Calculadora do Pagamento Mensal de Empréstimo usando tkinter

from tkinter import * # Import tkinter
import math

class LoanCalculator:
    def __init__(self):
        window = Tk() # Create a window
        window.title("Loan Calculator")
        Label(window, text = "Annual Interest Rate").grid(row = 1,
            column = 1, sticky = W)
        Label(window, text = "Number of Years").grid(row = 2,
            column = 1, sticky = W)
        Label(window, text = "Loan Amount").grid(row = 3,
            column = 1, sticky = W)
        Label(window, text = "Monthly Payment").grid(row = 4,
            column = 1, sticky = W)
        Label(window, text = "Total Payment").grid(row = 5,
            column = 1, sticky = W)

        self.annualInterestRateVar = StringVar()
        Entry(window, textvariable = self.annualInterestRateVar,
            justify = RIGHT).grid(row = 1, column = 2)
        self.numberOfYearsVar = StringVar()
        Entry(window, textvariable = self.numberOfYearsVar,
            justify = RIGHT).grid(row = 2, column = 2)
        self.loanAmountVar = StringVar()
        Entry(window, textvariable = self.loanAmountVar,
            justify = RIGHT).grid(row = 3, column = 2)

        self.monthlyPaymentVar = StringVar()
        lblMonthlyPayment = Label(window, textvariable =
            self.monthlyPaymentVar).grid(row = 4, column = 2,
                sticky = E)
        self.totalPaymentVar = StringVar()
        lblTotalPayment = Label(window, textvariable =
            self.totalPaymentVar).grid(row = 5,
                column = 2, sticky = E)
        btComputePayment = Button(window, text = "Compute Payment"
            ,command = self.computePayment).grid(
                row = 6, column = 2, sticky = E)

        window.mainloop() # Create an event loop

    def computePayment(self):
        monthlyPayment = self.getMonthlyPayment(
            float(self.loanAmountVar.get()),
            float(self.annualInterestRateVar.get()) / 1200,
            int(self.numberOfYearsVar.get()))
        self.monthlyPaymentVar.set(format(monthlyPayment, '10.2f'))
        totalPayment = float(self.monthlyPaymentVar.get()) * 12 \
            * int(self.numberOfYearsVar.get())
        self.totalPaymentVar.set(format(totalPayment,'10.2f'))

    def getMonthlyPayment(self,
            loanAmount, monthlyInterestRate, numberOfYears):
        rate1=pow(1+monthlyInterestRate,numberOfYears*12)
        monthlyPayment = loanAmount * monthlyInterestRate*
                         rate1/(rate1-1)
        return monthlyPayment;

LoanCalculator()

Creador:Ethon Seaver (código aberto)