python 第五天

class Dog():                类的首字母大写，定义中的括号是空的  类中的函数称为方法，先前学到的关于函数的知识也适用

"""一次模拟小狗的简单尝试"""          对函数加以说明
    def __init__(self, name, age):    初始化/initializ。这是特殊方法，每次创建实例都会自动运行。每个与类相关的方法都会自动传递实参self。它是实类本身的应用，让实类可以访问类的属性和方法
        """初始化属性name和age"""       对方法加以说明
        self.name = name              以self为前缀的变量可供类中所有方法使用，还可以通过类的任何实例来访问这些变量。可通过实例访问的变量成为属性
        self.age = age
    def sit(self):
        """模拟小狗被命令时蹲下"""
        print(self.name.title() + " is now sitting.")
    def roll_over(self):
        """模拟小狗被命令时打滚"""
        print(self.name.title() + " rolled over!")

my_dog = Dog(‘willie‘, 6)            方法__init__()并未显式地包含return语句，但Python自动返回一个表示这条小狗的实例。将这个实例存储在变量my_dog 中
my_dog.name                          访问属性使用句点表示法
my_dog.sit()                         使用句点访问法调用类中的任何方法

class Car():
    def __init__(self, make, model, year):
        """初始化描述汽车的属性"""
        self.make = make
        self.model = model
        self.year = year
        self.odometer_reading = 0        注意这里
    def get_descriptive_name(self):
        --snip--
    def read_odometer(self):
        """打印一条指出汽车里程的消息"""
        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()

my_new_car.odometer_reading = 23

class Car():
    --snip--
    def update_odometer(self, mileage):       与上面相比，这里添加了一个方法，在内部进行更新
        """将里程表读数设置为指定的值"""
        self.odometer_reading = mileage

class Car():
    --snip--
    def update_odometer(self, mileage):
        --snip--
    def increment_odometer(self, miles):      这里使用方法来对属性值递增
        """将里程表读数增加指定的量"""
        self.odometer_reading += miles

class Car():              创建子类时，父类必须包含在当前文件中，且位于子类前面
    """一次模拟汽车的简单尝试"""
    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 ElectricCar(Car):    定义子类时，必须在括号内指定父类的方法。方法__init__() 接受创建Car 实例所需的信息

"""电动汽车的独特之处"""
    def __init__(self, make, model, year):
    """初始化父类的属性"""
        super().__init__(make, model, year)   super（）是一个特殊函数，将父类和子类关联起来

class Car():
    --snip--class Battery():
    """一次模拟电动汽车电瓶的简单尝试"""    def __init__(self, battery_size=70):
        """初始化电瓶的属性"""
        self.battery_size = battery_size
    def describe_battery(self):
        """打印一条描述电瓶容量的消息"""
        print("This car has a " + str(self.battery_size) + "-kWh battery.")

class ElectricCar(Car):
    """电动汽车的独特之处"""
    def __init__(self, make, model, year):
        """初始化父类的属性，再初始化电动汽车特有的属性"""
        super().__init__(make, model,year)
        self.battery = Battery()

from car import Car

from car import Car, ElectricCar

import car
my_beetle = car.Car(‘volkswagen‘, ‘beetle‘, 2016)

from module_name import *

"""一组可用于表示电动汽车的类"""
from car import Car
class Battery():
    --snip--
class ElectricCar(Car):
    --snip--

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‘, ‘roadster‘, 2016)
print(my_tesla.get_descriptive_name())

from random import randint             生成一个[1,3]范围内的随机数
x = randint(1, 6)

temp_str = ‘this is a test‘
print(temp_str.replace(‘is‘,‘IS‘)
print(temp_str)

>>>thIS IS a test
>>>this is a test

with open(‘pi_digits.txt‘) as file_object:
    contents = file_object.read()
    print(contents)

with open(‘pi_digits.txt‘) as file_object:              
    contents = file_object.read()
    print(contents.rstrip())            Python方法rstrip()删除字符串末尾的空白。

with open(‘text_files\filename.txt‘) as file_object:

file_path = ‘C:\Users\ehmatthes\other_files\text_files\filename.txt‘
with open(file_path) as file_object:

filename = ‘pi_digits.txt‘
with open(filename) as file_object:
    for line in file_object:
        print(line.rstrip())

filename = ‘pi_digits.txt‘
with open(filename) as file_object:
    lines = file_object.readlines()    方法readlines()从文件中读取每一行，并将其存储在一个列表中
for line in lines:
    print(line.rstrip())    

filename = ‘pi_digits.txt‘
with open(filename) as file_object:
    lines = file_object.readlines()
pi_string = ‘‘
for line in lines:
    pi_string += line.rstrip()

print(pi_string)
print(len(pi_string))

filename = ‘programming.txt‘
with open(filename, ‘w‘) as file_object:
    file_object.write("I love programming.")

filename = ‘programming.txt‘
with open(filename, ‘w‘) as file_object:
    file_object.write("I love programming.\n")
    file_object.write("I love creating new games.\n")

filename = ‘programming.txt‘
with open(filename, ‘a‘) as file_object:
    file_object.write("I also love finding meaning in large datasets.\n")
    file_object.write("I love creating apps that can run in a browser.\n")