python基础（八）

'''
类
基于类创建对象时，每个对象都自动具备这种通用行为，然后可根据需要赋予每个对象独特的个性。
根据类来创建对象被称为实例化。

'''

#根据dog类创建的每个实例都将存储名字和年龄，赋予每条小狗蹲下和打滚的能力 sit() roll_over()
class Dog():
    
    def __init__(self, name, age):
        self.name = name
        self.age = age
        
    def sit(self):
        print(self.name.title() + " is now sitting.")
        
    def roll_over(self):
        print(self.name.title() + " rolled over!")

'''
实参self，python调用_init_方法来创建实例时，将自动传入实参self。

每个与类相关联的方法调用都自动传递实参self，它是指向实例本身的引用，让实例能够访问类中的属性和方法。

每当我们根据Dog类创建实例时，都只需给最后两个形参提供值。
self.name = name获取存储在形参name中的值，并将其存储到变量name中，然后该变量被关联到当前创建的实例。

这样可以通过实例访问的变量称为属性。
'''

#根据类创建实例
class Dog():
    
    
    def __init__(self, name, age):
        self.name = name
        self.age = age
        
    def sit(self):
        print(self.name.title() + " is now sitting.")
        
    def roll_over(self):
        print(self.name.title() + " rolled over!")

my_dog = Dog('peter', 10)
print("My dog's name is " + my_dog.name.title() + ".")
print("My dog is " + str(my_dog.age) + " years old.")

My dog's name is Peter.
My dog is 10 years old.

'''
1.访问属性
2.调用方法
3.创建多个实例
'''

my_dog.name

'peter'

my_dog.age

10

class Dog():
    
    
    def __init__(self, name, age):
        self.name = name
        self.age = age
        
    def sit(self):
        print(self.name.title() + " is now sitting.")
        
    def roll_over(self):
        print(self.name.title() + " rolled over!")

my_dog = Dog('peter', 10)
my_dog.sit()
my_dog.roll_over()

Peter is now sitting.
Peter rolled over!

class Dog():
    
    
    def __init__(self, name, age):
        self.name = name
        self.age = age
        
    def sit(self):
        print(self.name.title() + " is now sitting.")
        
    def roll_over(self):
        print(self.name.title() + " rolled over!")

my_dog = Dog('peter', 10)
your_dog = Dog('lucy', 6)

print("My dog's name is " + my_dog.name.title() + ".")
print("My dog is " + str(my_dog.age) + " years old.")
my_dog.sit()
my_dog.roll_over()

print("
Your dog's name is " + your_dog.name.title() + ".")
print("Your dog is " + str(your_dog.age) + " years old.")
your_dog.sit()
your_dog.roll_over()

My dog's name is Peter.
My dog is 10 years old.
Peter is now sitting.
Peter rolled over!

Your dog's name is Lucy.
Your dog is 6 years old.
Lucy is now sitting.
Lucy rolled over!

#使用类和实例
修改实例的属性

#Car类
class Car():
    def __init__(self, make, model, year):
        self.make = make
        self.model = model
        self.year = year
    
    def get_descriptive_name(self):
        long_name = str(self.year) + ' ' + self.make + ' ' + self.model
        return long_name.title()

my_new_car = Car('audi', 'a4', 2016)
print(my_new_car.get_descriptive_name())

2016 Audi A4

#给属性指定默认值
class Car():
    def __init__(self, make, model, year):
        self.make = make
        self.model = model
        self.year = year
        self.odometer_reading = 0
        
    def get_descriptive_name(self):
        long_name = str(self.year) + ' ' + self.make + ' ' + self.model
        return long_name.title()
    
    def read_odometer(self):
        print("This car has " + str(self.odometer_reading) + " miles on it.")
        
my_new_car = Car('audi', 'a4', 2016)
print(my_new_car.get_descriptive_name())
my_new_car.read_odometer()

