这本书是我自学Python的第一本书，里面的习题都在寒假已经完成，由于当时博客尚未搭建，故里面题目的答案并未发表。现在在开发项目博客没有新内容更新，因此这段实践会陆续上传原来的习题答案。每个题目均为自己设计的代码，优化与重构方面与标准答案可能有所不同。
参考教材：《Python编程从入门到实践》 【美】 Eric Matthes 著
Chapter9
9-1 餐馆：创建一个名为Restaurant的类，其方法__init__()设置两个属性：restaurant_name和cuisine_type。创建一个名为describe_restaurant()的方法和一个名为open_restaurant()的方法，其中前者打印前述两项信息，而后者打印一条消息，指出餐馆正在营业。
根据这个类创建一个名为restaurant的实例，分别打印其两个属性，再调用前述两个方法。
#!/usr/bin/env python
# -*- coding:utf-8 -*-
class Restaurant:
"""创建一个与餐馆有关的类"""
def __init__(self, restaurant_name, cuisine_type):
"""初始化属性restaurant和cuisine_type"""
self.restaurant_name = restaurant_name
self.cuisine_type = cuisine_type
def describe_restaurant(self):
"""有关餐馆的一些基础信息"""
print(" The restaurant name is {}.".format(self.restaurant_name))
print("The restaurant's cuisine type is {}.".format(self.cuisine_type))
def open_restaurant(self):
"""说明餐馆正在营业"""
print("{} is opening now.".format(self.restaurant_name))
restaurant = Restaurant("Yangxin", "Chinese")
restaurant.describe_restaurant()
restaurant.open_restaurant()9-2 用户：创根据你为完成练习9-1而编写的类创建三个实例，并对每个实例调用方法describe_restaurant()。
#!/usr/bin/env python
# -*- coding:utf-8 -*-
class Restaurant:
"""创建一个与餐馆有关的类"""
def __init__(self, restaurant_name, cuisine_type):
"""初始化属性restaurant和cuisine_type"""
self.restaurant_name = restaurant_name
self.cuisine_type = cuisine_type
def describe_restaurant(self):
"""有关餐馆的一些基础信息"""
print("\nThe restaurant name is {}.".format(self.restaurant_name))
print("The restaurant's cuisine type is {}.".format(self.cuisine_type))
def open_restaurant(self):
"""说明餐馆正在营业"""
print("{} is opening now.".format(self.restaurant_name))
restaurant_1 = Restaurant("Yangxin", "Chinese")
restaurant_1.describe_restaurant()
restaurant_1.open_restaurant()
restaurant_2 = Restaurant("King", "pizza")
restaurant_2.describe_restaurant()
restaurant_3 = Restaurant("Queen", "sandwich")
restaurant_3.describe_restaurant()9-3 用户：创建一个名为User的类，其中包含属性first_name和last_name，还有用户简介通常会存储的其他几个属性。在类User中定义一个名为describe_user()的方法，它打印用户信息摘要；再定义一个名为great_user()的方法，它向用户发出个性化的问候。
创建多个表示不同用户的实例，并对每个实例都调用上述两个方法。
#!/usr/bin/env python
# -*- coding:utf-8 -*-
class User:
"""创建一个与用户相关的类"""
def __init__(self, first_name, last_name, username, emile, location):
"""初始化各属性"""
self.first_name = first_name
self.last_name = last_name
self.username = username
self.emile = emile
self.location = location
def describe_user(self):
"""创建一个描述用户信息的函数"""
print("{} {}'s username is {},his(her) emile is {},his(her) location is {}."
.format(self.first_name.title(),
self.last_name.title(),
self.username,
self.emile,
self.location.title()))
def greet_user(self):
"""创建一个打招呼的函数"""
print("Hello,{} {},next to meet you.".format(self.first_name, self.last_name))
user = User("Chen", "Xili", "fire wolf", "1239968427@qq.com", "yangxin")
user.describe_user()
user.greet_user()9-4 就餐人数：在为完成练习9-1而编写的程序中，添加一个名为number_served的属性，并将其默认值设置为0。根据这个类创建一个名为restaurant的实例；打印有多少人在这家餐馆就餐过，然后修改这个值并再次打印它。
添加一个名为set_number_served()的方法，他让你能够设置就餐人数。调用这个方法并向它传递一个值，然后再次打印这个值。
添加一个名为increment_number_served()的方法，他让你能够将就餐人数递增。调用这个方法并向它传递一个这样的值：你认为这家店餐馆每天可能接待的就餐人数。
#!/usr/bin/env python
# -*- coding:utf-8 -*-
class Restaurant:
"""A class representing a restaurant."""
