更新DataFrame值

Question

这个DataFrame名为data ...

                    winner
 runner_name                         
 Steve                   0
 Joe                     0
 Marsha                  1
 Kent                    0

如果我创建一个占位符为0 ...

的新列

 data['weighted'] = 0

当我传递十进制值以在循环中更新它（经过一系列长时间的计算和其他事情之后）......

 data.ix[runner_name]['weighted'] = 45.88

...它会自动舍入数字。因此，框架变得......

                    winner  weighted
 runner_name                         
 Steve                   0        46
 Joe                     0        80
 Marsha                  1       100
 Kent                    0        80

如何防止它四舍五入？

Answer 1

分配一个浮动将导致Pandas为列提供float dtype：

data['weighted'] = 0.0

---

import pandas as pd
data = pd.DataFrame({'winner':[0,0,1,0]}, index=pd.Series(['Steve', 'Joe', 'Marsha', 'Kent'], name='runner_name'), )
data['weighted'] = 0.0
data.ix['Steve', 'weighted'] = 45.88
print(data)

产量

             winner  weighted
runner_name                  
Steve             0     45.88
Joe               0      0.00
Marsha            1      0.00
Kent              0      0.00

---

>>> print(data.dtypes)
winner        int64
weighted    float64
dtype: object