yield a triplet of expressions Expressions
yield expression
# x=yield 返回值
# def dog(name):
# print('道哥%s准备吃东西啦...' %name) # while True: # # x拿到的是yield接收到的值 # x = yield # x = '肉包子' # print('道哥%s吃了 %s' %(name,x)) # # # g=dog('alex') # g.send(None) # 等同于next(g) # # g.send(['一根骨头','aaa']) # # g.send('肉包子') # # g.send('一同泔水') # # g.close() # # g.send('1111') # 关闭之后无法传值 A triplet of expressions
Syntax: The value to return value if condition else condition if the conditions are not satisfied to be returned
x=1
y=2
# res=x if x > y else y
# print(res)
res=111111 if 'egon' == 'egon' else 2222222222
print(res)
Generative
# 1、列表生成式
l = ['alex_dsb', 'lxx_dsb', 'wxx_dsb', "xxq_dsb", 'egon']
# new_l=[]
# for name in l: # if name.endswith('dsb'): # new_l.append(name) # new_l=[name for name in l if name.endswith('dsb')] # new_l=[name for name in l] # print(new_l) # 把所有小写字母全变成大写 # new_l=[name.upper() for name in l] # print(new_l) # 把所有的名字去掉后缀_dsb # new_l=[name.replace('_dsb','') for name in l] # print(new_l) # 2、字典生成式 # keys=['name','age','gender'] # dic={key:None for key in keys} # print(dic) # items=[('name','egon'),('age',18),('gender','male')] # res={k:v for k,v in items if k != 'gender'} # print(res) # 3、集合生成式 # keys=['name','age','gender'] # set1={key for key in keys} # print(set1,type(set1)) # 4、生成器表达式 # g=(i for i in range(10) if i > 3) # ！！！！！！！！！！！强调！！！！！！！！！！！！！！！ # 此刻g内部一个值也没有 # print(g,type(g)) # print(next(g)) # print(next(g)) Application generator expressions
with open('笔记.txt', mode='rt', encoding='utf-8') as f: # 方式一： # res=0 # for line in f: # res+=len(line) # print(res) # 方式二： # res=sum([len(line) for line in f]) # print(res) # 方式三 ：效率最高 # res = sum((len(line) for line in f)) # 上述可以简写为如下形式 res = sum(len(line) for line in f) print(res)
Recursive function calls
A recursive definition
The recursive function: the function is a special form of nested calls, in particular: a function calling process has to call itself directly or indirectly
# 直接调用本身
# def f1():
# print('是我是我还是我') # f1() # f1() # 间接接调用本身 # def f1(): # print('===>f1') # f2() # # def f2(): # print('===>f2') # f1() # # f1() # 一段代码的循环运行的方案有两种 # 方式一：while、for循环 # while True: # print(1111) # print(2222) # print(3333) # 方式二：递归的本质就是循环： # def f1(): # print(1111) # print(2222) # print(3333) # f1() # f1() Second, the need to emphasize
Infinitely recursive call should not call it, must end in a recursive call to meet certain conditions
# def f1(n):
# if n == 10: # return # print(n) # n+=1 # f1(n) # # f1(0) Two-stage recursive
Back: call down layer by layer
Recursive: to meet certain conditions of the end, the end of the recursive call, and then return one level
# age(5) = age(4) + 10
# age(4) = age(3) + 10
# age(3) = age(2) + 10 # age(2) = age(1) + 10 # age(1) = 18 # def age(n): # if n == 1: # return 18 # return age(n-1) + 10 # # # res=age(5) # print(res) Applied recursively
l=[1,2,[3,[4,[5,[6,[7,[8,[9,10,11,[12,[13,]]]]]]]]]] def f1(list1): for x in list1: if type(x) is list: # 如果是列表，应该再循环、再判断,即重新运行本身的代码 f1(x) else: print(x) f1(l)yield expression
# x=yield 返回值
# def dog(name):
# print('道哥%s准备吃东西啦...' %name) # while True: # # x拿到的是yield接收到的值 # x = yield # x = '肉包子' # print('道哥%s吃了 %s' %(name,x)) # # # g=dog('alex') # g.send(None) # 等同于next(g) # # g.send(['一根骨头','aaa']) # # g.send('肉包子') # # g.send('一同泔水') # # g.close() # # g.send('1111') # 关闭之后无法传值 A triplet of expressions
Syntax: The value to return value if condition else condition if the conditions are not satisfied to be returned
x=1
y=2
# res=x if x > y else y
# print(res)
res=111111 if 'egon' == 'egon' else 2222222222
print(res)
Generative
# 1、列表生成式
l = ['alex_dsb', 'lxx_dsb', 'wxx_dsb', "xxq_dsb", 'egon']
# new_l=[]
# for name in l: # if name.endswith('dsb'): # new_l.append(name) # new_l=[name for name in l if name.endswith('dsb')] # new_l=[name for name in l] # print(new_l) # 把所有小写字母全变成大写 # new_l=[name.upper() for name in l] # print(new_l) # 把所有的名字去掉后缀_dsb # new_l=[name.replace('_dsb','') for name in l] # print(new_l) # 2、字典生成式 # keys=['name','age','gender'] # dic={key:None for key in keys} # print(dic) # items=[('name','egon'),('age',18),('gender','male')] # res={k:v for k,v in items if k != 'gender'} # print(res) # 3、集合生成式 # keys=['name','age','gender'] # set1={key for key in keys} # print(set1,type(set1)) # 4、生成器表达式 # g=(i for i in range(10) if i > 3) # ！！！！！！！！！！！强调！！！！！！！！！！！！！！！ # 此刻g内部一个值也没有 # print(g,type(g)) # print(next(g)) # print(next(g)) Application generator expressions
with open('笔记.txt', mode='rt', encoding='utf-8') as f: # 方式一： # res=0 # for line in f: # res+=len(line) # print(res) # 方式二： # res=sum([len(line) for line in f]) # print(res) # 方式三 ：效率最高 # res = sum((len(line) for line in f)) # 上述可以简写为如下形式 res = sum(len(line) for line in f) print(res)
Recursive function calls
A recursive definition
The recursive function: the function is a special form of nested calls, in particular: a function calling process has to call itself directly or indirectly
# 直接调用本身
# def f1():
# print('是我是我还是我') # f1() # f1() # 间接接调用本身 # def f1(): # print('===>f1') # f2() # # def f2(): # print('===>f2') # f1() # # f1() # 一段代码的循环运行的方案有两种 # 方式一：while、for循环 # while True: # print(1111) # print(2222) # print(3333) # 方式二：递归的本质就是循环： # def f1(): # print(1111) # print(2222) # print(3333) # f1() # f1() Second, the need to emphasize
Infinitely recursive call should not call it, must end in a recursive call to meet certain conditions
# def f1(n):
# if n == 10: # return # print(n) # n+=1 # f1(n) # # f1(0) Two-stage recursive
Back: call down layer by layer
Recursive: to meet certain conditions of the end, the end of the recursive call, and then return one level
# age(5) = age(4) + 10
# age(4) = age(3) + 10
# age(3) = age(2) + 10 # age(2) = age(1) + 10 # age(1) = 18 # def age(n): # if n == 1: # return 18 # return age(n-1) + 10 # # # res=age(5) # print(res) Applied recursively
l=[1,2,[3,[4,[5,[6,[7,[8,[9,10,11,[12,[13,]]]]]]]]]] def f1(list1): for x in list1: if type(x) is list: # 如果是列表，应该再循环、再判断,即重新运行本身的代码 f1(x) else: print(x) f1(l)A recursive definition
The recursive function: the function is a special form of nested calls, in particular: a function calling process has to call itself directly or indirectly
# 直接调用本身
# def f1():
# print('是我是我还是我') # f1() # f1() # 间接接调用本身 # def f1(): # print('===>f1') # f2() # # def f2(): # print('===>f2') # f1() # # f1() # 一段代码的循环运行的方案有两种 # 方式一：while、for循环 # while True: # print(1111) # print(2222) # print(3333) # 方式二：递归的本质就是循环： # def f1(): # print(1111) # print(2222) # print(3333) # f1() # f1() Second, the need to emphasize
Infinitely recursive call should not call it, must end in a recursive call to meet certain conditions
# def f1(n):
# if n == 10: # return # print(n) # n+=1 # f1(n) # # f1(0) Two-stage recursive
Back: call down layer by layer
Recursive: to meet certain conditions of the end, the end of the recursive call, and then return one level
# age(5) = age(4) + 10
# age(4) = age(3) + 10
# age(3) = age(2) + 10 # age(2) = age(1) + 10 # age(1) = 18 # def age(n): # if n == 1: # return 18 # return age(n-1) + 10 # # # res=age(5) # print(res) Applied recursively
l=[1,2,[3,[4,[5,[6,[7,[8,[9,10,11,[12,[13,]]]]]]]]]] def f1(list1): for x in list1: if type(x) is list: # 如果是列表，应该再循环、再判断,即重新运行本身的代码 f1(x) else: print(x) f1(l)