1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
|
import argparse
import math
import sys
from tabulate import tabulate, SEPARATING_LINE
def calc_payments(principal, annual_interest, installments):
p = principal
i = annual_interest / 100 / 12 # Monthly equivalent.
n = installments
def fmt(x):
return f"{math.ceil(x*100)/100:.2f}"
table = [["Time", "Outstanding Debt", "Monthly Installment", "Interest Paid", "Amount Amortised"]]
monthly_installment = p * (i * (1 + i)**n) / ((1 + i)**n - 1)
debt = principal
total_interest = 0
total_amortised = 0
for k in range(n):
interest = i * debt
amortised = monthly_installment - interest
table.append([k] + [fmt(x) for x in [debt, monthly_installment, interest, amortised]])
total_interest += interest
total_amortised += amortised
debt -= amortised
total_interest_pct = total_interest / principal * 100
table.append(SEPARATING_LINE)
table.append(["Total", "", "Amount Paid", "Interest Paid", "Amount Amortised"])
table.append(["", ""] + [
fmt(monthly_installment * n),
fmt(total_interest) + f" ({fmt(total_interest_pct)}%)",
fmt(total_amortised)])
return table
def main():
parser = argparse.ArgumentParser()
parser.add_argument("-p", "--principal", type=float, default=100000, help="Principal")
parser.add_argument("-i", "--interest", type=float, default=5, help="Annual interest %")
parser.add_argument("-n", "--installments", type=int, default=300, help="Number of installments")
args = parser.parse_args()
table = calc_payments(args.principal, args.interest, args.installments)
print(tabulate(table))
return 0
if __name__ == "__main__":
sys.exit(main())
|
