

I am having trouble controlling the color and linestyle of histogram plotted using Matplotlib's hist function with stacked=True. For a single non-stacked histogram, I have no trouble:

import pylab as P

mu, sigma = 200, 25
x0 = mu + sigma*P.randn(10000)

n, bins, patches = P.hist(
    x0, 20,
    histtype='stepfilled',
    facecolor='lightblue'
    )

但是，当我引入其他直方图时，

However, when I introduce additional histograms,

import pylab as P

mu, sigma = 200, 25
x0 = mu + sigma*P.randn(10000)
x1 = mu + sigma*P.randn(7000)
x2 = mu + sigma*P.randn(3000)

n, bins, patches = P.hist(
    [x0,x1,x2], 20,
    histtype='stepfilled',
    stacked=True,
    facecolor=['lightblue','lightgreen','crimson']
    )

它会引发以下错误:

ValueError: to_rgba: Invalid rgba arg "['lightblue', 'lightgreen', 'crimson']"
could not convert string to float: lightblue

使用color=['lightblue', 'lightgreen', 'crimson']选项确实可以，但是我想分别控制填充和线条颜色，同时能够使用命名的Matplotlib颜色.我正在使用Matplotlib的1.2.1版本.

Using the color=['lightblue', 'lightgreen', 'crimson'] option does work, but I would like to have direct control of the fill and line colors separately while being able to use the named Matplotlib colors. I am using version 1.2.1 of Matplotlib.