Question

有人可以帮帮我吗？我正在

ValueError: The truth value of a Series is ambiguous. Use a.empty, a.bool(), a.item(), a.any() or a.all()

来自以下代码：

import pandas as pd

testdf = pd.read_csv('../../IBM.csv')

print testdf
print "------------"
testdf['NHigh'] = 0
print testdf

if testdf['Close'] > testdf['Open']:
    testdf['Nhigh'] = testdf['Close'] * testdf['High']

print "********"
print tested

我要做的是创建一个由两个值填充的新列现有列，但仅在条件为真时才显示。

形状是一个库存数据框，其中包含以下列 - Open, High, Low, Close等，我想根据之间的操作添加新列（NHigh）如果Close是＆gt;，请说High和Close该行的High。

谢谢，如果你能提供帮助......

Answer 1

我认为您可以使用loc和fillna：

print testdf
                       Open    High     Low   Close  Volume
Date_Time                                                  
1997-02-03 09:04:00  3046.0  3048.5  3046.0  3047.5     505
1997-02-03 09:27:00  3043.5  3043.5  3043.0  3043.0      56
1997-02-03 09:28:00  3043.0  3044.0  3043.0  3044.0      32
1997-02-03 09:29:00  3044.5  3044.5  3044.5  3044.5      63
1997-02-03 09:30:00  3045.0  3045.0  3045.0  3045.0      28
1997-02-03 09:31:00  3045.0  3045.5  3045.0  3045.5      75

print testdf['Close'] > testdf['Open']            
Date_Time
1997-02-03 09:04:00     True
1997-02-03 09:27:00    False
1997-02-03 09:28:00     True
1997-02-03 09:29:00    False
1997-02-03 09:30:00    False
1997-02-03 09:31:00     True
dtype: bool

testdf.loc[testdf['Close'] > testdf['Open'],'Nhigh'] = testdf['Close'] * testdf['High']
testdf['Nhigh'] = testdf['Nhigh'].fillna(0)
print testdf
                       Open    High     Low   Close  Volume       Nhigh
Date_Time                                                              
1997-02-03 09:04:00  3046.0  3048.5  3046.0  3047.5     505  9290303.75
1997-02-03 09:27:00  3043.5  3043.5  3043.0  3043.0      56        0.00
1997-02-03 09:28:00  3043.0  3044.0  3043.0  3044.0      32  9265936.00
1997-02-03 09:29:00  3044.5  3044.5  3044.5  3044.5      63        0.00
1997-02-03 09:30:00  3045.0  3045.0  3045.0  3045.0      28        0.00
1997-02-03 09:31:00  3045.0  3045.5  3045.0  3045.5      75  9275070.25

其他解决方案使用numpy.where：

testdf['Nhigh']=np.where(testdf['Close'] > testdf['Open'], testdf['Close']*testdf['High'], 0)
print testdf
                       Open    High     Low   Close  Volume       Nhigh
Date_Time                                                              
1997-02-03 09:04:00  3046.0  3048.5  3046.0  3047.5     505  9290303.75
1997-02-03 09:27:00  3043.5  3043.5  3043.0  3043.0      56        0.00
1997-02-03 09:28:00  3043.0  3044.0  3043.0  3044.0      32  9265936.00
1997-02-03 09:29:00  3044.5  3044.5  3044.5  3044.5      63        0.00
1997-02-03 09:30:00  3045.0  3045.0  3045.0  3045.0      28        0.00
1997-02-03 09:31:00  3045.0  3045.5  3045.0  3045.5      75  9275070.25

Python：如何使用现有列中的数据填充新的Pandas数据帧列

1 个答案: