python效能對比

2021-09-22 13:30:30 字數 2507 閱讀 3605

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#1

#

-*- coding:utf8-*-

import

datetime

road_nodes ={}

for i in range(5000000):

road_nodes[i] =

beg_time =datetime.datetime.now()

for key, val in

road_nodes.items():

pass

end_time =datetime.datetime.now()

print

"time_scan:

", end_time - beg_time

耗時1

2

$python com_1.py

time_scan: 0:00:17.126098

#2

#

-*- coding:utf8-*-

import

datetime

road_nodes =

for i in range(5000000):

beg_time =datetime.datetime.now()

for key in

road_nodes:

pass

end_time =datetime.datetime.now()

print

"time_scan:

", end_time - beg_time

耗時1

2

$python com_2.py

time_scan: 0:00:00.325304

#3

#

-*- coding:utf8-*-

import

datetime

road_nodes ={}

for i in range(5000000):

road_nodes[i] =

beg_time =datetime.datetime.now()

for key in

road_nodes:

pass

end_time =datetime.datetime.now()

print

"time_scan:

", end_time - beg_time

耗時1

2

$python  com_3.py

time_scan: 0:00:00.359197

總結只對於字典key的遍歷,用for key in dic方式  

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#1

from datetime import

datetime

a =for i in range(50000):

aim_list =

for i in range(1000000):

beg_time =datetime.now()

for key in

a:

if key in

aim_list:

pass

end_time =datetime.now()

print

"scan:

", end_time - beg_time

執行1

2

$python draw.py

scan: 0:00:38.624985

#2  

from datetime import

datetime

a =for i in range(50000):

aim_list ={}

for i in range(1000000):

aim_list[i] =none

beg_time =datetime.now()

for key in

a:

if key in

aim_list:

pass

end_time =datetime.now()

print

"scan:

", end_time - beg_time

執行1

2

$python  draw2.py

scan: 0:00:00.014031

分析

巨大的差異由 aim_list型別導致,乙個是list,乙個是dict

for i in ***時,list是乙個個遍歷,效率是o(n);dict是直接找到,效率是o(1)。

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