2016 Audi A4
This car has 0 miles on it.

#修改属性的值
#直接修改
class Car():
    def __init__(self, make, model, year):
        self.make = make
        self.model = model
        self.year = year
        self.odometer_reading = 0
        
    def get_descriptive_name(self):
        long_name = str(self.year) + ' ' + self.make + ' ' + self.model
        return long_name.title()
    
    def read_odometer(self):
        print("This car has " + str(self.odometer_reading) + " miles on it.")
        
my_new_car = Car('audi', 'a4', 2016)
print(my_new_car.get_descriptive_name())
my_new_car.odometer_reading = 23
my_new_car.read_odometer()

2016 Audi A4
This car has 23 miles on it.

#通过方法修改属性的值
class Car():
    def __init__(self, make, model, year):
        self.make = make
        self.model = model
        self.year = year
        self.odometer_reading = 0
        
    def get_descriptive_name(self):
        long_name = str(self.year) + ' ' + self.make + ' ' + self.model
        return long_name.title()
    
    def read_odometer(self):
        print("This car has " + str(self.odometer_reading) + " miles on it.")
    
    def update_odometer(self, mileage):
        self.odometer_reading = mileage
        
my_new_car = Car('audi', 'a4', 2016)
print(my_new_car.get_descriptive_name())
my_new_car.update_odometer(23)
my_new_car.read_odometer()

2016 Audi A4
This car has 23 miles on it.

class Car():
    def __init__(self, make, model, year):
        self.make = make
        self.model = model
        self.year = year
        self.odometer_reading = 0
        
    def get_descriptive_name(self):
        long_name = str(self.year) + ' ' + self.make + ' ' + self.model
        return long_name.title()
    
    def read_odometer(self):
        print("This car has " + str(self.odometer_reading) + " miles on it.")
    
    def update_odometer(self, mileage):
        if mileage >= self.odometer_reading:
            self.odometer_reading = mileage
        else:
            print("You can't roll back an odometer!") 

#通过方法对属性的值进行递增
class Car():
    def __init__(self, make, model, year):
        self.make = make
        self.model = model
        self.year = year
        self.odometer_reading = 0
        
    def get_descriptive_name(self):
        long_name = str(self.year) + ' ' + self.make + ' ' + self.model
        return long_name.title()
    
    def read_odometer(self):
        print("This car has " + str(self.odometer_reading) + " miles on it.")
    
    def update_odometer(self, mileage):
        if mileage >= self.odometer_reading:
            self.odometer_reading = mileage
        else:
            print("You can't roll back an odometer!") 
            
    def increment_odometer(self, miles):
        self.odometer_reading += miles
        
my_used_car = Car('subaru', 'outback', 2013)
print(my_used_car.get_descriptive_name())

my_used_car.update_odometer(23500)
my_used_car.read_odometer()

my_used_car.increment_odometer(100)
my_used_car.read_odometer()

2013 Subaru Outback
This car has 23500 miles on it.
This car has 23600 miles on it.

'''
继承
使用情形：要编写的类是另一个现成类的特殊版本。
一个类继承另一个类时，将自动获得另一个类的所有属性和方法；
原有的类称为父类，新类称为子类；子类继承了父类的多有属性和方法，
同时还可以定义自己的属性和方法。
'''

#子类的方法__init()__
#父类汽车
class Car():
    def __init__(self, make, model, year):
        self.make = make
        self.model = model
        self.year = year
        self.odometer_reading = 0
        
    def get_descriptive_name(self):
        long_name = str(self.year) + ' ' + self.make + ' ' + self.model
        return long_name.title()
    
    def read_odometer(self):
        print("This car has " + str(self.odometer_reading) + " miles on it.")
    
    def update_odometer(self, mileage):
        if mileage >= self.odometer_reading:
            self.odometer_reading = mileage
        else:
            print("You can't roll back an odometer!") 
            
