如何按月为日期时间创建 bins 并根据它绘制值?

how to create bins for date time by month and plot value counts on it?

我有 8000 天时间戳类型的列:

2013-09-06 00:00:00

我想创建条形图,但按月分组,也许晚些年。现在我有太多的值(天),它们都变成了情节上的一个黑点:

basic_data['opendate'].value_counts().plot(kind='barh')

我试过这个:

by_month = basic_data['opendate].groupby(pd.Grouper(key='date', freq='M')).sum() #maybe count? 

如何在直方图上绘制和创建 bins?

使用Grouper with key parameter by opendate column and then GroupBy.size:

rng = pd.date_range('2017-04-03', periods=100)
basic_data = pd.DataFrame({'opendate': rng, 'a': range(100)})  
print (basic_data)
     opendate   a
0  2017-04-03   0
1  2017-04-04   1
2  2017-04-05   2
3  2017-04-06   3
4  2017-04-07   4
..        ...  ..
95 2017-07-07  95
96 2017-07-08  96
97 2017-07-09  97
98 2017-07-10  98
99 2017-07-11  99

[100 rows x 2 columns]

basic_data.groupby(pd.Grouper(key='opendate', freq='M')).size().plot(kind='barh')