Pandas系列-最后x行中的最低值

Question

我试图构建一个函数，将最后10行中的最低值打印到Pandas数据帧的新列中hData.market_数据[“AAPL”]：

    close   volume  open    high    low
2015-11-11  116.110001  45218000    116.370003  117.419998  115.209999
2015-11-12  115.720001  32262600    116.260002  116.820000  115.650002
2015-11-13  112.339996  45164100    115.199997  115.570000  112.269997
2015-11-16  114.180000  37651000    111.379997  114.239998  111.000000
2015-11-17  113.690002  27254000    114.919998  115.050003  113.320000
2015-11-18  117.290001  46163400    115.760002  117.489998  115.500000
2015-11-19  118.779999  42908200    117.639999  119.750000  116.760002
2015-11-20  119.300003  34103500    119.199997  119.919998  118.849998
2015-11-23  117.750000  32266700    119.269997  119.730003  117.339996
2015-11-24  118.879997  42426900    117.330002  119.349998  117.120003

我带着这个来的：

^{pr2}$

但它打印的是从整个系列的最后10行计算出的最小值（而不是通过 系列）。 你能告诉我怎么做吗？在

Answer 1

IIUC然后你想要^{}：

In [93]:
df['lowest_10'] = pd.rolling_min(df['low'],window=3)
df

Out[93]:
                 close    volume        open        high         low  \
2015-11-11  116.110001  45218000  116.370003  117.419998  115.209999   
2015-11-12  115.720001  32262600  116.260002  116.820000  115.650002   
2015-11-13  112.339996  45164100  115.199997  115.570000  112.269997   
2015-11-16  114.180000  37651000  111.379997  114.239998  111.000000   
2015-11-17  113.690002  27254000  114.919998  115.050003  113.320000   
2015-11-18  117.290001  46163400  115.760002  117.489998  115.500000   
2015-11-19  118.779999  42908200  117.639999  119.750000  116.760002   
2015-11-20  119.300003  34103500  119.199997  119.919998  118.849998   
2015-11-23  117.750000  32266700  119.269997  119.730003  117.339996   
2015-11-24  118.879997  42426900  117.330002  119.349998  117.120003   

             lowest_10  
2015-11-11         NaN  
2015-11-12         NaN  
2015-11-13  112.269997  
2015-11-16  111.000000  
2015-11-17  111.000000  
2015-11-18  111.000000  
2015-11-19  113.320000  
2015-11-20  115.500000  
2015-11-23  116.760002  
2015-11-24  117.120003  

所以我认为以下几点应该对你有用：

^{pr2}$