def __init__(self, name, cuisine_type):
"""Initialize the restaurant."""
self.name = name.title()
self.cuisine_type = cuisine_type
self.number_served = 0
def describe_restaurant(self):
"""Display a summary of the restaurant."""
msg = self.name + " serves wonderful " + self.cuisine_type + "."
print("\n" + msg)
def open_restaurant(self):
"""Display a message that the restaurant is open."""
msg = self.name + " is open. Come on in!"
print("\n" + msg)
def set_number_served(self, number_served):
"""Allow user to set the number of customers that have been served."""
self.number_served = number_served
def increment_number_served(self, additional_served):
"""Allow user to increment the number of customers served."""
self.number_served += additional_served
restaurant = Restaurant('the mean queen', 'pizza')
restaurant.describe_restaurant()
print("\nNumber served: " + str(restaurant.number_served))
restaurant.number_served = 430
print("Number served: " + str(restaurant.number_served))
restaurant.set_number_served(1257)
print("Number served: " + str(restaurant.number_served))
restaurant.increment_number_served(239)
print("Number served: " + str(restaurant.number_served))9-5 尝试登录次数：在为完成练习9-3而编写的User类中，添加一个名为login_attempt的属性。编写一个名为increment_login_attempts()的方法，它将属性login_attempts的值加1.再编写一个名为reset_login_attempts()的方法，它将属性login_attempts的值重置为0。
根据User类创建一个实例。再调用方法increment_login_attempts()多次。打印属性login_attempts的值，确认它被正确地递增；然后，调用方法reset_login_attempts()。并再次打印属性login_attempts的值，确认它被重置为0。
#!/usr/bin/env python
# -*- coding:utf-8 -*-
class User:
"""创建一个与用户相关的类"""
def __init__(self, first_name, last_name, username, emile, location):
"""初始化各属性"""
self.first_name = first_name
self.last_name = last_name
self.username = username
self.emile = emile
self.location = location
self.login_attempts = 0
def describe_user(self):
"""创建一个描述用户信息的函数"""
print("{} {}'s username is {},his(her) emile is {},his(her) location is {}."
.format(self.first_name.title(),
self.last_name.title(),
self.username,
self.emile,
self.location.title()))
def greet_user(self):
"""创建一个打招呼的函数"""
print("Hello,{} {},next to meet you.".format(self.first_name, self.last_name))
def increment_login_attempts(self):
"""添加一个名为login——attempts的属性"""
self.login_attempts += 1
def reset_login_attempts(self):
"""将其重置为0"""
self.login_attempts = 0
user = User('chen', "xili", 'fire_wolf', '1239968427@qq.com', 'yangxin')
user.describe_user()
user.greet_user()
# 打印调用多次后的值
user.increment_login_attempts()
user.increment_login_attempts()
user.increment_login_attempts()
print("Login attempt : {}".format(str(user.login_attempts)))
user.reset_login_attempts()
print("Login attempt : {}".format(str(user.login_attempts)))9-6 冰淇淋小店：冰淇淋小店是一种特殊的餐馆。编写一个名为IceCreamStand的类，让它继承你为练习9-1或练习9-4而编写的Restaurant类。这两个版本的Restaurant类都可以，挑选你更喜欢的那个即可。添加一个名为flavors的属性，用于存储一个由各种口味的冰淇淋组成的列表。编写一个显示这些冰淇淋的方法。创建一个IceCreamStand实例，并调用这个方法。
#!/usr/bin/env python
# -*- coding:utf-8 -*-
class Restaurant:
"""创建一个与餐馆有关的类"""
def __init__(self, restaurant_name, cuisine_type):
"""初始化属性restaurant和cuisine_type"""
self.restaurant_name = restaurant_name
self.cuisine_type = cuisine_type
def describe_restaurant(self):
"""有关餐馆的一些基础信息"""
print(" The restaurant name is {}.".format(self.restaurant_name))
print("The restaurant's cuisine type is {}.".format(self.cuisine_type))
def open_restaurant(self):
"""说明餐馆正在营业"""
print("{} is opening now.".format(self.restaurant_name))
class IceCreamStand(Restaurant):
"""冰淇淋小店的独特之处"""
def __init__(self, name, cuisine_type='ice_cream'):
"""初始化冰淇淋小店的属性"""
super().__init__(name, cuisine_type)
self.flavors = []
def show_flavors(self):
"""展示不同口味的冰淇淋"""
print("\nWe have the following flavors available:")
for flavor in self.flavors:
print("-" + flavor.title())
big_one = IceCreamStand('The Big One')
big_one.flavors = ['vanilla', 'chocolate', 'black cherry']
big_one.describe_restaurant()
big_one.show_flavors()9-7 管理员：管理员是一种特殊的用户。编写一个名为Admin的类，让它继承你为完成练习9-3或练习9-5而编写的User类。添加一个名为privileges的属性，用于存储一个由字符串（如”can add post”、”can delete post”、”can ban user”等）组成的列表。编写一个名为show_privileges()的方法，它显示管理员的权限。创建一个Admin实例，并调用这个方法。
#!/usr/bin/env python
# -*- coding:utf-8 -*-
class User:
"""创建一个与用户相关的类"""
def __init__(self, first_name, last_name, username, email, location):
"""初始化各属性"""
self.first_name = first_name
self.last_name = last_name
self.username = username
self.email = email
self.location = location
def describe_user(self):
"""创建一个描述用户信息的函数"""
print("{} {}'s username is {},his(her) emile is {},his(her) location is {}."
