True/False

1. False
2. True
3. False
4. True
5. False
6. False
7. True
8. True
9. False
10. True

Multiple Choice

1. a
2. c
3. d
4. c
5. c
6. c
7. d
8. b
9. c
10. a

Discussion

1. While loop fragments: 

   1. sum = 0
      i = 1
      while i <= n:
          sum = sum + i
          i = i + 1

   2. sum = 0
      i = 1
      while i < 2*n:
          sum = sum + i
          i = i + 2

   3. sum = 0
      x = input("Enter a number: ")
      while x != 999:
          sum = sum + x
          x = input("Enter a number: ")

   4. count = 0
      while n > 1:
          n = n / 2
          count = count + 1

Programming Exercises

1.

解法一

def main():
    a = 0
    b = 1
    c = 1
    n = int(input("Enter n: "))
    # for i in range(n-1):
    i = 0
    while i < n - 1:
        i = i + 1
        c = a + b
        a = b
        b = c
    print("The figure is {0}.".format(c))
main()

解法二

# c08ex01.py
#    Nth fibonacci number

def main():
    print("This program calculates the nth Fibonacci value.\n")

    n = int(input("Enter the value of n: "))
    curr, prev = 1, 1
    for i in range(n-2):
        curr, prev = curr+prev, curr

    print("The nth Fibonacci number is", curr)

if __name__ == '__main__':
    main()

2.

解法一（没有用好函数和列表，缺乏简洁性）

def drawStruct():
    print('\n|----------------+',end = '')
    for i in range(8):
        print('-'*8+'+',end = '')
    print('--------|')

def drawLine():
    print("|{0:^16}|".format(' '),end = '')
    for i in range(9):
        print("{0:^8}|".format(' '),end = '')
    print()
    
def main():
    print('WCI'.center(100))
    print('-'*99)
    print("|{0:^15}|".format('V/ML/h \ T/℃'),end = '')
    for T in range(-20,61,10):
        print("{0:^8}|".format(T),end = '')
    drawStruct()
    for V in range(0,55,5):
        drawLine()
        print("|{0:^16}|".format(V),end = '')
        for T in range(-20,61,10):
            if V <= 3:
                WCI = '/'
                print("{0:^8}|".format(WCI),end = '')
            else:
                WCI = 35.74 + 0.6215 * T + (0.4275 * T - 35.75) * (V ** 0.16)
                print("{0:^8.2f}|".format(WCI),end = '')
        print()
    print('-'*99)  
if __name__ =="__main__" :
    main()

解法二（最佳解法，值得学习）

# c08ex02.py
#   Windchill Table

def windChill(t, v):
    if v > 3:
        chill = 35.74 + 0.6215*t - 35.75*(v**0.16) + 0.4275*t*(v**0.16)
    else:
        chill = t
    return chill

def main():

    # Print table headings
    print("Wind Chill Table\n\n")
    print("Temperature".center(70))
    print("MPH|", end=' ')
    temps = list(range(-20,61,10))
    for t in temps:
        print("{0:5}".format(t), end=' ')
    print("\n---+" + 55 * '-')

    # Print lines in table
    for vel in range(0,51,5):
        print("{0:3}|".format(vel), end=' ')
        for temp in temps:
            print("{0:5.0f}".format(windChill(temp, vel)), end=' ')
        print()
    print()

main()

3.

def main():
    apr = float(input("Enter the interest: "))
    n = 0
    while (1+apr)**n < 2:
        n = n + 1
    print('Principal will double after {0} years.'.format(n))

if __name__ == "__main__":
    main()

4

def main():
    n = int(input('Enter n: '))
    print('Syracuse:',n,end = ' ')
    while n != 1:
        
        n = syr(n)
        print(int(n),end = ' ')

def syr(x):
    if x % 2==0:s = x/2
    else:s = 3 * x + 1
    return s
if __name__ =='__main__':
    main()
    

5

解法一（更简洁易懂）

def main():
    n = int(input('Enter n(n>2): '))
    s = 0
    for i in range(2,n):
        if n % i == 0:
            print(i,end = ' ')
            s = s + 1
    if s == 0:
        print(n,'is prime.')
if __name__ == "__main__":
    main()
        
    

解法二（算法结构更老道）

# c08ex05.py
#   Primality tester

import math

def isPrime(n):
    if n % 2 == 0:
        return False
    factor = 3
    while factor <= math.sqrt(n):
        if n % factor == 0:
            return False
        factor = factor + 2
    return True

def main():
    print("Prime number tester\n")
    n = int(input("Enter a value to test: "))
    if isPrime(n):
        print(n, "is prime.")
    else:
        print(n, "is not prime.")

if __name__ == '__main__':
    main()

