Calculate Floating Rate Amortization Table with optional Balloon Payment

amortization_dataframe.py

import pandas as pd
import numpy as np


def amort_table(principal, rate, annual_periods, term, future_value):
    rate /= 100
    per = np.arange(annual_periods * term) + 1
    ipmt = np.ipmt(rate=rate/12, per=per, nper=annual_periods * term, pv=principal, fv=-future_value)
    ppmt = np.ppmt(rate=rate/12, per=per, nper=annual_periods * term, pv=principal, fv=-future_value)
    # pmt = np.pmt(rate / 12, num_period * term, principal, fv=-future_value)
    pv_list = []
    for payment in per:
        index = payment - 1
        principal = principal + ppmt[index]
        pv_list.append(principal)
    return pd.DataFrame({'ppmt': ppmt, 'ipmt': ipmt, 'principal': pv_list})

if __name__ == "__main__":
    o_principal = 350000
    o_rate = 5
    o_rate_increase = 0.25
    o_term = 5
    o_period = 1
    o_num_period = 12
    o_future_value = 150000

    final_amort_table = None

    for period in np.arange(0, o_term + 1):

        if period == 0:
            temp_amort_table = amort_table(
                principal=o_principal,
                rate=o_rate,
                term=o_term,
                annual_periods=o_period * o_num_period,
                future_value=o_future_value
            )
            final_amort_table = temp_amort_table.ix[0:11]
        else:
            o_rate += o_rate_increase
            temp_amort_table = amort_table(
                principal=final_amort_table.tail(1)['principal'].values[0],
                rate=o_rate,
                term=o_term-period,
                annual_periods=o_period * o_num_period,
                future_value=o_future_value
            )
            final_amort_table = final_amort_table.append(temp_amort_table.ix[0:11], ignore_index=True)

    print(final_amort_table)