Pandas总和重复的指数和总和

Question

我有一个按日期索引的数据框

transactions_ind
Out[25]: 
                   Ticker     Transaction  Number_of_units      Price
Date                                                                 
2012-10-11  ROG VX Equity             Buy            12000  182.00000
2012-10-16  ROG VX Equity            Sell            -5000  184.70000
2012-11-16  ROG VX Equity            Sell            -5000  175.51580
2012-12-07  ROG VX Equity             Buy             5000  184.90000
2012-12-11  ROG VX Equity            Sell            -3000  188.50000
2012-12-11  ROG VX Equity  Reversal: Sell             3000  188.50000
2012-12-11  ROG VX Equity            Sell            -3000  188.50000
2012-12-11  ROG VX Equity  Reversal: Sell             3000  188.50000
2012-12-11  ROG VX Equity            Sell            -3000  188.50000
2012-12-20  ROG VX Equity            Sell            -5000  185.80000

我想总结重复的索引值(2012-12-11),但仅限于"Number_of_units"列.

transactions_ind
Out[25]: 
                   Ticker     Transaction  Number_of_units      Price
Date                                                                 
2012-10-11  ROG VX Equity             Buy            12000  182.00000
2012-10-16  ROG VX Equity            Sell            -5000  184.70000
2012-11-16  ROG VX Equity            Sell            -5000  175.51580
2012-12-07  ROG VX Equity             Buy             5000  184.90000
2012-12-11  ROG VX Equity            Sell            -3000  188.50000
2012-12-20  ROG VX Equity            Sell            -5000  185.80000

运用

transactions_ind.groupby(transactions_ind.index).sum()

删除"Ticker"和"Transaction"列,因为它们填充了非数字值.另外,当我总结"Number_of_units"列时,我很想知道如何处理"事务"列中的不同字符串.希望大熊猫有一个单行班车.谢谢你的帮助!

Answer 1

你可以用agg与first和sum:

df = df.groupby(df.index).agg({'Ticker': 'first',
                                'Transaction': 'first',
                                'Number_of_units':sum, 
                                'Price': 'first'})
#reorder columns
df = df[['Ticker','Transaction','Number_of_units','Price']]
print df
                   Ticker Transaction  Number_of_units     Price
Date                                                            
2012-10-11  ROG VX Equity         Buy            12000  182.0000
2012-10-16  ROG VX Equity        Sell            -5000  184.7000
2012-11-16  ROG VX Equity        Sell            -5000  175.5158
2012-12-07  ROG VX Equity         Buy             5000  184.9000
2012-12-11  ROG VX Equity        Sell            -3000  188.5000
2012-12-20  ROG VX Equity        Sell            -5000  185.8000