Python 多条件数据帧的lambda和loc函数

发布于01月19日

我在我的python应用程序中遇到了这个问题.我需要在我的数据框中添加一个名为"ValueOverlap"的最新列(这个值是我自己编造的)，其中包含多个条件和计算结果.

Date	Open	High	Low	Close	PrevHigh	PrevLow	Direction	PrevDirection	ValueOverlap
31/12/1995	0,2879	0,3170	0,1429	0,1864	0,4475	0,2824	Bearish	Bearish	38
31/12/1996	0,1886	0,2640	0,1138	0,1172	0,3170	0,1429	Bearish	Bearish	13
31/12/1997	0,1217	0,3906	0,1205	0,3655	0,2640	0,1138	Bullish	Bearish	38
31/12/1998	0,3761	1,0536	0,2857	0,9180	0,3906	0,1205	Bullish	Bullish	47
31/12/1999	0,9364	1,3426	0,2433	0,2656	1,0536	0,2857	Bearish	Bullish	34
31/12/2000	0,2656	0,4843	0,2578	0,3911	1,3426	0,2433	Bullish	Bearish	47
31/12/2001	0,3938	0,4673	0,2386	0,2559	0,4843	0,2578	Bearish	Bullish	46
31/12/2002	0,2564	0,4466	0,2271	0,3816	0,4673	0,2386	Bullish	Bearish	32
31/12/2003	0,3848	1,2423	0,3782	1,1500	0,4466	0,2271	Bullish	Bullish	45
31/12/2004	1,1568	2,6950	1,1179	2,5675	1,2423	0,3782	Bullish	Bullish	37
31/12/2005	2,5850	3,3271	1,7914	3,0300	2,6950	1,1179	Bullish	Bullish	46
31/12/2006	3,0818	7,2486	2,9250	7,0743	3,3271	1,7914	Bullish	Bullish	32
31/12/2007	7,1168	7,1521	2,8264	3,0482	7,2486	2,9250	Bearish	Bullish	30
31/12/2008	3,0671	7,6411	2,7929	7,5261	7,1521	2,8264	Bullish	Bearish	36
31/12/2009	7,6225	11,6664	6,7946	11,5200	7,6411	2,7929	Bullish	Bullish	16
31/12/2010	11,6300	15,2393	11,0893	14,4643	11,6664	6,7946	Bullish	Bullish	30
31/12/2011	14,6214	25,1811	14,6071	19,0061	15,2393	11,0893	Bullish	Bullish	48
31/12/2012	19,7793	20,5407	13,7536	20,0364	25,1811	14,6071	Bullish	Bullish	48
31/12/2013	19,8457	29,9375	17,6268	27,5950	20,5407	13,7536	Bullish	Bullish	16
31/12/2014	27,8475	33,6350	23,0000	26,3150	29,9375	17,6268	Bearish	Bullish	28
31/12/2015	25,6525	29,6725	22,3675	28,9550	33,6350	23,0000	Bullish	Bearish	44
31/12/2016	28,9500	44,3000	28,6900	42,3075	29,6725	22,3675	Bullish	Bullish	20
31/12/2017	42,5400	58,3675	36,6475	39,4350	44,3000	28,6900	Bearish	Bullish	37
31/12/2018	38,7225	73,4925	35,5000	73,4125	58,3675	36,6475	Bullish	Bearish	47
31/12/2019	74,0600	138,7900	53,1525	132,6900	73,4925	35,5000	Bullish	Bullish	16
31/12/2020	133,5200	182,1300	116,2100	177,5700	138,7900	53,1525	Bullish	Bullish	16
31/12/2021	177,8300	182,9400	125,8700	129,9300	182,1300	116,2100	Bearish	Bullish	34
31/12/2022	130,2800	199,6200	124,1700	193,6000	182,9400	125,8700	Bullish	Bearish	21

