This project was created to help evaluate the cost of various mortgages. The mortgage classes in mortgage.py are from John Guttag's excellent book Introduction to Computation and Programing using Python. The avalance.py file contains a host of helper functions used to simulate and evaluate various mortgages based on the Mortgage objects in the mortgage.py file.

It should be noted that this simulation will potentially overpay a final payments. This overpayment can present some confusing end results (e.g. the total sum paid across multiple mortgages will be divisible by the budget amount).

The loans are all fairly generic, this can be used for mortgages, but also car payments, or student loans.

A simple simulation can be performed as follows:

budget = 1000
ex = Fixed(loan=110000.0, r=.0375, months=360)
while ex.loan_complete() == False:
    amt = budget - ex.payment
    ex.makePayment(amt)

A comparison of loans can be performed as follows:

loan1 = Fixed(loan=25000.0, r=0.03, months=60)
loan2 = Fixed(loan=2000.0, r=0.24, months=12)

loan_list = [loan1,loan2]
budget = 1000

# avalanche using select_loan_rate
ava = avalanche(loan_list_a,budget,select_loan_rate)
avalanche_summary(ava)
print('Total Payments\t\tInterest Paid')
print(totals(ava))

The avalanche function can take two methods for selecting which loan to pay-off, keeping in mind that the loan will be paid off in its entirety before the algorithm chooses another loan. Examples as follows:

select_loan_rate

ava = avalanche(loan_list_a,budget,select_loan_rate)
avalanche_summary(ava)

select_loan_pmt

int_pmt = avalanche(loan_list_b,budget,select_loan_pmt)
avalanche_summary(int_pmt)