.format(self.first_name.title(),
self.last_name.title(),
self.username,
self.email,
self.location.title()))
def greet_user(self):
"""创建一个打招呼的函数"""
print("Hello,{} {},next to meet you.".format(self.first_name, self.last_name))
class Admin(User):
# 这个用户的独特之处
def __init__(self, first_name, last_name, username, email, location):
"""重新定义这个特殊的用户"""
super().__init__(first_name, last_name, username, email, location)
self.privileges = []
# 展示这个用户的特殊信息
def show_privileges(self):
print("\nPrivileges:")
for privilege in self.privileges:
print("-" + privilege)
user = Admin("Chen", "Xili", "fire wolf", "1239968427@qq.com", "yangxin")
user.describe_user()
user.privileges = ['can add post',
'can delete post',
'can ban user',
]
user.show_privileges()9-8 权限：编写一个名为Privileges的类，它只有一个属性——privileges，其中存储了练习9-7所说的字符串列表。将方法show_privileges()移到这个类中。在Admin类中，将一个Privileges实例用作其属性。创建一个Admin实例，并使用方法show_privileges()来显示其权限。
#!/usr/bin/env python
# -*- coding:utf-8 -*-
class User:
"""创建一个与用户相关的类"""
def __init__(self, first_name, last_name, username, email, location):
"""初始化各属性"""
self.first_name = first_name
self.last_name = last_name
self.username = username
self.email = email
self.location = location
def describe_user(self):
"""创建一个描述用户信息的函数"""
print("{} {}'s username is {},his(her) emile is {},his(her) location is {}."
.format(self.first_name.title(),
self.last_name.title(),
self.username,
self.email,
self.location.title()))
def greet_user(self):
"""创建一个打招呼的函数"""
print("Hello,{} {},next to meet you.".format(self.first_name, self.last_name))
class Admin(User):
# 这个用户的独特之处
def __init__(self, first_name, last_name, username, email, location):
"""重新定义这个特殊的用户"""
super().__init__(first_name, last_name, username, email, location)
self.privileges = Privileges()
class Privileges:
# 一个贮存管理员的类
def __init__(self, privileges=[]):
self.privileges = privileges
def show_privileges(self):
print("\nPrivileges:")
if self.privileges:
for privilege in self.privileges:
print("-" + privilege)
else:
print("- This user has no privileges.")
eric = Admin('eric', 'matthes', 'e_matthes', 'e_matthes@example.com', 'alaska')
eric.describe_user()
eric.privileges.show_privileges()
print("\nAdding privileges...")
eric_privileges = [
'can reset passwords',
'can moderate discussions',
'can suspend accounts',
]
eric.privileges.privileges = eric_privileges
eric.privileges.show_privileges()9-9 电瓶升级：在本节最后一个electric_car.py版本中，给Battery类添加一个名为upgrade_battery()的方法。这个方法检查电瓶容量，如果它不是85，就将它设置为85。创建一辆电瓶容量为默认值的电动汽车，调用方法get_range()，然后对电瓶进行升级，并再次调用get_range()。你会看到这辆汽车的续航里程增加了。
#!/usr/bin/env python
# -*- coding:utf-8 -*-
class Car():
"""A simple attempt to represent a car."""
def __init__(self, manufacturer, model, year):
"""Initialize attributes to describe a car."""
self.manufacturer = manufacturer
self.model = model
self.year = year
self.odometer_reading = 0
def get_descriptive_name(self):
"""Return a neatly formatted descriptive name."""
long_name = str(self.year) + ' ' + self.manufacturer + ' ' + self.model
return long_name.title()
def read_odometer(self):
"""Print a statement showing the car's mileage."""
print("This car has " + str(self.odometer_reading) + " miles on it.")
def update_odometer(self, mileage):
"""
Set the odometer reading to the given value.
