Seaborn / Matplotlib：如何在FacetGrid中访问行值？

Question

我正试图在Seaborn FacetGrid中遮蔽两条线之间的区域。 fill_between方法会执行此操作，但我需要访问每个子图中每行的值以将其传入。

这是我的代码：

import pandas as pd
import matplotlib.pyplot as plt
import seaborn as sns

data = [{'Change': 0.0,  'Language': 'Algonquin',  'Type': 'Mother tongue',  'Year': '2011'}, {'Change': 0.0,  'Language': 'Algonquin',  'Type': 'Spoken at home',  'Year': '2011'}, {'Change': -21.32,  'Language': 'Algonquin',  'Type': 'Mother tongue',  'Year': '2016'}, {'Change': -34.84,  'Language': 'Algonquin',  'Type': 'Spoken at home',  'Year': '2016'}, {'Change': 0.0,  'Language': 'Atikamekw',  'Type': 'Mother tongue',  'Year': '2011'}, {'Change': 0.0,  'Language': 'Atikamekw',  'Type': 'Spoken at home',  'Year': '2011'}, {'Change': 5.41,  'Language': 'Atikamekw',  'Type': 'Mother tongue',  'Year': '2016'}, {'Change': 19.15,  'Language': 'Atikamekw',  'Type': 'Spoken at home',  'Year': '2016'}, {'Change': 0.0,  'Language': 'Blackfoot',  'Type': 'Mother tongue',  'Year': '2011'}, {'Change': 0.0,  'Language': 'Blackfoot',  'Type': 'Spoken at home',  'Year': '2011'}, {'Change': -1.4,  'Language': 'Blackfoot',  'Type': 'Mother tongue',  'Year': '2016'}, {'Change': 61.42,  'Language': 'Blackfoot',  'Type': 'Spoken at home',  'Year': '2016'}, {'Change': 0.0,  'Language': 'Carrier',  'Type': 'Mother tongue',  'Year': '2011'}, {'Change': 0.0,  'Language': 'Carrier',  'Type': 'Spoken at home',  'Year': '2011'}, {'Change': -20.38,  'Language': 'Carrier',  'Type': 'Mother tongue',  'Year': '2016'}, {'Change': -18.91,  'Language': 'Carrier',  'Type': 'Spoken at home',  'Year': '2016'}, {'Change': 0.0,  'Language': 'Chilcotin',  'Type': 'Mother tongue',  'Year': '2011'}, {'Change': 0.0,  'Language': 'Chilcotin',  'Type': 'Spoken at home',  'Year': '2011'}, {'Change': -13.82,  'Language': 'Chilcotin',  'Type': 'Mother tongue',  'Year': '2016'}, {'Change': 7.41,  'Language': 'Chilcotin',  'Type': 'Spoken at home',  'Year': '2016'}, {'Change': 0.0,  'Language': 'Cree languages',  'Type': 'Mother tongue',  'Year': '2011'}, {'Change': 0.0,  'Language': 'Cree languages',  'Type': 'Spoken at home',  'Year': '2011'}, {'Change': -11.52,  'Language': 'Cree languages',  'Type': 'Mother tongue',  'Year': '2016'}, {'Change': 6.57,  'Language': 'Cree languages',  'Type': 'Spoken at home',  'Year': '2016'}]

langs = pd.DataFrame(data)
g = sns.FacetGrid(langs, col='Language', hue='Type', col_wrap = 4, size=2)
g.map(plt.plot, 'Year', 'Change').set_titles('{col_name}')
g.set(xticks=[2011, 2016], yticks = [-40, 0, 70] )

这会生成如下图表：

现在我如何访问每一行的值？我猜g.axes的内容，但文档中没有任何内容可以帮助。

Answer 1

FacetGrid的平面轴数组然后通过ax.lines获取轴对象的所有线。使用get_xdata, get_ydata调用来迭代这些行来请求行的数据，而不是使用这些数据。 示例代码：

...
for ax in g.axes.flat:
    print (ax.lines)
    for line in ax.lines:
        print (line.get_xdata())
        print (line.get_ydata())

输出您的代码数据：

[<matplotlib.lines.Line2D object at 0x10c5facc0>, <matplotlib.lines.Line2D object at 0x10c5fa940>]
['2011' '2016']
[  0.   -21.32]
['2011' '2016']
[  0.   -34.84]
[<matplotlib.lines.Line2D object at 0x10c39a160>, <matplotlib.lines.Line2D object at 0x10c5a4828>]
['2011' '2016']
[ 0.    5.41]
['2011' '2016']
[  0.    19.15]
[<matplotlib.lines.Line2D object at 0x10c5ff6d8>, <matplotlib.lines.Line2D object at 0x10c67c630>]
['2011' '2016']
[ 0.  -1.4]
['2011' '2016']
[  0.    61.42]
[<matplotlib.lines.Line2D object at 0x10c637358>, <matplotlib.lines.Line2D object at 0x10c65ada0>]
['2011' '2016']
[  0.   -20.38]
['2011' '2016']
[  0.   -18.91]
[<matplotlib.lines.Line2D object at 0x10c613668>, <matplotlib.lines.Line2D object at 0x10c6134e0>]
['2011' '2016']
[  0.   -13.82]
['2011' '2016']
[ 0.    7.41]
[<matplotlib.lines.Line2D object at 0x10c5ffd30>, <matplotlib.lines.Line2D object at 0x10c4f5dd8>]
['2011' '2016']
[  0.   -11.52]
['2011' '2016']
[ 0.    6.57]

Answer 2

在@Serenity's上进行扩展。使用行信息get_xdata, get_ydata，您可以使用fill_between之类的

g = sns.FacetGrid(langs, col='Language', hue='Type', col_wrap=4, size=3)
g.map(plt.plot, 'Year', 'Change').set_titles('{col_name}')
g.set(xticks=[2011, 2016], yticks = [-40, 0, 70] )
for ax in g.axes.flat:
    ax.fill_between(ax.lines[0].get_xdata().astype(int),
                    ax.lines[0].get_ydata(0), ax.lines[1].get_ydata(),
                    facecolor='#ffdec1')