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| 1 | +#!/usr/bin/python3 |
| 2 | + |
| 3 | +import sys |
| 4 | +import getopt |
| 5 | + |
| 6 | + |
| 7 | + |
| 8 | +# Source resources: |
| 9 | +# https://www.statology.org/compound-interest-in-python/ |
| 10 | +# https://www.enki.com/post/how-to-calculate-compound-interest-in-python |
| 11 | +def calculate_compound_interest(principal: float, interest_rate: float, times_compounded: int, years_duration: int) -> float: |
| 12 | + """ |
| 13 | + INPUTS: |
| 14 | + principal = the initial deposit or loan amount |
| 15 | + interest_rate = annual interest rate in decimal form |
| 16 | + times_compounded = number of compounding periods per year |
| 17 | + years_duration = number of years the money is invested or borrowed |
| 18 | + CALCULATION: |
| 19 | + A = principal(1 + interest_rate/times_compounded)^times_compounded*years_duration |
| 20 | + RETURNS: |
| 21 | + amount = future value of the investment or loan, including interest |
| 22 | + """ |
| 23 | + amount = principal * (1 + interest_rate/times_compounded)**(times_compounded*years_duration) |
| 24 | + # or use python's pow() function: |
| 25 | + # amount = principal*(pow((1+interest_rate/times_compounded), times_compounded*years_duration)) |
| 26 | + return amount |
| 27 | + |
| 28 | + |
| 29 | +def main(argv): |
| 30 | + # From: https://github.com/mccright/PythonStuff/blob/main/githubfilestree.py |
| 31 | + if sys.version_info < (3, 10): |
| 32 | + raise Exception("Use only with Python 3.10 or higher") |
| 33 | + |
| 34 | + principal: float = '' |
| 35 | + interest_rate: float = '' |
| 36 | + times_compounded: int = '' |
| 37 | + years_duration: int = '' |
| 38 | + |
| 39 | + |
| 40 | + if not (sys.argv[1:]): |
| 41 | + print('Calculate future value of an investment or loan, including interest.') |
| 42 | + print('Inputs required: -p <principal> -r <interest_rate> -t <times_compounded> -y <years_duration>') |
| 43 | + """ |
| 44 | + principal = the initial deposit or loan amount |
| 45 | + interest_rate = annual interest rate in decimal form |
| 46 | + times_compounded = number of compounding periods per year |
| 47 | + years_duration = number of years the money is invested or borrowed') |
| 48 | + """ |
| 49 | + sys.exit(2) |
| 50 | + |
| 51 | + try: |
| 52 | + opts, args = getopt.getopt(argv, 'hp:r:t:y:', ['principal=','rate=','times=','years=']) |
| 53 | + except getopt.GetoptError as err: |
| 54 | + print(err) |
| 55 | + print('\nCalculate future value of an investment or loan, including interest.') |
| 56 | + print(f'{sys.argv[0] } -p <principal> -r <interest_rate> -t <times_compounded> -y <years_duration>') |
| 57 | + sys.exit(2) |
| 58 | + |
| 59 | + try: |
| 60 | + for opt, arg in opts: |
| 61 | + if opt == '-h': |
| 62 | + print('\nCalculate future value of an investment or loan, including interest.') |
| 63 | + print(f'{sys.argv[0] } -p <principal> -r <interest_rate> -t <times_compounded_per_year> -y <years_duration>\n') |
| 64 | + sys.exit() |
| 65 | + elif opt in ("-p", "--principal"): |
| 66 | + principal = float(arg) |
| 67 | + elif opt in ("-r", "--rate"): |
| 68 | + interest_rate = float(arg) |
| 69 | + elif opt in ("-t", "--times"): |
| 70 | + times_compounded = int(arg) |
| 71 | + elif opt in ("-y", "--years"): |
| 72 | + years_duration = int(arg) |
| 73 | + except Exception as err: |
| 74 | + print(err) |
| 75 | + print('\nCalculate future value of an investment or loan, including interest.') |
| 76 | + print(f'{sys.argv[0] } -p <principal> -r <interest_rate> -t <times_compounded> -y <years_duration>\n') |
| 77 | + sys.exit(2) |
| 78 | + |
| 79 | + |
| 80 | + """ |
| 81 | + principal: float = '' |
| 82 | + interest_rate: float = '' |
| 83 | + times_compounded: int = '' |
| 84 | + years_duration: int = '' |
| 85 | + """ |
| 86 | + |
| 87 | + total_amount = calculate_compound_interest(principal, interest_rate, times_compounded, years_duration) |
| 88 | + print(f"${principal:,.2f} at an interest rate of {interest_rate} compounded {times_compounded} times per year for {years_duration} years = ${total_amount:,.2f}") |
| 89 | + interest_earned = total_amount - principal |
| 90 | + print(f"${total_amount:,.2f} - ${principal:,.2f} = ${interest_earned:,.2f} interest.\n") |
| 91 | + |
| 92 | +if __name__ == '__main__': |
| 93 | + main(sys.argv[1:]) |
| 94 | + |
| 95 | + |
| 96 | + """ |
| 97 | + Think about using argparse instead of getopts: |
| 98 | + For example: |
| 99 | + https://github.com/mccright/PythonStuff/blob/main/lottery_numbers/PowerBall-MegaMillions.py |
| 100 | + |
| 101 | + python get user input from command line |
| 102 | + https://duckduckgo.com/?ia=web&origin=funnel_home_website&t=h_&q=python+get+user+input+from+command+line&chip-select=search |
| 103 | +
|
| 104 | + """ |
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