    def increment_odometer(self, miles):
        self.odometer_reading += miles
        
#子类电动汽车
class ElectricCar(Car):
    def __init__(self, make, model, year):
        #super()建立父类与子类之间的联系，调用父类的方法__init__()，让ElectricCar包含父类的所有属性，父类也称为超类。
        super().__init__(make, model, year)
        
my_tesla = ElectricCar('tesla', 'model s', 2016)
print(my_tesla.get_descriptive_name())

2016 Tesla Model S

#给子类定义属性和方法
#子类电动汽车
class ElectricCar(Car):
    def __init__(self, make, model, year):
        #super()建立父类与子类之间的联系，调用父类的方法__init__()，让ElectricCar包含父类的所有属性，父类也称为超类。
        super().__init__(make, model, year)
        self.battery_size = 70
        
    def describe_battery(self):
        print("This car has a " + str(self.battery_size) + "-KWh battery")

my_tesla = ElectricCar('tesla', 'model s', 2016)
print(my_tesla.get_descriptive_name())
my_tesla.describe_battery()

2016 Tesla Model S
This car has a 70-KWh battery
#重写父类的方法
'''
父类中的方法，不符合子类模拟的实物的行为，都可以对其进行重写。
可在子类中定义一个与要重写的父类的方法同名的方法。
'''

#将实例用作属性
'''
可以将大型类拆分成多个协同工作的小类
'''
class Battery():
    def __init__(self, battery_size = 70):
        self.battery_size = battery_size
        
    def describe_battery(self):
        print("This car has a " + str(self.battery_size) + "-KWh battery")

class ElectricCar(Car):
    def __init__(self, make, model, year):
        super().__init__(make, model, year)
        #创建一个新的Battery实例，并将该实例存储在属性self.battery中
        self.battery = Battery()
        
my_tesla = ElectricCar('tesla', 'model s', 2016)
print(my_tesla.get_descriptive_name())
my_tesla.battery.describe_battery()#注意这里！在my_tesla中查找属性battery，并对存储在该属性中的Battery实例调用方法describe_battery()

2016 Tesla Model S
This car has a 70-KWh battery

class Battery():
    def __init__(self, battery_size = 85):
        self.battery_size = battery_size
        
    def describe_battery(self):
        print("This car has a " + str(self.battery_size) + "-KWh battery")
        
    def get_range(self):
        if self.battery_size == 70:
            range = 240
        elif self.battery_size == 85:
            range = 270
            
        message = "This car can go approximately " + str(range) + " miles on a full charge."
        print(message)
        
class ElectricCar(Car):
    def __init__(self, make, model, year):
        super().__init__(make, model, year)
        #创建一个新的Battery实例，并将该实例存储在属性self.battery中
        self.battery = Battery()
        
my_tesla = ElectricCar('tesla', 'model s', 2016)
print(my_tesla.get_descriptive_name())
my_tesla.battery.describe_battery()
my_tesla.battery.get_range()

2016 Tesla Model S
This car has a 85-KWh battery
This car can go approximately 270 miles on a full charge.

#导入类 将类存储在模块中，在主程序中导入所需的模块
#导入单个类 car.py
class Car():
    def __init__(self, make, model, year):
        self.make = make
        self.model = model
        self.year = year
        self.odometer_reading = 0
        
    def get_descriptive_name(self):
        long_name = str(self.year) + ' ' + self.make + ' ' + self.model
        return long_name.title()
    
    def read_odometer(self):
        print("This car has " + str(self.odometer_reading) + " miles on it.")
    
    def update_odometer(self, mileage):
        if mileage >= self.odometer_reading:
            self.odometer_reading = mileage
        else:
            print("You can't roll back an odometer!") 
            
    def increment_odometer(self, miles):
        self.odometer_reading += miles

#my_car.py
from car import Car#打开模块car，导入其中的Car类

my_new_car = Car('audi', 'a4', 2016)
print(my_new_car.get_descriptive_name())

my_new_car.odometer_reading = 23
my_new_car.read_odometer()

