print(\'__next__\' in dir(range(12)))  #查看\'__next__\'是不是在range()方法执行之后内部是否有__next__
print(\'__iter__\' in dir(range(12)))  #查看\'__next__\'是不是在range()方法执行之后内部是否有__next__

from collections import Iterator
print(isinstance(range(100000000),Iterator))  #验证range执行之后得到的结果不是一个迭代器

range函数的返回值是一个可迭代对象

l=[1,2,3]

index=0
while index < len(l):
    print(l[index])
    index+=1

#要毛线for循环，要毛线可迭代，要毛线迭代器

def my_range():
    print(\'我是一个生成器函数\')
    n = 0
    while 1:
        yield n
        n += 1

def my_range2(start, stop):
    n = start
    while n < stop:
        yield n
        n += 1

def my_range3(start, stop, step):
    n = start
    while n < stop:
        yield n
        n += step

for i in my_range3(1, 10, 2):
    print(i)

import time


def tail(filename):
    f = open(filename)
    f.seek(0, 2) #从文件末尾算起
    while True:
        line = f.readline()  # 读取文件中新的文本行
        if not line:
            time.sleep(0.1)
            continue
        yield line

tail_g = tail(\'tmp\')
for line in tail_g:
    print(line)

生成器监听文件输入的例子

def eat(name):
    print(\'%s要开始吃了！\' % name)
    while 1:
        food = yield
        print(\'{}在吃{}\'.format(name, food))


a = eat(\'alex\')
a.__next__()  # 初始化，让函数暂停在yield处
a.send(\'包子\')  # send两个作用：1.给yield传值 2.继续执行函数
a.send(\'饺子\')

def averager():
    total = 0.0
    count = 0
    average = None
    while True:
        term = yield average
        total += term
        count += 1
        average = total/count


g_avg = averager()
next(g_avg)
print(g_avg.send(10))
print(g_avg.send(30))
print(g_avg.send(5))

计算移动平均值(1)

def init(func):  #在调用被装饰生成器函数的时候首先用next激活生成器
    def inner(*args,**kwargs):
        g = func(*args,**kwargs)
        next(g)
        return g
    return inner

@init
def averager():
    total = 0.0
    count = 0
    average = None
    while True:
        term = yield average
        total += term
        count += 1
        average = total/count


g_avg = averager()
# next(g_avg)   在装饰器中执行了next方法
print(g_avg.send(10))
print(g_avg.send(30))
print(g_avg.send(5))

计算移动平均值(2)_预激协程的装饰器

def gen1():
    for c in \'AB\':
        yield c
    for i in range(3):
        yield i

print(list(gen1()))

def gen2():
    yield from \'AB\'
    yield from range(3)

print(list(gen2()))

yield from

#老男孩由于峰哥的强势加盟很快走上了上市之路,alex思来想去决定下几个鸡蛋来报答峰哥

egg_list=[\'鸡蛋%s\' %i for i in range(10)] #列表解析

#峰哥瞅着alex下的一筐鸡蛋,捂住了鼻子,说了句:哥,你还是给我只母鸡吧,我自己回家下

laomuji=(\'鸡蛋%s\' %i for i in range(10))#生成器表达式
print(laomuji)
print(next(laomuji)) #next本质就是调用__next__
print(laomuji.__next__())
print(next(laomuji))

峰哥与alex的故事

sum(x ** 2 for x in range(4))

sum([x ** 2 for x in range(4)]) 

def demo():
    for i in range(4):
        yield i

g=demo()

g1=(i for i in g)
g2=(i for i in g1)

print(list(g1))
print(list(g2))

面试题1

def add(a, b):
    return a + b


def func():
    for i in range(4):
        yield i


g = func()
for n in [1, 10]:
    g = (add(n, i) for i in g)


print(list(g))

面试题2

>>> abs(1)
1
>>> abs(-1)         # 求绝对值
1
>>> round(1.234,2)
1.23
>>> round(1.269,2)  # 四舍五入
1.27
>>> sum([1,2,3,4])
10
>>> sum((1,3,5,7))  # 接收数字组成的元组/列表
16

