Pandas和Scipy TypeError:“NoneType”和“float”的实例之间不支持“<”

Question

import numpy as np 
import pandas as pd 
import math
from scipy import stats

hqm_columns = [
    'Ticker',
    'Price',
    'Number of Shares to Buy',
    'One-Year Price Return',
    'One-Year Return Percentile',
    'Six-Month Price Return',
    'Six-Month Return Percentile',
    'Three-Month Price Return',
    'Three-Month Return Percentile',
    'One-Month Price Return',
    'One-Month Return Percentile',
    'HQM Score'
]

#create the data frame using pandas
hqm_dataframe = pd.DataFrame(columns = hqm_columns)
#data created using iex cloud API

#calculate the percentile scores
time_periods = [
                'One-Year',
                'Six-Month',
                'Three-Month',
                'One-Month'
                ]
for row in hqm_dataframe.index:
    for time_period in time_periods:
        change_col = f'{time_period} Price Return'
        percentile_col = f'{time_period} Return Percentile'
        hqm_dataframe.loc[row, percentile_col] = stats.percentileofscore(hqm_dataframe[change_col], hqm_dataframe.loc[row, change_col])/100

根据最后一行代码，我得到以下错误：

Traceback (most recent call last):
  File "C:\Users\Areet\Documents\cs\python\algoTrading\quantMomentum2.py", line 77, in <module>
    hqm_dataframe.loc[row, percentile_col] = stats.percentileofscore(hqm_dataframe[change_col], hqm_dataframe.loc[row, change_col])/100
  File "C:\Users\Areet\AppData\Roaming\Python\Python39\site-packages\scipy\stats\stats.py", line 2017, in percentileofscore
    left = np.count_nonzero(a < score)
TypeError: '<' not supported between instances of 'NoneType' and 'float'

前面的代码行实例化并声明错误行中使用的变量。在阅读了scipy模块中的“percentileofscore”之后，我知道参数是一个数组和一个浮点。我不确定它为什么不将数据帧列识别为数组

Answer 1

hqm_dataframe=hqm_dataframe.expert_objects（）

上面的代码行将包含浮点值的列的数据类型设置为数据类型“float64”，而不是数据类型“object”。转换后，可以使用stats.percentileofscore函数比较列中的值