def __init__(self, main=None):
if not main:
raise ValueError("No value provided for main")
self.main = main
self.canvas = tk.Canvas(
self.main.root,
background='#FFFFFF',
**constants.canvas_dimensions)
self.axes = Axes(
canvas=self.canvas,
**constants.axes_display,
**constants.axes_scale)
self.canvas.grid()
for p in constants.monthly_payment_range():
a = constants.initial_balance['default']
i = constants.interest_rate['default']
payoff_months = payments_to_payoff(a, i / 12, p)
if payoff_months is None or payoff_months / 12 > constants.axes_scale['y_max']:
point = self.axes.add_point(p, 0)
self.axes.hide_point(point)
else:
self.axes.add_point(p, payoff_months / 12)
def calculate_payoff_times(self):
"""Calculates payoff time data and stores the results in the database"""
with self.database.transaction():
current_id = 0
for Bo in constants.initial_balance_range():
for r in constants.interest_rate_range():
for p in constants.monthly_payment_range():
print("Calculating for initial balance {0}, rate {1}, monthly payment {2}".format(Bo, r, p))
t = time_until_zero_balance(r, Bo, p)
if t is not None:
database.create_point(current_id, Bo, r, p, t)
current_id += 1
def update_axes(self, a, i):
"""Updates the points on the axes to reflect the new values of a and i.
Args:
a (numeric): The initial balance of the loan
i (numeric): The interest rate per payment period (NOT per year) in decimal form
"""
for p in constants.monthly_payment_range():
try:
payoff_months = payments_to_payoff(a, i / 12, p)
except AssertionError:
# payments_to_payoff failed preconditions
continue
point = self.axes.get_point_by_x(p)
if payoff_months is None or payoff_months / 12 > constants.axes_scale['y_max']:
self.axes.hide_point(point)
else:
self.axes.show_point(point)
self.axes.move_point(point, p, payoff_months / 12)
