请问这个错误是什么原因造成的？

Question

import numpy as np
import pandas as pd
import matplotlib.pyplot as plt
import datetime

pf_value=pd.read_excel(r'C:\Users\Kaixin Feng\Downloads\rawdata.xlsx')
pf_value = pf_value.astype(float)
market = pd.read_excel(r'C:\Users\Kaixin Feng\Downloads\market.xlsx')
market = market.astype(float)
data = [pf_value,market]

for i in range(len(data)):
data[i].set_index(['date'],inplace=True)
data[i].iloc[:,0]=data[i].iloc[:,0].astype(float)

print(data[0])
结果出现：
File "C:\Users\Kaixin Feng\anaconda3\lib\site-packages\pandas\core\arrays\datetimelike.py", line 424, in astype
raise TypeError(msg)

TypeError: Cannot cast DatetimeArray to dtype float64

源数据：
market.xlsx:

rawdata.xlsx:

Answer 1

是因为pf_value = pf_value.astype(float)和market = market.astype(float)这两句代码，会对读取的数据框整体进行类型转换，而date列是DatetimeArray类型，不能转换为浮点数。解决办法是取出数值列转换即可，上述两句分别改成如下就可以了：

pf_value.iloc[:,1:] = pf_value.iloc[:,1:].astype(float)
market.iloc[:,1:]= market.iloc[:,1:].astype(float)

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