视频总结：
视频范围：week1
The recipe for deducing square root cannot be made into a real computer program because computers cannot guess a starting value for y.
answer : True
计算机不能根据经验猜初始值
程序计数器A program counter：
指向程序将执行的下一条命令points the computer to the next instruction to execute in the program.
Determines whether a string is legal：Syntax
Determines whether a string has meaning：Static semantics
Assigns a meaning to a legal sentence：Semantics
十一章总结
解决python3.x版本报错:No module named 'pylab'
conda install numpy
conda install scipy
conda install matplotlib
完整代码：
import pylab
def findPayment(loan, r, m):
"""
假设loan和r是浮点数， m是整数
返回一个总额为loan，月利率为r，期限为m个月的抵押贷款的每月还款额
"""
return loan*((r*(1+r)**m)/((1+r)**m - 1))
class Mortgage(object):
"""建立不同种类抵押贷款的抽象类"""
def __init__(self, loan, annRate, months):
self.loan = loan
self.rate = annRate/12.0
self.months = months
self.paid = [0.0]
self.outstanding = [loan]
self.payment = findPayment(loan, self.rate, months)
self.legend = None #description of mortgage
def makePayment(self):
self.paid.append(self.payment)
reduction = self.payment - self.outstanding[-1]*self.rate
self.outstanding.append(self.outstanding[-1] - reduction)
def getTotalPaid(self):
return sum(self.paid)
def __str__(self):
return self.legend
def plotPayments(self, style):
pylab.plot(self.paid[1:], style, label = self.legend)
def plotBalance(self, style):
pylab.plot(self.outstanding, style, label = self.legend)
def plotTotPd(self, style):
totPd = [self.paid[0]]
for i in range(1, len(self.paid)):
totPd.append(totPd[-1] + self.paid[i])
pylab.plot(totPd, style, label = self.legend)
def plotNet(self, style):
totPd = [self.paid[0]]
for i in range(1, len(self.paid)):
totPd.append(totPd[-1] + self.paid[i])
equityAcquired = pylab.array([self.loan] * len(self.outstanding))
equityAcquired = equityAcquired - pylab.array(self.outstanding)
net = pylab.array(totPd) - equityAcquired
pylab.plot(net, style, label = self.legend)
class Fixed(Mortgage):
def __init__(self, loan, r, months):
Mortgage.__init__(self, loan, r, months)
self.legend = 'Fixed, ' + str(r*100) + '%'
class FixedWithPts(Mortgage):
def __init__(self, loan, r, months, pts):
Mortgage.__init__(self, loan, r, months)
self.pts = pts
self.paid = [loan*(pts/100.0)]
self.legend = 'Fixed, ' + str(r*100) + '%, '\
+ str(pts) + ' points'
class TwoRate(Mortgage):
def __init__(self, loan, r, months, teaserRate, teaserMonths):
Mortgage.__init__(self, loan, teaserRate, months)
self.teaserMonths = teaserMonths
self.teaserRate = teaserRate
self.nextRate = r/12.0
self.legend = str(teaserRate*100)\
+ '% for ' + str(self.teaserMonths)\
+ ' months, then ' + str(r*100) + '%'
def makePayment(self):
if len(self.paid) == self.teaserMonths + 1:
self.rate = self.nextRate
self.payment = findPayment(self.outstanding[-1],self.rate,self.months - self.teaserMonths)
Mortgage.makePayment(self)
def compareMortgages(amt, years, fixedRate, pts, ptsRate,
varRate1, varRate2, varMonths):
totMonths = years*12
fixed1 = Fixed(amt, fixedRate, totMonths)
fixed2 = FixedWithPts(amt, ptsRate, totMonths, pts)
twoRate = TwoRate(amt, varRate2, totMonths, varRate1, varMonths)
morts = [fixed1, fixed2, twoRate]
for m in range(totMonths):
for mort in morts:
mort.makePayment()
plotMortgages(morts, amt)
def plotMortgages(morts, amt):
def labelPlot(figure, title, xLabel, yLabel):
pylab.figure(figure)
pylab.title(title)
pylab.xlabel(xLabel)
pylab.ylabel(yLabel)
pylab.legend(loc = 'best')
styles = ['k-', 'k-.', 'k:']
#给图编号赋名
payments, cost, balance, netCost = 0, 1, 2, 3
for i in range(len(morts)):
pylab.figure(payments)
morts[i].plotPayments(styles[i])
pylab.figure(cost)
morts[i].plotTotPd(styles[i])
pylab.figure(balance)
morts[i].plotBalance(styles[i])
pylab.figure(netCost)
morts[i].plotNet(styles[i])
labelPlot(payments, 'Monthly Payments of $' + str(amt) +
' Mortgages', 'Months', 'Monthly Payments')
labelPlot(cost, 'Cash Outlay of $' + str(amt) +
'Mortgages', 'Months', 'Total Payments')
labelPlot(balance, 'Balance Remaining of $' + str(amt) +
'Mortgages', 'Months', 'Remaining Loan Balance of $')
labelPlot(netCost, 'Net Cost of $' + str(amt) + ' Mortgages',
'Months', 'Payments - Equity $')
compareMortgages(amt=200000, years=30, fixedRate=0.07,pts = 3.25, ptsRate=0.05,varRate1=0.045, varRate2=0.095, varMonths=48)