我使用以下代码测试了df.loc函数:

df.loc[(df['PrevDirection'] == 'Bullish') & (df['Direction'] == 'Bullish'), 'Value_Overlap'] = min((df['PrevHigh'] - df['Low']) / (df['High'] - df['Low']) * 100, (df['PrevHigh'] - df['Low']) / (df['PrevHigh'] - df['PrevLow']) * 100)
df.loc[(df['PrevDirection'] == 'Bearish') & (df['Direction'] == 'Bearish'), 'Value_Overlap'] = min((df['High'] - df['PrevLow']) / (df['High'] - df['Low']) * 100, (df['High'] - df['PrevLow']) / (df['PrevHigh'] - df['PrevLow']) * 100)

并将lambda函数与下面的代码一起使用:

df['Value_Overlap'] = df.apply(lambda x: min((df['PrevHigh'] - df['Low']) / (df['High'] - df['Low']) * 100, (df['PrevHigh'] - df['Low']) / (df['PrevHigh'] - df['PrevLow']) * 100) if x['PrevDirection'] == 'Bullish' and x['Direction'] == 'Bullish' else min((df['High'] - df['PrevLow']) / (df['High'] - df['Low']) * 100, (df['High'] - df['PrevLow']) / (df['PrevHigh'] - df['PrevLow']) * 100) if x['PrevDirection'] == 'Bearish' and x['Direction'] == 'Bearish' else 0, axis=1)

在展位中的代码是相同的错误:"ValueError: The truth value of a Series is ambiguous. Use a.empty, a.bool(), a.item(), a.any() or a.all()."

有什么办法来解决这个问题吗？提前谢谢你了！

import numpy as np v1 = (df['PrevHigh'] - df['Low']) / (df['High'] - df['Low']) * 100 v2 = (df['PrevHigh'] - df['Low']) / (df['PrevHigh'] - df['PrevLow']) * 100 bullish = np.min([v1, v2], axis=0) v1 = (df['High'] - df['PrevLow']) / (df['High'] - df['Low']) * 100 v2 = (df['High'] - df['PrevLow']) / (df['PrevHigh'] - df['PrevLow']) * 100 bearish = np.min([v1, v2], axis=0) m = (df['PrevDirection'] == 'Bullish') & (df['Direction'] == 'Bullish') df.loc[m, 'Value_Overlap'] = bullish[m] m = (df['PrevDirection'] == 'Bearish') & (df['Direction'] == 'Bearish') df.loc[m, 'Value_Overlap'] = bearish[m]

>>> df.loc[:, 'Direction':] Direction PrevDirection ValueOverlap Value_Overlap 0 Bearish Bearish 38 -151.847365 1 Bearish Bearish 13 104.766187 2 Bullish Bearish 38 NaN 3 Bullish Bullish 47 13.660633 4 Bearish Bullish 34 NaN 5 Bullish Bearish 47 NaN 6 Bearish Bullish 46 NaN 7 Bullish Bearish 32 NaN 8 Bullish Bullish 45 7.915750 9 Bullish Bullish 37 -14.662895 10 Bullish Bullish 46 -99.101387 11 Bullish Bullish 32 43.625020 12 Bearish Bullish 30 NaN 13 Bullish Bearish 36 NaN 14 Bullish Bullish 16 17.375508 15 Bullish Bullish 30 11.845724 16 Bullish Bullish 48 5.978816 17 Bullish Bullish 48 108.071685 18 Bullish Bullish 16 23.669653 19 Bearish Bullish 28 NaN 20 Bullish Bearish 44 NaN 21 Bullish Bullish 20 -12112.778236 22 Bearish Bullish 37 NaN 23 Bullish Bearish 47 NaN 24 Bullish Bullish 16 -39.293262 25 Bullish Bullish 16 -0.436205 26 Bearish Bullish 34 NaN 27 Bullish Bearish 21 NaN

Python 多条件数据帧的lambda和loc函数

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