小练习2
1#测试函数执行时间的装饰器示例 import time def timing_func(fn): def wrapper(): start=time.time() fn() #执行传入的fn参数 stop=time.time() return (stop-start) return wrapper @timing_func def test_list_append(): lst=[] for i in range(0,100000): lst.append(i) @timing_func def test_list_compre(): [i for i in range(0,100000)] #列表生成式 a=test_list_append() c=test_list_compre() print("test list append time:",a) print("test list comprehension time:",c) print("append/compre:",round(a/c,3)) test list append time: 0.0219423770904541 test list comprehension time: 0.007980823516845703 append/compre: 2.749
2.统计异常出现次数和时间的装饰器
写一个装饰器,统计某个异常重复出现指定次数时,经历的时长。
import time import math def excepter(f): i = 0 t1 = time.time() def wrapper(): try: f() except Exception as e: nonlocal i i += 1 print(f'{e.args[0]}: {i}') t2 = time.time() if i == n: print(f'spending time:{round(t2-t1,2)}') return wrapper
3.定制递减迭代器
#编写一个迭代器,通过循环语句,实现对某个正整数的依次递减1,直到0.
class Descend(Iterator):
def __init__(self,N):
self.N=N
self.a=0
def __iter__(self):
return self
def __next__(self):
while self.a<self.N:
self.N-=1
return self.N
raise StopIteration
descend_iter=Descend(10)
print(list(descend_iter))
[9, 8, 7, 6, 5, 4, 3, 2, 1, 0]