2016 Audi A4
This car has 23 miles on it.

#在一个模块中存储多个类 car.py
class Car():
    def __init__(self, make, model, year):
        self.make = make
        self.model = model
        self.year = year
        self.odometer_reading = 0
        
    def get_descriptive_name(self):
        long_name = str(self.year) + ' ' + self.make + ' ' + self.model
        return long_name.title()
    
    def read_odometer(self):
        print("This car has " + str(self.odometer_reading) + " miles on it.")
    
    def update_odometer(self, mileage):
        if mileage >= self.odometer_reading:
            self.odometer_reading = mileage
        else:
            print("You can't roll back an odometer!") 
            
    def increment_odometer(self, miles):
        self.odometer_reading += miles
        
        
class Battery():
    def __init__(self, battery_size = 85):
        self.battery_size = battery_size
        
    def describe_battery(self):
        print("This car has a " + str(self.battery_size) + "-KWh battery")
        
    def get_range(self):
        if self.battery_size == 70:
            range = 240
        elif self.battery_size == 85:
            range = 270
            
        message = "This car can go approximately " + str(range) + " miles on a full charge."
        print(message)
        
        
class ElectricCar(Car):
    def __init__(self, make, model, year):
        super().__init__(make, model, year)
        self.battery = Battery()

#my_electric_car.py
from car import ElectricCar

my_tesla = ElectricCar('tesla', 'model s', 2016)

my_tesla.battery.describe_battery()
my_tesla.battery.get_range()

This car has a 85-KWh battery
This car can go approximately 270 miles on a full charge.

#从一个模块中导入多个类
#my_cars.py
from car import Car, ElectricCar

my_beetle = Car('volkswagen', 'beetle', 2016)
print(my_beetle.get_descriptive_name())

my_tesla = ElectricCar('tesla', 'model s', 2016)
print(my_tesla.get_descriptive_name())

2016 Volkswagen Beetle
2016 Tesla Model S

#导入整个模块 使用句点表示法访问需要的类
#my_cars.py
import car

my_beetle = car.Car('volkswagen', 'beetle', 2016)
print(my_beetle.get_descriptive_name())

my_tesla = car.ElectricCar('tesla', 'model s', 2016)
print(my_tesla.get_descriptive_name())

2016 Volkswagen Beetle
2016 Tesla Model S

#导入模块中的所有类
from module_name import*

#在一个模块中导入另一个模块
#electric_car.py
from car import Car#将Car类导入该模块中
class Battery():
    def __init__(self, battery_size = 85):
        self.battery_size = battery_size
        
    def describe_battery(self):
        print("This car has a " + str(self.battery_size) + "-KWh battery")
        
    def get_range(self):
        if self.battery_size == 70:
            range = 240
        elif self.battery_size == 85:
            range = 270
            
        message = "This car can go approximately " + str(range) + " miles on a full charge."
        print(message)
        
        
class ElectricCar(Car):
    def __init__(self, make, model, year):
        super().__init__(make, model, year)
        self.battery = Battery()        

#my_car.py
from car import Car
from electric_car import ElectricCar

my_beetle = Car('volkswagen', 'beetle', 2016)
print(my_beetle.get_descriptive_name())

my_tesla = ElectricCar('tesla', 'model s', 2016)
print(my_tesla.get_descriptive_name())

2016 Volkswagen Beetle
2016 Tesla Model S

#python标准库
'''
python标准库是一组模块，安装的python都包含。
OrderedDict
记录了键值对的添加顺序
'''
from collections import OrderedDict
favorite_languages = OrderedDict()

favorite_languages['jen'] = 'python' 
favorite_languages['sarah'] = 'c' 
favorite_languages['edward'] = 'ruby' 
favorite_languages['phil'] = 'python'

for name, language in favorite_languages.items():
    print(name.title() + "'s favorite language is " + language.title() + '.')

Jen's favorite language is Python.
Sarah's favorite language is C.
Edward's favorite language is Ruby.
Phil's favorite language is Python.