百度飞桨领航团零基础Python速成营 课程总结5
课程链接 https://aistudio.baidu.com/aistudio/course/introduce/7073
飞桨官网 https://www.paddlepaddle.org.cn/
推荐学习网站 https://www.runoob.com/python3/python3-tutorial.html
目录
课节5：Python面向对象(下)
继承
-
定义：
class 子类名(父类名)：-
情况1，如果子类有新增的属性，那么需要在子类__init方法中，调用父类的__init__
-
情况2，如果子类没有新增的属性,子类不需要写__init__方法
-
-
使用：对象名 = 子类名(参数)
-
继承的好处：代码重用，升级功能（重写），新增功能（新的方法）
# 读取文件
def get_coach_data(filename):
with open(filename) as f:
line = f.readline()
return line.strip().split(',')
#定义类
class Athlete:
def __init__(self,a_name,a_dob=None,a_times=[]):
self.name = a_name
self.dob = a_dob
self.times = a_times
def top3(self):
return sorted(set([self.sanitize(t) for t in self.times]))[0:3]
def sanitize(self,time_string):
if '-' in time_string:
splitter = '-'
elif ':' in time_string:
splitter = ':'
else:
return (time_string)
(mins,secs) = time_string.split(splitter)
return (mins+'.'+secs)
#定义橄榄球员类
class Rugby(Athlete):
def __init__(self,a_name,a_bod,a_squat,a_times):
#调用父类__init__
Athlete.__init__(self,a_name,a_bod,a_times)
#深蹲次数
self.squat = a_squat
# 继承后下面两个函数就在Rugby类中，只是看不到而已
# def top3(self):
# return sorted(set([self.sanitize(t) for t in self.times]))[0:3]
# def sanitize(self,time_string):
# if '-' in time_string:
# splitter = '-'
# elif ':' in time_string:
# splitter = ':'
# else:
# return (time_string)
# (mins,secs) = time_string.split(splitter)
# return (mins+'.'+secs)
loren = get_coach_data('mywork/loren.txt')
rugby = Rugby(loren.pop(0),loren.pop(0),loren.pop(0),loren)
print('姓名：%s,生日：%s,深蹲：%s个,最块的3次成绩：%s' %(rugby.name,rugby.dob,rugby.squat,rugby.top3()))
输出：
姓名：2011-11-3,生日：270,深蹲：3.59个,最块的3次成绩：['3.11', '3.23', '4.10']
方法重写
- 子类方法与父类方法完全相同，子类若重写了父类的方法，则子类对象调用方法时就是调用的自己类中重新的方法。
# 例1 选取最慢3次
class Rugby(Athlete):
def __init__(self,a_name,a_bod,a_squat,a_times):
Athlete.__init__(self,a_name,a_bod,a_times)
self.squat = a_squat
def top3(self):
return sorted([self.sanitize(t) for t in self.times])[-3:]
loren = get_coach_data('mywork/loren.txt')
rugby = Rugby(loren.pop(0),loren.pop(0),loren.pop(0),loren)
print('姓名：%s,生日：%s,深蹲：%s个,最慢的3次成绩：%s' %(rugby.name,rugby.dob,rugby.squat,rugby.top3()))
输出：
姓名：2011-11-3,生日：270,深蹲：3.59个,最慢的3次成绩：['4.11', '4.21', '4.21']
# 例2 其他运动员选取
class OtherAthlete(Athlete):
def __init__(self,a_name,a_bod,a_squat,a_times):
Athlete.__init__(self,a_name,a_bod,a_times)
self.squat = a_squat
def top3(self):
return sorted([self.sanitize(t) for t in self.times])[0:3]
mark = get_coach_data('mywork/mark.txt')
mark = OtherAthlete(mark.pop(0),mark.pop(0),mark.pop(0),mark)
print('姓名：%s,生日：%s,深蹲：%s个,最快的3次成绩：%s' %(mark.name,mark.dob,mark.squat,mark.top3()))
输出：
姓名：mark,生日：2010-2-4,深蹲：300个,最快的3次成绩：['3.11', '3.11', '3.23']
多态
- 多态性：一个事物多种形态
- 优点：减少重复代码，分离经常改变的代码与不经常改变的代码，使得代码可维护性提高。
方法重写：
# 更多球员选取
mark1 = get_coach_data('mywork/mark.txt')
mark2 = get_coach_data('mywork/mark1.txt')
mark3 = get_coach_data('mywork/mark2.txt')
mark1 = OtherAthlete(mark1.pop(0),mark1.pop(0),mark1.pop(0),mark1)
mark2 = OtherAthlete(mark2.pop(0),mark2.pop(0),mark2.pop(0),mark2)
