4
比方说,我有一个分类变量和值时间序列数据帧:在大熊猫的兴趣行之前和之后选择行
In [4]: df = pd.DataFrame(data={'category': np.random.choice(['A', 'B', 'C', 'D'], 11), 'value': np.random.rand(11)}, index=pd.date_range('2015-04-20','2015-04-30'))
In [5]: df
Out[5]:
category value
2015-04-20 D 0.220804
2015-04-21 A 0.992445
2015-04-22 A 0.743648
2015-04-23 B 0.337535
2015-04-24 B 0.747340
2015-04-25 B 0.839823
2015-04-26 D 0.292628
2015-04-27 D 0.906340
2015-04-28 B 0.244044
2015-04-29 A 0.070764
2015-04-30 D 0.132221
如果我感兴趣的是与A类行,过滤分离他们是微不足道的。但如果我对类别A之前的n行感兴趣呢?如果n = 2,我想看到的东西,如:
In [5]: df[some boolean indexing]
Out[5]:
category value
2015-04-20 D 0.220804
2015-04-21 A 0.992445
2015-04-22 A 0.743648
2015-04-27 D 0.906340
2015-04-28 B 0.244044
2015-04-29 A 0.070764
同样,如果我感兴趣的n行各地 A类的?再次如果n = 2,我想看到这个:
In [5]: df[some other boolean indexing]
Out[5]:
category value
2015-04-20 D 0.220804
2015-04-21 A 0.992445
2015-04-22 A 0.743648
2015-04-23 B 0.337535
2015-04-24 B 0.747340
2015-04-27 D 0.906340
2015-04-28 B 0.244044
2015-04-29 A 0.070764
2015-04-30 D 0.132221
谢谢!
你可能会有所帮助:http://stackoverflow.com/questions/28837633/pandas-get-position-of-a-given-指数在非数据帧 –