# amort

Generates an amortization schedule based on the principal, interest rate, term, and any additional payments towards principal.

## requirements

Only imports `argparse` and `json` for the main block of the script.

* saves results to a file `schedule.csv`
* does not access the web or internet

## usage

Invoke `make test` to generate a schedule based on loan of 100,000 over a 3 year term given an interest rate of 5.0% with a one-time payment towards principal of 5000 at the 13th month.

### extra payments

For extra payments towards principal, invoking the script will look like:

    python src/amort.py -p {principal} -i {interest rate} -t {years} --extra-payments extra_payments.json

A valid json file contains a list named `extra-payments`. Each element is an object with the attributes `payment-number` and `amount`.

    {
        "extra-payments" : [
            {
                "payment-number": 1,
                "amount": 500
            }, {
                "payment-number": 2,
                "amount": 500
            }, {
                "payment-number": 3,
                "amount": 500
            }
        ]
    }

* `payment-number` is the month when the payment has been made.
* `amount` is self-explanatory

## misc

This originated from me playing with ChatGPT. I asked it a question and it blurted out a semi-functional script as an answer. Then I made this repo to track the errors I fixed.