Calculate loan

loan.py

def loan2(R, M=[55000], L=8500000, F=3000000, P=12, verbose=0):
    # R is a list of rate of each year
    # M is a list of month pay-back of each year
    # P is period per year
    R = [1.0 * r for r in R]
    M = [1.0 * m for m in M]
    L = L * 1.0
    F = F * 1.0
    P = P * 1.0
    principal = L-F
    interest = 0.0
    paid = 0.0
    t = 0
    if verbose > 0:
        print('    period      remain      paid    principal    interest')
    while principal > 1e-5:
        if int(t/P) < len(R):
            r = R[int(t/P)]/P
        else:
            r = R[-1]/P
        if int(t/P) < len(M):
            m = M[int(t/P)]
        else:
            m = M[-1]
        if t > 1e5:
            raise ValueError('Over maximum iterations')
        interest = principal * r
        if principal - m + interest < 0:
            m = principal + interest
        if verbose > 0:
            print('%2d-%02d(%03d)  %10.2f  %8.2f  %11.2f  %10.2f' % (int(t/P), int(t)%int(P), int(t), principal-m+interest, m, m-interest, interest))
        principal = principal - m + interest
        paid += m
        t += 1
    principal = F

    tf = t
    while principal > 1e-5:
        r = 0.0
        if int(tf/P) < len(M):
            m = M[int(tf/P)]
        else:
            m = M[-1]
        if tf > 1e5:
            raise ValueError('Over maximum iterations')
        interest = principal * r
        if principal - m + interest < 0:
            m = principal + interest
        if verbose > 0:
            print('%2d-%02d(%03d)  %10.2f  %8.2f  %11.2f  %10.2f' % (int(tf/P), int(tf)%int(P), int(tf), principal-m+interest, m, m-interest, interest))
        principal = principal - m + interest
        paid += m
        tf += 1
    return t, t/P, tf/P, paid