python求时间差

转自：http://blog.sina.com.cn/s/blog_519ccabf01010ykx.html

1.python求时间差不能使用time()模块，eg：

t1 = time.ctime()

time.sleep(3)

t2 = time.ctime()

t = t2 - t1 ###会报错，不能相减

2.需要使用datetime模块，datetime模块比time模块更能更强。

d1 = datetime.datetime.now()

time.sleep(3)

d2 = datetime.datetime.now()

d = d2-d1 ###
产生的是 datetime.timedelta 对象

d.days 天

d.max 最大

d.microseconds 微秒

d.min 最小

d.resolution

d.seconds 秒

注： d1, d2 还可以格式化成正常的日期时间。

e.g:

t_now = str(d1) ###
t_now = '2012-02-17 12:49:04.828000' 精确到毫秒

t_now[:19] ##
秒级别 '2012-02-17 12:49:04'

t_now[:10] ##
日期级别 '2012-02-17'

可根据需要自己裁定

测试模块：

测试报告：

logs = Log.objects.order_by('-start_time')

d1 = datetime.datetime.now()

#logs = logs.order_by('start_time')

log_list = list(logs)

log_list.sort(key=operator.attrgetter('start_time'), reverse=False)

d2 = datetime.datetime.now()

d = d2 - d1

print d

0:00:00.811000

[12/Nov/2012 18:06:24] "GET /log/index/?_=1352714783865 HTTP/1.1" 200 10564

0:00:00.780000

[12/Nov/2012 18:06:43] "GET /log/index/?_=1352714802185 HTTP/1.1" 200 10564

0:00:00.764000

[12/Nov/2012 18:07:06] "GET /log/index/?_=1352714825224 HTTP/1.1" 200 10564

0:00:00.749000

[12/Nov/2012 18:07:07] "GET /log/index/?_=1352714827160 HTTP/1.1" 200 10564

0:00:00.780000

[12/Nov/2012 18:07:09] "GET /log/index/?_=1352714828683 HTTP/1.1" 200 10564

logs = Log.objects.order_by('-start_time')

d1 = datetime.datetime.now()

#logs = logs.order_by('start_time')

log_list = list(logs)

log_list.sort(key=operator.attrgetter('start_time'), reverse=True)

d2 = datetime.datetime.now()

d = d2 - d1

print d

0:00:00.780000

[12/Nov/2012 18:09:12] "GET /log/index/?_=1352714951344 HTTP/1.1" 200 10564

0:00:00.780000

[12/Nov/2012 18:09:48] "GET /log/index/?_=1352714987642 HTTP/1.1" 200 10564

0:00:00.764000

[12/Nov/2012 18:09:50] "GET /log/index/?_=1352714989233 HTTP/1.1" 200 10564

0:00:00.780000

[12/Nov/2012 18:09:51] "GET /log/index/?_=1352714990809 HTTP/1.1" 200 10564

0:00:00.795000

[12/Nov/2012 18:09:53] "GET /log/index/?_=1352714992482 HTTP/1.1" 200 10564

0:00:00.796000

[12/Nov/2012 18:09:55] "GET /log/index/?_=1352714994265 HTTP/1.1" 200 10564

logs = Log.objects.order_by('-start_time')

d1 = datetime.datetime.now()

logs = logs.order_by('start_time')

#log_list = list(logs)[0:10]

#log_list.sort(key=operator.attrgetter('start_time'), reverse=False)

d2 = datetime.datetime.now()

d = d2 - d1

print d

0:00:00

[12/Nov/2012 18:18:14] "GET /log/index/?_=1352715494293 HTTP/1.1" 200 10667

0:00:00

[12/Nov/2012 18:18:15] "GET /log/index/?_=1352715494940 HTTP/1.1" 200 10667

0:00:00

[12/Nov/2012 18:18:15] "GET /log/index/?_=1352715495661 HTTP/1.1" 200 10667

0:00:00

[12/Nov/2012 18:18:16] "GET /log/index/?_=1352715496335 HTTP/1.1" 200 10667

0:00:00

[12/Nov/2012 18:18:17] "GET /log/index/?_=1352715497517 HTTP/1.1" 200 10667