Python内置性能分析模块timeit

timeit模块

timeit模块可以用来测试一小段Python代码的执行速度。

class timeit.Timer(stmt='pass', setup='pass', timer=<timer function>)

Timer是测量小段代码执行速度的类。

stmt参数是要测试的代码语句（statement）；

setup参数是运行代码时需要的设置；

timer参数是一个定时器函数，与平台有关。

timeit.Timer.timeit(number=1000000)

Timer类中测试语句执行速度的对象方法。number参数是测试代码时的测试次数，默认为1000000次。方法返回执行代码的耗时，一个float类型的秒数。

举例

from timeit import Timer
# 直接代码
timer = Timer('print("a",end=",")')
print(timer.timeit())  # 默认100万次
timer = Timer('print(b,end=",")', 'b=2')
print(timer.timeit(number=5))  # 2,2,2,2,2,1.9295682939906674e-05
# 方法
def t():
print("t",end=",")

timer = Timer('t()', 'from __main__ import t')
print(timer.timeit(number=5)) #t,t,t,t,t,1.68324042667271e-05

# 比较列表几种添加元素的方法 + append insert 列表推导式 list()方法
def t1():
li = []
for i in range(1000):
li = li + [i]

def t2():
li = []
for i in range(10000):
li.append(i)

def t3():
li = []
for i in range(10000):
li.insert(0, i)

def t4():
li = [i for i in range(1000)]

def t5():
li = list(range(10000))

timer = Timer('t1()', 'from __main__ import t1')
print("+", timer.timeit(number=1000))
timer2 = Timer('t2()', 'from __main__ import t2')
print("append", timer2.timeit(number=1000))
timer3 = Timer('t3()', 'from __main__ import t3')
print("insert", timer3.timeit(number=1000))
timer4 = Timer('t4()', 'from __main__ import t4')
print("i for i in range", timer4.timeit(number=1000))
timer5 = Timer('t5()', 'from __main__ import t5')
print("list(range(10000)", timer5.timeit(number=1000))

# + 1.7064962406261983
# append 1.0096170504865387
# insert 24.474472632563394
# i for i in range 0.03823213773997125
# list(range(10000) 0.2569790843007844
# 列表推导式真是快，insert真是慢