mark3 = OtherAthlete(mark3.pop(0),mark3.pop(0),mark3.pop(0),mark3)
print('姓名：%s,生日：%s,深蹲：%s个,最快的3次成绩：%s' %(mark1.name,mark1.dob,mark1.squat,mark1.top3()))
print('姓名：%s,生日：%s,深蹲：%s个,最快的3次成绩：%s' %(mark2.name,mark2.dob,mark2.squat,mark2.top3()))
print('姓名：%s,生日：%s,深蹲：%s个,最快的3次成绩：%s' %(mark3.name,mark3.dob,mark3.squat,mark3.top3()))
输出：
姓名：mark,生日：2010-2-4,深蹲：300个,最快的3次成绩：['3.11', '3.11', '3.23']
姓名：mark,生日：2010-2-4,深蹲：111个,最快的3次成绩：['3.11', '3.11', '3.23']
姓名：mark,生日：2010-2-4,深蹲：222个,最快的3次成绩：['3.11', '3.11', '3.23']
loren = get_coach_data('mywork/loren.txt')
mark = get_coach_data('mywork/mark.txt')
loren = Rugby(loren.pop(0),loren.pop(0),loren.pop(0),loren)
mark = OtherAthlete(mark.pop(0),mark.pop(0),mark.pop(0),mark)
print(loren.name)
print(loren.dob)
print(loren.squat)
print(loren.top3())
print(mark.name)
print(mark.dob)
print(mark.squat)
print(mark.top3())
输出：
2011-11-3
270
3.59
['4.11', '4.21', '4.21']
mark
2010-2-4
300
['3.11', '3.11', '3.23']
使用多态：
# 更多球员选取
loren = get_coach_data('mywork/loren.txt')
mark = get_coach_data('mywork/mark.txt')
loren = Rugby(loren.pop(0),loren.pop(0),loren.pop(0),loren)
mark = OtherAthlete(mark.pop(0),mark.pop(0),mark.pop(0),mark)
def print_rugby(athlete):
print(athlete.name)
print(athlete.dob)
print(athlete.squat)
print(athlete.top3())
print_rugby(loren)
print_rugby(mark)
输出：
2011-11-3
270
3.59
['4.11', '4.21', '4.21']
mark
2010-2-4
300
['3.11', '3.11', '3.23']
#优化创建对象的代码
def obj_factory(name,filename):
with open(filename) as f:
line = f.readline()
templ = line.strip().split(',')
if name == 'r':
return Rugby(templ.pop(0),templ.pop(0),templ.pop(0),templ)
elif name == 'oa':
return OtherAthlete(templ.pop(0),templ.pop(0),templ.pop(0),templ)
oa = obj_factory('oa','mywork/mark.txt')
print(oa.name)
输出：
mark
多继承
class Father():
def __init__(self):
self.color = 'black'
def talk(self):
print("---爸爸的表达能力---")
class Mather():
def __init__(self):
self.height = 170
def smart(self):
print("---妈妈聪明的头脑---")
class Child(Father,Mather):
def __init__(self):
Father.__init__(self)
Mather.__init__(self)
child1 = Child()
child1.talk()
child1.smart()
print(child1.color)
print(child1.height)
输出：
---爸爸的表达能力---
---妈妈聪明的头脑---
black
170
模块化
import sys
# 将模块athlete.py添加到模块搜索路径
sys.path.append('mywork')
# import athlete
# print(dir(athlete))
# 导入athlete模块，使用athlete模块下的所有代码
from athlete import *
loren = get_coach_data('mywork/loren.txt')
mark = get_coach_data('mywork/mark.txt')
loren = Rugby(loren.pop(0),loren.pop(0),loren.pop(0),loren)
mark = OtherAthlete(mark.pop(0),mark.pop(0),mark.pop(0),mark)
def print_rugby(athlete):
print(athlete.name)
print(athlete.dob)
print(athlete.squat)
print(athlete.top3())
print_rugby(loren)
print_rugby(mark)
输出：
2011-11-3
270
3.59
['4.11', '4.21', '4.21']
mark
2010-2-4
300
['3.11', '3.11', '3.23']
装饰器
修改其他函数的功能的函数。
from functools import wraps
#使用了装饰器
def mylog(func):
@wraps(func)
def with_logging(*args):
print(func.__name__+" was called")
print(args)
return func(*args)
return with_logging
@mylog
def add(a,b):
print(a+b)
@mylog
def mins(a,b):
