PyQt5 rapid development and actual combat 10.2 compound interest calculation && 10.3 refresh blog clicks

PyQt5快速开发与实战

10. 第10章 PyQt5 实战一：Classic program development

10.2 复利计算 && 10.3 Refresh blog hits

10.2.1 Compound interest calculation business

复利计算,It means after each interest accrual period,The interest accrued in the current period must be added to the principal,以计算下期的利息.这样,in each interest period,The interest of the previous period will become the interest-earning principal,即以利生利,也就是俗称的“利滚利”.This involves the present value of compound interest、Compound interest future value and compound interest calculation formula.

复利现值,It means in the case of calculating compound interest,To reach a certain amount of money in the future,The principal that must be invested now.所谓复利,Also known as lee-on-galley,It refers to the return of a deposit or investment,A way to make a new round of investment with capital and profit.

复利终值,It refers to the interest earned on the principal within the agreed period,Add the interest to the principal and then calculate the interest,The sum of the principal that is rolled over to the end of the agreed period.

复利计算公式：

其中P为本金,i为利率,nfor the holding period.

举例：

例如:某人用20000RMB yuan to invest in a project,annual rate of return5%,So what is the interest income after two years?
Calculated according to the compound interest formula,The interest income earned is:
20000X(1+5%)^2-2000×(1+5%)×(1+5%)
= 2000 ×1.05 ×1.05= 22050 （元)

10.2.2 Interface and logic implementation

# -*- coding: utf-8 -*-

''' 【简介】 银行复利计算 '''
from __future__ import division

import sys
from PyQt5.QtWidgets import (QApplication, QComboBox, QDialog,
        QDoubleSpinBox, QGridLayout, QLabel)

class Form(QDialog):

   def __init__(self, parent=None):
      super(Form, self).__init__(parent)

      principalLabel = QLabel("Principal:")
      self.principalSpinBox = QDoubleSpinBox()
      self.principalSpinBox.setRange(1, 1000000000)
      self.principalSpinBox.setValue(1000)
      self.principalSpinBox.setPrefix("RMB ")
      rateLabel = QLabel("Rate:")
      self.rateSpinBox = QDoubleSpinBox()
      self.rateSpinBox.setRange(1, 100)
      self.rateSpinBox.setValue(5)
      self.rateSpinBox.setSuffix(" %")
      yearsLabel = QLabel("Years:")
      self.yearsComboBox = QComboBox()
      self.yearsComboBox.addItem("1 year")
      self.yearsComboBox.addItems(["{0} years".format(x)
                            for x in range(2, 31)])
      amountLabel = QLabel("Amount")
      self.amountLabel = QLabel()

      grid = QGridLayout()
      grid.addWidget(principalLabel, 0, 0)
      grid.addWidget(self.principalSpinBox, 0, 1)
      grid.addWidget(rateLabel, 1, 0)
      grid.addWidget(self.rateSpinBox, 1, 1)
      grid.addWidget(yearsLabel, 2, 0)
      grid.addWidget(self.yearsComboBox, 2, 1)
      grid.addWidget(amountLabel, 3, 0)
      grid.addWidget(self.amountLabel, 3, 1)
      self.setLayout(grid)

      self.principalSpinBox.valueChanged.connect(self.updateUi)
      self.rateSpinBox.valueChanged.connect(self.updateUi)
      self.yearsComboBox.currentIndexChanged.connect(self.updateUi)
      
      self.setWindowTitle("Interest")
      self.updateUi()

   def updateUi(self):
      principal = self.principalSpinBox.value()
      rate = self.rateSpinBox.value()
      years = self.yearsComboBox.currentIndex() + 1
      amount = principal * ((1 + (rate / 100.0)) ** years)
      self.amountLabel.setText("RMB {0:.2f}".format(amount))

if __name__=="__main__":
   from pyqt5_plugins.examples.exampleqmlitem import QtCore
   QtCore.QCoreApplication.setAttribute(QtCore.Qt.AA_EnableHighDpiScaling)
   app = QApplication(sys.argv)
   form = Form()
   form.show()
   sys.exit(app.exec_()) 

10.3 Refresh blog hits

import sys
import time

from PyQt5.QtWebEngineWidgets import QWebEngineView
from PyQt5.QtCore import *
from PyQt5.QtWidgets import  *

class WebView(QWebEngineView):
     def __init__(self ):
        super(WebView, self).__init__()
        url = 'https://blog.csdn.net/weixin_44226181?type=blog'
        self.load( QUrl( url ) )             
        self.show()
        QTimer.singleShot(1000*3 , self.close)  
      

if __name__ == '__main__':   
   app = QApplication(sys.argv)
   web = WebView()  
   print('### exec succeed !')
   sys.exit(app.exec_())      

call the main window

if __name__ == '__main__' :   
   for i in range(5): 
       os.system("python openweb.py")
       print("Refreshing page. 次数 =>" ,  i)
       time.sleep(5)