Total Interest over Life of Loan

import pandas as pd
import numpy as np
import numpy_financial as npf

annual_interest_rate = 0.03
monthly_interest_rate = annual_interest_rate / 12
n_periods = 60
periods = np.arange(n_periods) + 1
loan_amount = 10000.

monthly_payment = (npf.pmt(monthly_interest_rate,
                           n_periods,
                           loan_amount)
                   .round(2) * -1 )

interest_per_month = (npf.ipmt(monthly_interest_rate,
                               periods,
                               n_periods,
                               loan_amount)
                      .round(2) * -1 )
total_interest = interest_per_month.sum()

loan_amount, annual_interest_rate, n_periods, total_interest, monthly_payment

loans = []

annual_interest_rate = 0.03
monthly_interest_rate = annual_interest_rate / 12
n_periods = 60
periods = np.arange(n_periods) + 1

for loan_amount in np.arange(10000, 46000, 1000):
    monthly_payment = (npf.pmt(monthly_interest_rate,
                               n_periods,
                               loan_amount)
                       .round(2) * -1 )

    interest_per_month = (npf.ipmt(monthly_interest_rate,
                                   periods,
                                   n_periods,
                                   loan_amount)
                          .round(2) * -1 )
    total_interest = interest_per_month.sum()
    
    loans.append((loan_amount, total_interest, monthly_payment, annual_interest_rate, n_periods))
    
loans = (pd.DataFrame(loans,
                      columns=['loan_amount', 'total_interest', 'monthly_payment', 
                               'annual_interest_rate', 'n_periods'])
         .set_index('loan_amount'))
loans