python前加r

from django.conf.urls.defaults import *
from mysite.views import hello, current_datetime, hours_ahead
urlpatterns = patterns
('', (r'^hello/$', hello), (r'^time/$', current_datetime), (r'^time/plus/(\d{1,2})/$', hours_ahead), )
加r表示后面的是普通字符，不发生转义主要在\n  就是\n而不是换行

详见日志http://blog.csdn.net/zhangxinrun/article/details/8124333