python效能對比

#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

$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

$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

$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　　

#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

$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

$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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