>>> def func():pass  
>>> callable(func)   # 判断一个变量是否可以调用 函数可以被调用
True
>>> a = 123          # 数字类型a不能被调用
>>> callable(a)
False
>>> chr(97)          # 将一个数字转换成一个字母
\'a\'
>>> chr(65)
\'A\'
>>> dir(123)         # 查看数字类型中含有哪些方法
[\'__abs__\', \'__add__\', \'__and__\', \'__bool__\', \'__ceil__\', \'__class__\', \'__delattr__\', \'__dir__\', \'__divmod__\', \'__doc__\', \'__eq__\', \'__float__\', \'__floor__\', \'__floordiv__\', \'__format__\', \'__ge__\', \'__getattribute__\', \'__getnewargs__\', \'__gt__\', \'__hash__\', \'__index__\', \'__init__\', \'__init_subclass__\', \'__int__\', \'__invert__\', \'__le__\', \'__lshift__\', \'__lt__\', \'__mod__\', \'__mul__\', \'__ne__\', \'__neg__\', \'__new__\', \'__or__\', \'__pos__\', \'__pow__\', \'__radd__\', \'__rand__\', \'__rdivmod__\', \'__reduce__\', \'__reduce_ex__\', \'__repr__\', \'__rfloordiv__\', \'__rlshift__\', \'__rmod__\', \'__rmul__\', \'__ror__\', \'__round__\', \'__rpow__\', \'__rrshift__\', \'__rshift__\', \'__rsub__\', \'__rtruediv__\', \'__rxor__\', \'__setattr__\', \'__sizeof__\', \'__str__\', \'__sub__\', \'__subclasshook__\', \'__truediv__\', \'__trunc__\', \'__xor__\', \'bit_length\', \'conjugate\', \'denominator\', \'from_bytes\', \'imag\', \'numerator\', \'real\', \'to_bytes\']
>>> dir(\'abc\')
[\'__add__\', \'__class__\', \'__contains__\', \'__delattr__\', \'__dir__\', \'__doc__\', \'__eq__\', \'__format__\', \'__ge__\', \'__getattribute__\', \'__getitem__\', \'__getnewargs__\', \'__gt__\', \'__hash__\', \'__init__\', \'__init_subclass__\', \'__iter__\', \'__le__\', \'__len__\', \'__lt__\', \'__mod__\', \'__mul__\', \'__ne__\', \'__new__\', \'__reduce__\', \'__reduce_ex__\', \'__repr__\', \'__rmod__\', \'__rmul__\', \'__setattr__\', \'__sizeof__\', \'__str__\', \'__subclasshook__\', \'capitalize\', \'casefold\', \'center\', \'count\', \'encode\', \'endswith\', \'expandtabs\', \'find\', \'format\', \'format_map\', \'index\', \'isalnum\', \'isalpha\', \'isascii\', \'isdecimal\', \'isdigit\', \'isidentifier\', \'islower\', \'isnumeric\', \'isprintable\', \'isspace\', \'istitle\', \'isupper\', \'join\', \'ljust\', \'lower\', \'lstrip\', \'maketrans\', \'partition\', \'replace\', \'rfind\', \'rindex\', \'rjust\', \'rpartition\', \'rsplit\', \'rstrip\', \'split\', \'splitlines\', \'startswith\', \'strip\', \'swapcase\', \'title\', \'translate\', \'upper\', \'zfill\']

>>> eval(\'1+2-3*4/5\')  # 执行字符串数据类型的代码并且将值返回
0.6000000000000001
>>> exec(\'print(123)\') # 执行字符串数据类型的代码但没有返回值
123

>>> enumerate([\'apple\',\'banana\'],1)   # 会给列表中的每一个元素拼接一个序号
<enumerate object at 0x113753fc0>
>>> list(enumerate([\'apple\',\'banana\'],1))
[(1, \'apple\'), (2, \'banana\')]

>>> max(1,2,3,)     # 求最小值
3
>>> min(2,1,3)      # 求最大值
1

>>> sorted([1, 4, 5, 12, 45, 67])  # 排序，并生成一个新的有序列表
[1, 4, 5, 12, 45, 67]

>>> sorted([1, 4, 5, 12, 45, 67], reverse=True)
[67, 45, 12, 5, 4, 1]

list1 = [
    {\'name\': \'Zoe\', \'age\': 30},
    {\'name\': \'Bob\', \'age\': 18},
    {\'name\': \'Tom\', \'age\': 22},
    {\'name\': \'Jack\', \'age\': 40},
]

ret = sorted(list1, key=lambda x: x[\'age\'])
print(ret)

# [{\'name\': \'Bob\', \'age\': 18}, {\'name\': \'Tom\', \'age\': 22}, {\'name\': \'Zoe\', \'age\': 30}, {\'name\': \'Jack\', \'age\': 40}]

