python中查看程序运行的时间

import datetime 
start = datetime.datetime.now() 
run_function(): # do something 
end = datetime.datetime.now() 
print (end-start) 

方法2:

import time
start = time.time()
run_function()
end = time.time()

print str(end)

方法3:

start = time.clock()
run_function()
end = time.clock()

print str(end-start)