如何在pandas python中传递函数(外部编写)并分配给列？

Question

def calc1(tentative_valuations, previous_buying_price):
  return tentative_valuations - previous_buying_price

#mortgage calculator
def calc2(loanper, previous_buying_price):
  return loanper * previous_buying_price



#indicative paid interest to date **REQUIRES ACCESSOR** ###################
calc3 = int(lookups((ym_between(b, a)[0]), (ym_between(b, a)[1]), 'Cum Interest Paid'))


# #net indicative capital gain today #######################################
calc4 = calc1(tentative_valuations, previous_buying_price) - calc3
#print(calc4)


# #to calculate psf before
def calc5(previous_buying_price, area):
  return previous_buying_price/area

# #to calculate psf after
def calc6(tentative_valuations, area):
  return tentative_valuations/area


#print(calc5(previous_buying_price,area))
#print(calc6(tentative_valuations, area))

# #annualised ##########################################
def calc7():
  return round((((calc6(tentative_valuations, area)/calc5(previous_buying_price, area))**(1/(ym_between(b,a)[0]+ ym_between(b,a)[1]/12))) - 1)*100,2)
#no problem
#print(calc7())

#indicative paid principal to date
calc8 = int(lookups((ym_between(b, a)[0]), (ym_between(b, a)[1]), 'Cumulative Paid Principal'))

#indicative balance 
calc9 = (loanper * previous_buying_price) - calc8

  #create the dataframe.
    df2 = pd.DataFrame(columns=['Gross Indicative Capital Gain Today', 'Net Indicative Capital Gain Today','Indicative Average Gross Annual Capital Gain', 'Indicative Paid Principal to Date ', 'Indicative Paid Interest to Date',
                        'Indicative Balance'])
    df2['Gross Indicative Capital Gain Today'] = calc1(tentative_valuations, previous_buying_price)
    df2['Net Indicative Capital Gain Today'] = calc3
    df2['Indicative Average Gross Annual Capital Gain'] = calc7()
    df2['Indicative Paid Principal to Date'] = calc8
    df2['Indicative Paid Interest to Date'] = calc3
    df2['Indicative Balance'] = calc9
    df2.head()

当我调用df2时，似乎只出现了标题？所有的计算要么是变量，要么是有输出的函数。刚接触熊猫(我的第二天学习)，非常感谢你们的帮助，谢谢你们:)

Answer 1

您不能将诸如int、bool之类的类型分配给数据框中的特定列，就像您在数组中将其包围在如下数组中一样：

df2['Indicative Paid Principal to Date'] = [calc8]

如果要向新行添加值，可以执行以下操作

new_values = [calc1(tentative_valuations, previous_buying_price), calc3, calc7, calc8, calc3, calc9]
df2.loc[0] = new_values

Answer 2

直接调用df2不会做任何事情。

将最后一行更改为：

print(df2)