Reject the change if it attempts to roll the odometer back.
"""
if mileage >= self.odometer_reading:
self.odometer_reading = mileage
else:
print("You can't roll back an odometer!")
def increment_odometer(self, miles):
"""Add the given amount to the odometer reading."""
self.odometer_reading += miles
class Battery():
"""A simple attempt to model a battery for an electric car."""
def __init__(self, battery_size=60):
"""Initialize the battery's attributes."""
self.battery_size = battery_size
def describe_battery(self):
"""Print a statement describing the battery size."""
print("This car has a " + str(self.battery_size) + "-kWh battery.")
def get_range(self):
"""Print a statement about the range this battery provides."""
if self.battery_size == 60:
range = 140
elif self.battery_size == 85:
range = 185
message = "This car can go approximately " + str(range)
message += " miles on a full charge."
print(message)
def upgrade_battery(self):
# 检查电瓶容量
if self.battery_size == 60:
self.battery_size = 85
print("Upgraded the battery to 85 kWh.")
else:
print("The battery is already upgraded.")
class ElectricCar(Car):
"""Models aspects of a car, specific to electric vehicles."""
def __init__(self, manufacturer, model, year):
"""
Initialize attributes of the parent class.
Then initialize attributes specific to an electric car.
"""
super().__init__(manufacturer, model, year)
self.battery = Battery()
print("Make an electric car, and check the battery:")
my_tesla = ElectricCar('tesla', 'model s', 2016)
my_tesla.battery.describe_battery()
print("\nUpgrade the battery, and check it again:")
my_tesla.battery.upgrade_battery()
my_tesla.battery.describe_battery()
print("\nTry upgrading the battery a second time.")
my_tesla.battery.upgrade_battery()
my_tesla.battery.describe_battery()9-10 导入Restaurant类：将最新的Restaurant类存储在一个模块中。在另一个文件中，导入Restaurant类，创建一个Restaurant实例，并调用Restaurant的一个方法，以确认import语句正确无误。
restaurant.py:
class Restaurant():
"""A class representing a restaurant."""
def __init__(self, name, cuisine_type):
"""Initialize the restaurant."""
self.name = name.title()
self.cuisine_type = cuisine_type
self.number_served = 0
def describe_restaurant(self):
"""Display a summary of the restaurant."""
msg = self.name + " serves wonderful " + self.cuisine_type + "."
print("\n" + msg)
def open_restaurant(self):
"""Display a message that the restaurant is open."""
msg = self.name + " is open. Come on in!"
print("\n" + msg)
def set_number_served(self, number_served):
"""Allow user to set the number of customers that have been served."""
self.number_served = number_served
def increment_number_served(self, additional_served):
"""Allow user to increment the number of customers served."""
self.number_served += additional_servedfrom restaurant import Restaurant
channel_club = Restaurant('the channel club', 'steak and seafood')
channel_club.describe_restaurant()
channel_club.open_restaurant()9-11 导入Admin类：以为完成练习9-8而做的工作为基础，将User、Privileges和Admin类存储在一个模块中，再创建一个文件，在其中创建一个Admin实例并对其调用方法show_privileges()，以确认一切都能正常地运行。
user.py:
#!/usr/bin/env python
# -*- coding:utf-8 -*-
class User():
"""Represent a simple user profile."""
def __init__(self, first_name, last_name, username, email, location):
"""Initialize the user."""
self.first_name = first_name.title()
self.last_name = last_name.title()
self.username = username
self.email = email
self.location = location.title()
self.login_attempts = 0
def describe_user(self):
"""Display a summary of the user's information."""
print("\n" + self.first_name + " " + self.last_name)
print(" Username: " + self.username)
print(" Email: " + self.email)
print(" Location: " + self.location)
def greet_user(self):
"""Display a personalized greeting to the user."""
print("\nWelcome back, " + self.username + "!")
def increment_login_attempts(self):
"""Increment the value of login_attempts."""
self.login_attempts += 1
def reset_login_attempts(self):
"""Reset login_attempts to 0."""
self.login_attempts = 0
class Admin(User):
"""A user with administrative privileges."""
def __init__(self, first_name, last_name, username, email, location):
"""Initialize the admin."""
super().__init__(first_name, last_name, username, email, location)
# Initialize an empty set of privileges.
self.privileges = Privileges([])
class Privileges():
"""Stores privileges associated with an Admin account."""
def __init__(self, privileges):
"""Initialize the privileges object."""
