参数'high'的类型不正确（预计numpy.ndarray，得到系列）

Question

我一直在尝试修复此代码以搜索解决方案（请参阅我的标题中的错误消息）。它似乎与df系列的索引有关。我看到我打印的日期，但无法解决它。我可以找到一种可行的方法来设置日期作为索引，在转换为np数组之前可能需要它吗？

            import datetime
            import talib
            import numpy as np
            import pandas as pd
            from numpy  import array
            from pandas_datareader import data, wb

            start_date = datetime.datetime(2010, 1, 1)
            end_date = datetime.datetime(2013, 1, 27)
            stocks = ['AAPL', 'SPY']

            df = data.DataReader(stocks, 'yahoo', start_date, end_date)

            high = pd.DataFrame(df.ix['High'])
            low = pd.DataFrame(df.ix['Low'])
            close = pd.DataFrame(df.ix['Close'])

            for stock in stocks:  
            slowk, slowd = talib.STOCH(high[stock],  
                                   low[stock],  
                                   close[stock],  
                                   fastk_period=5,  
                                   slowk_period=3,  
                                   slowk_matype=0,  
                                   slowd_period=3,  
                                   slowd_matype=0)


            slowk = slowk[-1]  
            slowd = slowd[-1]  
            STO = slowk - slowd  

            print('STO', STO)