6

解法一

def main():
    n = int(input('Enter n(n>2): '))
    for j in range(2,n + 1):
        isPrime(j)

def isPrime(n):
    s = 0
    for i in range(2,n):
        if n % i == 0:
            s = s + 1
    if s == 0:
        print(n,end = ' ')

if __name__ == "__main__":
    main()
        
    

解法二

# c08ex06.py
#    primes to n

from c08ex05 import isPrime

def main():
    print("This program finds all prime numbers up to N\n")
    n = int(input("Enter the upper limit, n: "))
    print("primes: ", end=' ')
    for i in range(2,n+1):
        if isPrime(i):
            print(i, end=' ')
    print("Done")

if __name__ == '__main__':
    main()

7

解法一

def main():
    try:
        n = int(input('Enter n: '))
        t = 0
        if n % 2 == 0:
            m = n // 2
            for i in range(2,m):
                if isPrime(i) + isPrime(n - i) == 2:
                    t = t + 1
                    print('({0}) {1} {2}'.format(t,i,n-i))
                    
        else:   print('The number is not an even number!')
    except:
        print('Check the figure you input!')


def isPrime(n):
    s = 0
    for i in range(2,n):
        if n % i == 0:
            s = s + 1
    if s == 0:  return 1
    else:   return 0

if __name__ == '__main__':
    main()

解法二

# c08ex07.py
#    Goldbach tester

from c08ex05 import isPrime

def goldbach(x):
    cand = 3
    while cand < x/2:
        other = x - cand
        if isPrime(cand) and isPrime(other):
            return cand
        cand = cand + 2

def main():
    print("Goldbach checker\n")
    
    n = int(input("Enter an even natural number: "))
    if n % 2 != 0:
        print(n, "is not even!")
    else:
        prime1 = goldbach(n)
        prime2 = n - prime1
        print("{0} + {1} = {2}".format(prime1, prime2, n))

if __name__ == '__main__':
    main()

8.

def main():
    m = int(input('Enter m: '))
    n = int(input('Enter n: '))
    
    while m !=0:
        n , m = m , n % m
    print('GCD:',n)

if __name__ == '__main__':
    main()

9

解法一

def main():
    startRoute = float(input('Enter the route at first: '))
    totalRoute = 0
    totalGas = 0
    i = 0
    while True:
        rg = input('Enter the route and gas seperated by " ":').split()
        if rg == []:
            break
        i = i + 1
        route,gas = float(rg[0]),float(rg[1])
        MPG = (route - startRoute) / gas
        totalRoute =  totalRoute + route - startRoute
        startRoute = route
        totalGas = totalGas + gas
        print('Route{0} MPG: {1:.2f}.'.format(i,MPG))
    totalMPG = totalRoute / totalGas
    print('Total MPG: {0:.2f}'.format(totalMPG))

if __name__ == '__main__':
    main()

解法二

# c08ex09.py
#   Program to figure out gas mileage overa multiple-leg journey.

def main():
    print("This program calculates fuel efficiency over a multi-leg journey.")
    print("You should enter the gallons of gas consumed and miles traveled")
    print("for each leg. Just hit <Enter> to signal the end of the trip.")
    print()
    

    distance, fuel = 0.0, 0.0
    inStr = input("Enter gallons and miles (with a comma between): ")
    while inStr != "":
        inputs = inStr.split(",")
        gallons, miles = int(inputs[0]), int(inputs[1])
        print("MPG for this leg: {0:0.1f}".format(miles/gallons))
        distance = distance + miles
        fuel = fuel + gallons
        inStr = input("Enter gallons and miles (with a comma between): ")

    print()
    print("You traveled a total of {0:0.1f} miles on {1:0.1f} gallons."
          .format(distance, fuel))
    print("The fuel efficiency was {0:0.1f} miles per gallon."
          .format(distance/fuel))

if __name__ == '__main__':
    main()

10

解法一

def main():
    fname = input('Enter the name of the file: ')
    infile = open(fname,'r',encoding = 'utf-8')
    startRoute = float(infile.readline())
    totalRoute = 0
    totalGas = 0
    i = 0
    for line in infile.readlines():
        rg = line.split()
        if rg == []:
            break
        i = i + 1
        route,gas = float(rg[0]),float(rg[1])
        MPG = (route - startRoute) / gas
        totalRoute =  totalRoute + route - startRoute
        startRoute = route
        totalGas = totalGas + gas
        print('Route{0} MPG: {1:.2f}.'.format(i,MPG))
    totalMPG = totalRoute / totalGas
    print('Total MPG: {0:.2f}'.format(totalMPG))
infile.close()

if __name__ == '__main__':
    main()

