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今天给大家分享一下在Python中创建列表的时间复杂度
import timeit
from timeit import Timer
#append方法创建列表
def test1():
li = []
for i in range(10000):
li.append(i)
#用+=的方法创建列表
def test2():
li = []
for i in range(10000):
li += [i]
#快速创建列表
def test3():
li = [i for i in range(10000)]
#用list方法创建列表
def test4():
li = list(range(10000))
#给列表头添加,创建列表
def test5():
for i in range(10000):
li = []
li.insert(0,i)
#用extend创建列表
def test6():
li = []
for i in range(10000):
li.extend([i])
timer1 = Timer("test1()","from __main__ import test1")
print("append:",timer1.timeit(1000))
timer2 = Timer("test2()","from __main__ import test2")
print("+:",timer2.timeit(1000))
timer3 = Timer("test3()","from __main__ import test3")
print("i for i in range(10000):",timer3.timeit(1000))
timer4 = Timer("test4()","from __main__ import test4")
print("list(range(10000)):",timer4.timeit(1000))
timer5 = Timer("test5()","from __main__ import test5")
print("insert:",timer5.timeit(1000))
timer6 = Timer("test6()","from __main__ import test6")
print("extend:",timer6.timeit(1000))
代码结果:append: 0.903441777
+: 1.0856896790000001
i for i in range(10000): 0.6145070609999999
list(range(10000)): 0.25812306100000004
insert: 1.5664304200000005
extend: 1.0411812350000007
可以看出,最快的是用list方法创建列表,而最慢的是用insert给头部添加创建列表,这关系到列表的底层创建,有兴趣的人可以了解了解,