'''生成器generator'''
# l = [x*x for x in range(11)]
# print(l)
t = (x*x for x in range(10))
print(t)
#使用next()方法,可以获取生成式中的下一个元素
print(next(t))
print(next(t))
#如果生成器中的元素已经取完了,则抛出stopIteration异常
print('----------------------------------------------------------')
g = (x*x for x in range(10))
for i in g:
print(i)
'''利用函数实现生成器'''
import time
def nature():
n = 1
while True:
'''return n 1、返回n的值;2、立即结束函数
yield n 1、返回n的值;2、立即暂停函数的执行
'''
# print(n)
yield n
n += 1
time.sleep(1)
g = nature()
print(next(g))
for e in g:
print(e)
time.sleep(1)
yield n
print(next(g))
'''
1 1 2 3 5 8 13
a = 0 b = 1 a+b=1; a = b b =a+b
a = 1 b = 1 a+b=2: a=b b =a+b
a = 2 b = 3 a+b=3; a=b b =a+b
a = 3 b = 5 a+b=8; a=b b=a+b
'''
print('----------------------------------------------------------')
def fib():
a,b = 0,1
while True:
yield b
t = a
a = b
b = t+b
#先计算赋值符号的右边,然后再赋值
a,b = b,a+b
time.sleep(1)
# f = fib()
# print(f)
# print(fib)
# for i in f:
# print(i)
# time.sleep(0.5)
from collections.abc import Iterable
print(isinstance(f,Iterable))
'''
高阶函数
函数名本质上就是一个指向该函数的变量
'''
print(abs(-5))
print(abs)
f=abs
print(f(-5))
abs = 7
print(abs)
'''
函数作为参数传入
一个函数A可以接收另一个函数B作为参数,我们把这个函数A称为高阶函数
'''
def add(x,y,f):
return f(x)+f(y)
print(add(3,4,f))
print(add(-3,4,f))
print(add(3,-4,f))
def g(x):
return x*x
print(add(3,4,g))
print(add(-3,4,g))
print(add(3,5,g))
#map()函数 高阶函数,g是一个新的函数,打出列表。函数是一个参数传入取值。
r = map(g,[1,2,3,4,5])
print(list(r))
'''函数作为返回值'''
def s(*args):
ss = 0
for arg in args:
ss += arg
return ss
print(s(1,2,3,4,5,6))
print(s(1,3,5,7,9))
'''
lazy_s()函数中定义了内部函数是s(),而s()函数中又引用了外部函数lazy_s()的参数arges
当lazy_s()函数返回函数s(),相关的参数和变量都已经保存在返回的函数中
我们把这种程序结构称为闭包closure'''
def lazy_s(*args):
#定义函数
def s ():
ss = 0
for arg in args:
ss += arg
return ss
return s
h = lazy_s(1,2,3,4)
print(h)
print(h())'''
def s ():
ss = 0
for arg in (1,2,3,4):
ss += arg
return ss
print(h)
print(h())
'''匿名函数lambda 表达式
匿名函数一般用于处理简单函数
'''
def g(x):
return x*x
r = map(g,[1,2,3,4,5,6])
print(list(r))
r = map(lambda x:x*x*x,[1,2,3,4,5,6])
print(list(r))
#匿名函数,也可以传多个参数
f = lambda x,y:x+y
print(f(2,3))
#用匿名函数重写
def is_odd(n):
return n%2 == 1
print(is_odd(3))
print(is_odd(2))
b = lambda n:n%2==1
print(b(4))
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