print(a-b)
@mylog
def mul(a,b):
print(a*b)
@mylog
def div(a,b):
print(a/b)
add(1,2)
mins(1,2)
mul(1,2)
div(1,2)
输出：
add was called
(1, 2)
3
mins was called
(1, 2)
-1
mul was called
(1, 2)
2
div was called
(1, 2)
0.5
作业五：Python面向对象(下)
（注：此次作业代码皆取自课件，参考课件即可完成。）
作业内容:
第一题
定义Rugby为Athlete的子类，并增加子类自己的属性squat。（5分）
def get_coach_data(filename):
with open(filename) as f:
line = f.readline()
return line.strip().split(',')
class Athlete:
def __init__(self,a_name,a_dob=None,a_times=[]):
self.name = a_name
self.dob = a_dob
self.times = a_times
def top3(self):
return sorted(set([self.sanitize(t) for t in self.times]))[0:3]
def sanitize(self,time_string):
if '-' in time_string:
splitter = '-'
elif ':' in time_string:
splitter = ':'
else:
return (time_string)
(mins,secs) = time_string.split(splitter)
return (mins+'.'+secs)
#代码1，定义Rugby类继承Athlete
class Rugby(Athlete):
def __init__(self,a_name,a_bod,a_squat,a_times):
#代码2，调用父类的构造方法，传递的参数为a_dob、a_times
Athlete.__init__(self,a_name,a_bod,a_times)
#代码3，将a_squat赋值给类属性squat
self.squat = a_squat
第二题
定义OtherAthlete类为Athlete类的子类，重写top3方法（允许重复的时间）。（5分）
#代码1，定义OtherAthlete类继承Athlete
class OtherAthlete(Athlete):
def __init__(self,a_name,a_bod,a_squat,a_times):
Athlete.__init__(self,a_name,a_bod,a_times)
self.squat = a_squat
#代码2，定义无参数top3函数，对self.times属性应用统一化和排序功能
def top3(self):
return sorted([self.sanitize(t) for t in self.times])[0:3]
第三题
定义print_rugby函数，以多态的方式调用子类属性和方法。（5分）
def get_coach_data(filename):
with open(filename) as f:
line = f.readline()
return line.strip().split(',')
loren = get_coach_data('mywork/loren.txt')
mark = get_coach_data('mywork/mark.txt')
loren = Rugby(loren.pop(0),loren.pop(0),loren.pop(0),loren)
mark = OtherAthlete(mark.pop(0),mark.pop(0),mark.pop(0),mark)
def print_rugby(athlete):
print(athlete.name)
#代码1，打印athlete的属性dob、squat和top3方法的返回值
print(athlete.dob)
print(athlete.squat)
print(athlete.top3())
#代码2，调用print_rugby函数，参数为loren
print_rugby(loren)
#代码3，调用print_rugby函数，参数为mark
print_rugby(mark)
输出：
loren
2011-11-3
270
['3.11', '3.23', '3.59']
mark
2010-2-4
300
['3.11', '3.11', '3.23']
第四题
有两个父类，一个Father，一个Mother，定义Child类共同继承这两个父类，子类调用父类的属性和方法 。（5分）
class Father():
def __init__(self):
self.color = 'black'
def talk(self):
print("---爸爸的表达能力---")
class Mother():
def __init__(self):
self.height = 170
def smart(self):
print("---妈妈聪明的头脑---")
#代码1，定义Child类继承Father和Mother
class Child(Father,Mother):
def __init__(self):
#代码2，调用Mother类的的__init__方法
Father.__init__(self)
Mother.__init__(self)
#代码3，创建Child类的对象child,调用无参数的构造方法
child1 = Child()
#代码4，通过child调用父类的smart方法
child1.smart()
#代码5，通过child打印父类的color属性
print(child1.color)
输出：
---妈妈聪明的头脑---
black
class Mother():
def init(self):
self.height = 170
def smart(self):
print("—妈妈聪明的头脑—")
#代码1，定义Child类继承Father和Mother
class Child(Father,Mother):
def init(self):
#代码2，调用Mother类的的__init__方法
Father.init(self)
Mother.init(self)
#代码3，创建Child类的对象child,调用无参数的构造方法
child1 = Child()
#代码4，通过child调用父类的smart方法
child1.smart()
#代码5，通过child打印父类的color属性
print(child1.color)
输出：
—妈妈聪明的头脑—
black