amort.py

#!/usr/bin/env python3

import pandas as pd
import numpy as np
import matplotlib.pyplot as plt
import textwrap
from tabulate import tabulate

def amort(principal, rate, n):
    return principal * (rate * ((1 + rate) ** n)) / ((1 + rate) ** n - 1)


def compute_schedule(bal, pmt, rate):
    while bal > 0:
        new_bal = bal - (pmt - (bal * rate))
        period_interest = (bal * rate)
        period_principal = pmt - (bal * rate)
        if new_bal > 0:
            yield (new_bal, period_interest, period_principal)
        bal = new_bal


def amort_table(loan_amt, pmt, rate):
    df = pd.DataFrame(
        columns=['Amount', 'Interest', 'Principal', 'Balance'],
        index = np.arange(1, 361, 1)
    )
    for x, (b, i, p) in enumerate(compute_schedule(loan_amt, pmt, rate)):
        df.loc[x + 1] = pd.Series(
            {
                'Amount': round(pmt, 2),
                'Interest': round(i, 2),
                'Principal': round(p, 2),
                'Balance': round(b, 2)
            }
        )

    fig = plt.figure()
    ax = fig.add_subplot(111)
    ax.bar(np.arange(1, 361, 1), df.Principal, 1, label="Principal")
    ax.bar(np.arange(1, 361, 1), df.Interest, 1, bottom=df.Principal, label="Interest")
    ax2 = ax.twinx()
    ax2.plot(np.arange(1, 361, 1), df.Balance, color='red')
    ax.legend(loc='upper right')
    plt.show()

    # print(df.to_markdown())

def dollar_fmt(var):
    return f'${var:>12,.2f}'

def indent(txt, spaces=2):
    return "\n".join(" "*spaces + ln for ln in txt.splitlines())

class color:
   PURPLE = '\033[95m'
   CYAN = '\033[96m'
   DARKCYAN = '\033[36m'
   BLUE = '\033[94m'
   GREEN = '\033[92m'
   YELLOW = '\033[93m'
   RED = '\033[91m'
   BOLD = '\033[1m'
   UNDERLINE = '\033[4m'
   END = '\033[0m'

def main():
    required_fha = 331_760.00
    asking_price = 349_000.00
    closing_costs_percent = 0.015
    closing_costs = closing_costs_percent * asking_price
    purchase = asking_price + closing_costs
    pct_down = 0.05
    down_pmt = purchase * pct_down
    loan_amt = purchase - down_pmt
    annual_rate = 0.0375
    rate = annual_rate / 12
    n = 30 * 12
    if loan_amt - required_fha > 0:
        loan_fha_str = color.RED + f'${loan_amt - required_fha:>12,.2f}' + color.END
    else:
        loan_fha_str = color.GREEN + f'${loan_amt - required_fha:>12,.2f}' + color.END

    print('\n' + color.UNDERLINE + color.BLUE + color.BOLD + "Loan Terms:" + color.END)
    inputs_table = [
        ['Asking Price:', dollar_fmt(asking_price)],
        ['Closing Costs:', dollar_fmt(closing_costs), f'@ {closing_costs_percent*100:.2f}% asking price'],
        ['Purchase Price:', dollar_fmt(purchase)],
        ['Down Payment:', f'${down_pmt:>12,.2f}', f'@ {pct_down*100:.2f}% purchase price'],
        ['Loan Amount:', f'${loan_amt:>12,.2f}'],
        ['FHA Maximum:', f'${required_fha:>12,.2f}', 'low-cost region maximum'],
        ['Δ FHA/Loan:', f'{loan_fha_str}', 'constrained: Δ < 0'],
        ['Period Rate:', f'{rate*100:.2f}%', f'@ {annual_rate*100:.2f}% fixed annual'],
        ['Periods:', n]
    ]
    for row in inputs_table:
        row[0] = color.BOLD + row[0] + color.END
    print(indent(tabulate(inputs_table, colalign=('left', 'right', 'right'), tablefmt='plain')))

