python 列表类型不同操作的时间效率

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；

setup参数是运行代码需要的设置，第一个参数语句构建环境的导入语句；

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平均耗时，一个float类型的秒数。

list的操作测试

#python列表类型不同操作的时间效率

from timeit import Timer

def t1():
    l1 = []
    for i in range(1000):
        l1 += [i]

def t2():
    l2 = []
    for i in range(1000):
        l2.append(i)

def t3():
    l3 = [i for i in range(1000)]

def t4():
    l4 = list(range(1000))

def t5():
    l5 = []
    for i in range(1000):
        l5.extend([i])

def t6():
    l6 = []
    for i in range(1000):
        l6.insert(-1,i)

t11 = Timer("t1()","from __main__ import t1")
print("+",t11.timeit(number=1000),"seconds")

t22 = Timer("t2()","from __main__ import t2")
print("append",t22.timeit(number=1000),"seconds")

t33 = Timer("t3()","from __main__ import t3")
print("列表生成器[]",t33.timeit(number=1000),"seconds")

t44 = Timer("t4()","from __main__ import t4")
print("list(range)",t44.timeit(number=1000),"seconds")

t55 = Timer("t5()","from __main__ import t5")
print("extend",t55.timeit(number=1000),"seconds")

t66 = Timer("t6()","from __main__ import t6")
print("insert",t66.timeit(number=1000),"seconds")

运行结果：

+ 0.18604349519765948 seconds
append 0.08720970170491515 seconds
列表生成器[] 0.03744805873315149 seconds
list(range) 0.015047234072873672 seconds
extend 0.1769862267909631 seconds
insert 0.17517417577705496 seconds