>>> x = ["a", "b", "c"]
>>> y = [1, 2, 3]
>>> a = list(zip(x, y))  # 合包
>>> a
[(\'a\', 1), (\'b\', 2), (\'c\', 3)]
>>> b =list(zip(*a))  # 解包
>>> b
[(\'a\', \'b\', \'c\'), (1, 2, 3)]

>>> x = [1, 3, 5, 7, 9]
>>> y = [2, 4, 6, 8]
>>> for m, n in zip(x, y):
...   print(m, n)
... 
1 2
3 4
5 6
7 8

>>> from itertools import zip_longest
>>> x = [1, 3, 5, 7, 9]
>>> y = [2, 4, 6, 8]
>>> for m, n in zip_longest(x, y):
...   print(m, n)
... 
1 2
3 4
5 6
7 8
9 None

>>> keys = ["name", "age", "salary"]
>>> values = ["Andy", 18, 50]
>>> d = dict(zip(keys, values))
>>> d
{\'name\': \'Andy\', \'age\': 18, \'salary\': 50}

>>> l = [11, 22, 33, 44, 55]
>>> list(map(lambda x:x+100, l))
[111, 122, 133, 144, 155]

def my_map(func, seq):
    result = []
    for i in seq:
        result.append(func(i))
    return result

>>> def my_map(func, seq):
...     result = []
...     for i in seq:
...         result.append(func(i))
...     return result
... 
>>> l = [11, 22, 33, 44, 55]
>>> list(my_map(lambda x:x+100, l))
[111, 122, 133, 144, 155]

def my_map(func, seq):
    for i in seq:
        yield func(i)

>>> def my_map(func, seq):
...     for i in seq:
...         yield func(i)
... 
>>> l = [11, 22, 33, 44, 55]
>>> list(my_map(lambda x:x+100, l))
[111, 122, 133, 144, 155]

>>> pow(2, 10)
1024
>>> pow(3, 11)
177147
>>> pow(4, 12)
16777216
>>> list(map(pow, [2, 3, 4], [10, 11, 12]))
[1024, 177147, 16777216]

>>> l = [30, 11, 77, 8, 25, 65, 4]
>>> list(filter(lambda x: x>33, l))
[77, 65]

>>> x = [1, 2, 3, 5, 6]
>>> y = [2, 3, 4, 6, 7]
>>> list(filter(lambda a: a in y, x))
[2, 3, 6]

>>> from functools import reduce
>>> reduce(lambda x,y:x+y, [1, 2, 3, 4])
10

>>> from functools import reduce
>>> reduce(lambda x,y:x+y, range(1, 101))
5050

#这段代码
def func(x, y):
    return x + y#换成匿名函数
lambda x, y:x+y

请把以下函数变成匿名函数
def func(x, y):
    return x + y

l=[3,2,100,999,213,1111,31121,333]
print(max(l))

dic={\'k1\':10,\'k2\':100,\'k3\':30}


print(max(dic))
print(dic[max(dic,key=lambda k:dic[k])])

res = map(lambda x:x**2,[1,5,7,4,8])
for i in res:
    print(i)

输出
1
25
49
16
64

res = filter(lambda x:x>10,[5,8,11,9,15])
for i in res:
    print(i)

输出
11
15

#答案一
test = lambda t1,t2 :[{i:j} for i,j in zip(t1,t2)]
print(test(t1,t2))
#答案二
print(list(map(lambda t:{t[0]:t[1]},zip(t1,t2))))
#还可以这样写
print([{i:j} for i,j in zip(t1,t2)])

练习1-coding

1.下面程序的输出结果是：
d = lambda p:p*2
t = lambda p:p*3
x = 2
x = d(x)
x = t(x)
x = d(x)
print x

练习2

>>> from functools import reduce
>>> l = [30, 11, 77, 8, 25, 65, 4]
>>> reduce(lambda x,y: x if x > y else y, l)
77

>>> l = [30, 11, 77, 8, 25, 65, 4]
>>> list(map(lambda x: x+100 if x%2 else x, l))
[30, 111, 177, 8, 125, 165, 4]

def story():
    s = """
    从前有个山，山里有座庙，庙里有个老和尚在讲故事，
    讲的什么呢？
    """
    print(s)
    story()
    
story()

import sys
print(sys.getrecursionlimit())

import sys
print(sys.setrecursionlimit(100000))

修改递归最大深度

def tell(x):
    for i in x:
        if not isinstance(i, list):
            print(i)
        else:
            tell(i)
            
            
tell(list1)