    print('\n' + color.UNDERLINE + color.BLUE + color.BOLD + "Monthly Summary:" + color.END)
    annual_pmi = loan_amt * 0.0082
    monthly_pmi = annual_pmi / 12
    annual_taxes = 1700.00
    monthly_taxes = 1700.00 / 12
    annual_insurance = 727.32
    monthly_insurance = annual_insurance / 12
    monthly_pmt = amort(loan_amt, rate, n)
    monthly_total = monthly_pmt + monthly_taxes + monthly_pmi + monthly_insurance
    pmt_table = [
        ['Monthly Payment:', f'${monthly_pmt:>10,.2f}'],
        ['Property Taxes:', f'${monthly_taxes:>10,.2f}', f'@ ${annual_taxes:>9,.2f} Annual'],
        ['Mortgage Insurance:', f'${monthly_pmi:>10,.2f}', f'@ ${annual_pmi:>9,.2f} Annual'],
        ['Home Insurance:', f'${monthly_insurance:>10,.2f}', f'@ ${annual_insurance*12:>9,.2f} Annual'],
        ['Total Monthly Payment:', f'${monthly_total:>10,.2f}']
    ]
    for row in pmt_table:
        row[0] = color.BOLD + row[0] + color.END
    print(indent(tabulate(pmt_table, colalign=('left', 'right', 'right'), tablefmt='plain')))

    gs_savings = 15_500
    ally_savings = 1_200
    car_money = 1_300
    total_savings = gs_savings + ally_savings + car_money
    inspections = 800
    break_lease = 1_200
    moving = 500
    total_expenses = down_pmt + inspections + break_lease + moving
    remaining_reserves = total_savings - total_expenses
    if remaining_reserves < 0:
        remaining_reserves_str = color.RED + f'${remaining_reserves:>12,.2f}' + color.END
    else:
        remaining_reserves_str = color.GREEN + f'${remaining_reserves:>12,.2f}' + color.END

    print('\n' + color.UNDERLINE + color.BLUE + color.BOLD + "Expenses Summary:" + color.END)
    upfront = [
        ['Total Savings:', f'${total_savings:>12,.2f}'],
        ['Total Expenses:', f'${(total_expenses)*-1:>12,.2f}'],
        ['   - Down Payment', f'${down_pmt*-1:>12,.2f}'],
        ['   - Inspections & Appraisal', f'${inspections*-1:>12,.2f}'],
        ['   - Break Lease', f'${break_lease*-1:>12,.2f}'],
        ['   - Moving', f'${moving*-1:>12,.2f}'],

        ['Remaining:', remaining_reserves_str]
    ]
    for row in upfront:
        row[0] = color.BOLD + row[0] + color.END
    print(indent(tabulate(upfront, colalign=('left', 'right'), tablefmt='plain')))

    print('\n' + color.UNDERLINE + color.BLUE + color.BOLD + "Financial Summary:" + color.END)
    savings = [
        ['Goldman Sachs', f'$ {gs_savings:,.2f}'],
        ['Ally', f'$ {ally_savings:,.2f}'],
        ['Car Money', f'$ {car_money:,.2f}'],
        ['Total Saved', f'${gs_savings + ally_savings + car_money:,.2f}']
    ]

    pay_rate = 6_228
    annual_salary = pay_rate * 12
    debt_ratio = (monthly_total / pay_rate) * 100
    pay_rates = [
        ['Pay Rate:', f'${pay_rate:>10,.2f}'],
        ['Annual Salary:', f'${annual_salary:>10,.2f}'],
        ['Mortgage-Income Ratio:', f'{debt_ratio:,.2f}%']
    ]
    for row in pay_rates:
        row[0] = color.BOLD + row[0] + color.END
    print(indent(tabulate(pay_rates, colalign=('left', 'right'), tablefmt='plain')))
    # print(tabulate(savings, colalign=('left', 'right')))


if __name__ == '__main__':
    main()