self.privilege = privileges
def show_privileges(self):
"""Display the privileges this administrator has."""
for privilege in self.privileges:
print("- " + privilege)from user import Admin
eric = Admin('eric', 'matthes', 'e_matthes', 'e_matthes@example.com', 'alaska')
eric.describe_user()
eric_privileges = [
'can reset passwords',
'can moderate discussions',
'can suspend accounts',
]
eric.privileges.privileges = eric_privileges
print("\nThe admin " + eric.username + " has these privileges: ")
eric.privileges.show_privileges()9-12 多个模块：将User类存储在一个模块中，并将Privileges和Admin类存储在另一个模块中。再创建一个文件，在其中创建一个Admin实例，并对其调用方法show_privileges()，以确认一切都依然能够正常地运行。
user.py:
#!/usr/bin/env python
# -*- coding:utf-8 -*-
class User():
"""Represent a simple user profile."""
def __init__(self, first_name, last_name, username, email, location):
"""Initialize the user."""
self.first_name = first_name.title()
self.last_name = last_name.title()
self.username = username
self.email = email
self.location = location.title()
self.login_attempts = 0
def describe_user(self):
"""Display a summary of the user's information."""
print("\n" + self.first_name + " " + self.last_name)
print(" Username: " + self.username)
print(" Email: " + self.email)
print(" Location: " + self.location)
def greet_user(self):
"""Display a personalized greeting to the user."""
print("\nWelcome back, " + self.username + "!")
def increment_login_attempts(self):
"""Increment the value of login_attempts."""
self.login_attempts += 1
def reset_login_attempts(self):
"""Reset login_attempts to 0."""
self.login_attempts = 0admin.py:
from user import User
class Admin(User):
"""A user with administrative privileges."""
def __init__(self, first_name, last_name, username, email, location):
"""Initialize the admin."""
super().__init__(first_name, last_name, username, email, location)
# Initialize an empty set of privileges.
self.privileges = Privileges([])
class Privileges():
"""Stores privileges associated with an Admin account."""
def __init__(self, privileges):
"""Initialize the privileges object."""
self.privilege = privileges
def show_privileges(self):
"""Display the privileges this administrator has."""
for privilege in self.privileges:
print("- " + privilege)from admin import Admin
eric = Admin('eric', 'matthes', 'e_matthes', 'e_matthes@example.com', 'alaska')
eric.describe_user()
eric_privileges = [
'can reset passwords',
'can moderate discussions',
'can suspend accounts',
]
eric.privileges.privileges = eric_privileges
print("\nThe admin " + eric.username + " has these privileges: ")
eric.privileges.show_privileges()9-13 使用OrderedDict：在练习6-4中，你使用了一个标准字典表示词汇表。请使用OrderdDict类来重写这个程序，并确认输出的顺序与你在字典中添加键-值对的顺序一致。
#!/usr/bin/env python
# -*- coding:utf-8 -*-
from collections import OrderedDict
words = OrderedDict()
words = {'for': '循环方式',
'print': '打印输出在屏幕显示',
'pop()': '从列表结尾中删除数据',
'sort': '按字母从小到大永久排序',
'del': '删除某个数据',
'set()': '找出列表中独一无二的元素',
'value()': '提取字典中包含的值',
'if': '假设语句',
'keys()': '只提取字典中包含的名称',
'append()': '添加数据',
}
for name, value in words.items():
print(name + ":" + value)9-14 骰子：模块random包含以各种方式生成随机数的函数，其中的randint()返回一个位于指定范围内的整数，例如，下面的代码返回一个1~6内的整数：
from random import randint
x = randint(1, 6)请创建一个Die类，它包含一个名为sides的属性，该属性的默认值为6。编写一个名为roll_die()的方法，它打印位于1和骰子面数之间的随机数。创建一个6面的骰子，再掷10次。
创建一个10面的骰子和一个20面的骰子，并将它们都掷10次。
#!/usr/bin/env python
# -*- coding:utf-8 -*-
from random import randint
class Die: # 创建一个Die类
def __init__(self, slide=6): # 初始化
self.slide = slide
def roll_die(self):
return randint(1, self.slide)
d6 = Die()
results = []
for roll_number in range(10):
result = d6.roll_die()
results.append(result)
print("\n10 rolls of a 6-sided die:")
print(results)
d10 = Die(10)
results = []
for roll_number in range(10):
result = d10.roll_die()
results.append(result)
print("\n10 rolls of a 10-slide die:")
print(results)
d20 = Die(20)
results = []
for roll_number in range(10):
result = d20.roll_die()
results.append(result)
print("\n10 rolls of a 20-slide die:")
print(results)
