Python 3.x 如何停止在数据透视表中按字母顺序排列月份

如何停止将csv中按时间顺序排列的数据转换为按字母顺序排列的数据（如我当前的绘图）。这是我正在使用的代码：

import seaborn as sns

df = pd.read_csv("C:/Users/Paul/Desktop/calendar.csv")

df2 = df.pivot("Month", "Year", "hPM2.5")

ax = sns.heatmap(df2, annot=True, fmt="d")

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我认为您可以使用以下命令：

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定为约会时间？谢谢，这对我来说是解决问题的一种方法。

import pandas as pd
import seaborn as sns

df = pd.DataFrame({'Month':['January','February','September'],
                   'Year':[2015,2015,2016],
                   'hPM2.5':[7,8,9]})

print (df)
       Month  Year  hPM2.5
0    January  2015       7
1   February  2015       8
2  September  2016       9


cats = ['January','February','March','April','May','June',
        'July','August','September','October','November','December']
df['Month'] = df['Month'].astype('category', 
                                  ordered=True,
                                  categories=cats)

df2 = df.pivot("Month", "Year", "hPM2.5")
sns.heatmap(df2, annot=True)