解法二

# c08ex10.py
#     Batch fuel efficiency

def main():
    print("This program calculates fuel efficiency over a multi-leg journey.")
    print("It gets trip information from a file. Each line of the file should")
    print("have the gallons used and miles traveled (separated by a comma) for")
    print("one leg of the journey.\n")

    fname = input("What file contains the data? ")
    infile = open(fname,'r')

    distance, fuel = 0.0, 0.0
    for line in infile:
        inputs = line.split(",")
        gallons, miles = int(inputs[0]), int(inputs[1])

        print("Gallons: {0:0.1f}, Miles: {1:0.1f}, MPG: {2:0.1f}"
              .format(gallons, miles, miles/gallons))
        distance = distance + miles
        fuel = fuel + gallons
    infile.close()
    
    print("\nYou traveled a total of {0:0.1f} miles on {1:0.1f} gallons."
          .format(distance, fuel))
    print("The fuel efficiency was {0:0.1f} miles per gallon."
          .format(distance/fuel))

if __name__ == '__main__':
    main()

11

解法一

def main():
    i,hot,cold  = 1,0,0
    while True:
        temperature = input('Enter the average temperature of day{0}: '.format(i))
        if temperature == '':break
        t = float(temperature)
        if t < 60:hot = hot + 60 - t
        if t > 80:cold = cold + t - 80
        i = i + 1
    print('Cooling degree-days：{0}    Heating degree-days：{1}'.format(cold,hot))    

if __name__ == '__main__':
    main()

解法二（使用max语句替代if语句，更简洁，经验值得积累）

# c08ex11.py
#    heating/colling degree-days


def main():
    print("Heating and Cooling degree-day calculation.\n")

    heating = 0.0
    cooling = 0.0
    tempStr = input("Enter an average daily temperature: ")
    while tempStr != "":
        temp = float(tempStr)
        heating = heating + max(0, 60-temp)
        cooling = cooling + max(0, temp-80)
        tempStr = input("Enter an average daily temperature: ")

    print("\nTotal heating degree-days", heating)
    print("Total cooling degree-days", cooling)

if __name__ == '__main__':
    main()

    
    

12

def main():
    print("Heating and Cooling degree-day calculation.")
    fname = input("Enter name of file with average temperature data: ")
    infile = open(fname, 'r')

    heating = 0.0
    cooling = 0.0
    for line in infile:
        temp = float(line)
        heating = heating + max(0, 60-temp)
        cooling = cooling + max(0, temp-80)
    infile.close()

    print("\nTotal heating degree-days", heating)
    print("Total cooling degree-days", cooling)

if __name__ == '__main__':
    main()

13

解法一

from graphics import *
def main():
    win = GraphWin('线性回归方程演示',700,700)
    win.setBackground('white')
    win.setCoords(0,0,50,50)
    frame = Rectangle(Point(0,0),Point(4,2))
    frame.setFill(color_rgb(0,255,144))
    frame.draw(win)
    Text(Point(2,1),'Done').draw(win)
    sxy,sx,sy,sx2,sy2,n = 0,0,0,0,0,0
    while True:
        p = win.getMouse()
        px,py = p.getX(),p.getY()
        if px <= 4 and py <= 2:
            break
        p.draw(win)
        sxy = sxy + px * py
        sx2 = sx2 + px**2
        sy2 = sy2 + py**2
        sx = sx + px
        sy = sy + py
        n = n + 1
    a = Circle(Point(sx/n,sy/n),.30)
    a.setFill('red')
    a.setOutline('red')
    a.setWidth(2)
    a.draw(win)
    m = (sxy - sx*sy/n)/(sx2 - sx*sx/n)
    n = (sy - sx*m)/n
    l = Line(Point(0,n),Point(50,m*50 + n))
    l.setWidth(2)
    l.draw(win)
    
    win.getMouse()
    win.close()

if __name__ =='__main__':
    main()

解法二

from graphics import *

# These two "constants" are defined here so they can be used in multiple
#    functions to draw the done button and check to see if it is clicked in.

DoneX = 1.0   # x coordinate of done button upper right
DoneY = 0.75  # y coordinate of done button upper right

def createWindow():
    # Creates a 500x500 window titled "Linear Regression" and draws
    #    a "Done Button" in the lower left corner. The window coords
    #    run from 0,0 to 10,10, and the upper right corner of the button
    #    is located at (DoneX, DoneY).
    # Returns the window.
    win = GraphWin("Linear Regression", 500, 500)
    win.setCoords(0,0,10,10)
    doneButton = Rectangle(Point(.05,0), Point(DoneX, DoneY))
    doneButton.draw(win)
    Text(doneButton.getCenter(), "Done").draw(win)
    return win

