有迴歸線的Seaborn barplot

Question

有沒有方法可以將回歸線添加到x軸包含pandas的seaborn中的barplot中。時間戳？

例如，在下面的條形圖中覆蓋趨勢線。在尋找最有效的方式做到這一點：

seaborn.set(style="white", context="talk") 
a = pandas.DataFrame.from_dict({'Attendees': {pandas.Timestamp('2016-12-01'): 10, 
    pandas.Timestamp('2017-01-01'): 12, 
    pandas.Timestamp('2017-02-01'): 15, 
    pandas.Timestamp('2017-03-01'): 16, 
    pandas.Timestamp('2017-04-01'): 20}}) 
ax = seaborn.barplot(data=a, x=a.index, y=a.Attendees, color='lightblue',) 
seaborn.despine(offset=10, trim=False) 
ax.set_ylabel("") 
ax.set_xticklabels(['Dec', 'Jan','Feb','Mar','Apr']) 
plt.show() 

Answer 1

Seaborn barplots是絕對的地塊。分類圖不能直接用於迴歸，因爲數值不適合。然而，通常的matplotlib條形圖卻使用數字數據。

一個選項是在同一個圖中繪製matplotlib barplot和seaborn regplot。

import numpy as np; np.random.seed(1) 
import seaborn.apionly as sns 
import matplotlib.pyplot as plt 

x = np.linspace(5,9,13) 
y = np.cumsum(np.random.rand(len(x))) 

fig, ax = plt.subplots() 

ax.bar(x,y, width=0.1, color="lightblue", zorder=0) 
sns.regplot(x=x, y=y, ax=ax) 
ax.set_ylim(0, None) 
plt.show() 

由於seaborn的barplot使用從0整數爲indizes的條數，還可以使用那些indizes對seaborn條形圖頂部的迴歸圖。

import numpy as np 
import seaborn.apionly as sns 
import matplotlib.pyplot as plt 
import pandas 

sns.set(style="white", context="talk") 
a = pandas.DataFrame.from_dict({'Attendees': {pandas.Timestamp('2016-12-01'): 10, 
    pandas.Timestamp('2017-01-01'): 12, 
    pandas.Timestamp('2017-02-01'): 15, 
    pandas.Timestamp('2017-03-01'): 16, 
    pandas.Timestamp('2017-04-01'): 20}}) 
ax = sns.barplot(data=a, x=a.index, y=a.Attendees, color='lightblue') 
# put bars in background: 
for c in ax.patches: 
    c.set_zorder(0) 
# plot regplot with numbers 0,..,len(a) as x value 
sns.regplot(x=np.arange(0,len(a)), y=a.Attendees, ax=ax) 
sns.despine(offset=10, trim=False) 
ax.set_ylabel("") 
ax.set_xticklabels(['Dec', 'Jan','Feb','Mar','Apr']) 
plt.show()