def getPoint(w):
    # w is a GraphWin
    # Pauses for user to click in w. If user clicks somewhere other than
    #    the Done button, the point is drawn in w.
    # Returns the point clicked, or None if user clicked the Done button
    p = w.getMouse()
    if p.getX() > DoneX or p.getY() > DoneY:
        p.draw(w)
        return p
    else:
        return None

def slope(xb, yb, xx, xy, n):
    # Returns the slope of the line of best fit, m
    return (xy - n * xb * yb) / (xx - n*xb*xb)

def predict(x, xb, yb, m):
    # Returns a predicated value for y.
    return yb + m*(x-xb)

def getPoints(w):
    # Allows the user to make a series of mouse clicks in w until
    #    the user clicks in the Done button.
    # Returns: average of x values
    #          average of y values
    #          sum of the squares of the x values
    #          sum of the xy products
    #          the number of points clicked before Done
    sumX = 0.0
    sumY = 0.0
    sumXsq = 0.0
    sumXY = 0.0
    n = 0
    p = getPoint(w)
    while p != None:
        x,y = p.getX(), p.getY()
        sumX = sumX + x
        sumY = sumY + y
        sumXY = sumXY + x * y
        sumXsq = sumXsq + x * x
        n = n + 1
        p = getPoint(w)
    return sumX/n, sumY/n, sumXsq, sumXY, n

def main():
    # Draws a window, gets mouse clicks and then draws line of best
    #   fit through the points that were clicked.
    win = createWindow()
    xbar, ybar, sumXsq, sumXY, n = getPoints(win)
    m = slope(xbar, ybar, sumXsq, sumXY, n)
    y1 = predict(0, xbar, ybar, m)
    y2 = predict(10, xbar, ybar, m)
    regLine = Line(Point(0,y1), Point(10,y2))
    regLine.setWidth(2)
    regLine.draw(win)
    win.getMouse()
    win.close()

if __name__ == '__main__':
    main()

14 这是一道很好的题，Image对象很少练习。这道题可做典型。

from graphics import *

def openImage(picFile):
    
    img = Image(Point(0,0),picFile)
    width = img.getWidth()
    height = img.getHeight()
    win = GraphWin('',width,height)
    img.move(width//2,height//2)
    img.draw(win)
    return img

def convertToGray(img):
    for row in range(img.getWidth()):
        for col in range(img.getHeight()):
            r,g,b = img.getPixel(row,col)
            i = round(0.299*r + 0.587*g + 0.114*b)
            img.setPixel(row,col,color_rgb(i,i,i))
        update()

def main():
    print("This program converts an image to grayscale.")

    inFile = input("Enter the name of the gif file to convert: ")
    image = openImage(inFile)

    print('Convertin...',end = '')
    convertToGray(image)
    print('Done.')

    outFile = input('Enter filename for the converted image: ')
    image.save(outFile)


if __name__ =='__main__':
    main()

15

from graphics import *
def openFile(picFile):
    img = Image(Point(0,0),picFile)
    width,height = img.getWidth(),img.getHeight()
    win = GraphWin('',width,height)
    img.move(width//2,height//2)
    img.draw(win)
    return img

def convertColor(img):
    for row in range(img.getWidth()):
        for col in range(img.getHeight()):
            r,g,b = img.getPixel(row,col)
            img.setPixel(row,col,color_rgb(255-r,255-g,255-b))
        update()

def main():
    picFile = input("Enter the name of file to be converted: ")
    img = openFile(picFile)
    convertColor(img)
    outFile = input("Enter the name of the converted file: ")
    img.save(outFile)

if __name__ == '__main__':
    main()

16 有一个疑问，已经放在注释里了。日后精通python了，要解决！

from graphics import *
def handleKey(k,win):
    if k == 'p':
        win.setBackground('pink')
    elif k == 'w':
        win.setBackground('white')
    elif k == 'g':
        win.setBackground('lightgray')
    elif k == 'b':
        win.setBackground('lightblue')
    elif k == 'y':
        win.setBackground('yellow')
    elif k == 'r':
        win.setBackground('red')

        
def handleClick(pt,win):
    entry = Entry(pt,10)
    entry.draw(win)
    while True:
        key = win.getKey()
        if key in ['Return','Escape']:break
        #   We cannot use "if key is == 'Return' or 'Escape'"
        #   to replace" if key in ['Return','Escape']",but why?
    
    entry.undraw()
    typed = entry.getText()
    if key == 'Return':
        Text(pt,typed).draw(win)
    win.checkMouse()

def main():
    win = GraphWin('Click and Type',500,500)
    while True:
        key = win.checkKey()
        if key == 'q':
            break
        if  key:
            handleKey(key,win)
        pt = win.checkMouse()
        if pt:
            handleClick(pt,win)
    win.close()

main()