每天CookBook之Python-015

• groupby的使用

from operator import itemgetter
from itertools import groupby

rows = [
    {'address': '5412 N CLARK', 'date': '07/01/2012'},
    {'address': '5148 N CLARK', 'date': '07/04/2012'},
    {'address': '5800 E 58TH', 'date': '07/02/2012'},
    {'address': '2122 N CLARK', 'date': '07/03/2012'},
    {'address': '5645 N RAVENSWOOD', 'date': '07/02/2012'},
    {'address': '1060 W ADDISON', 'date': '07/02/2012'},
    {'address': '4801 N BROADWAY', 'date': '07/01/2012'},
    {'address': '1039 W GRANVILLE', 'date': '07/04/2012'},
]

for date, items in groupby(rows, key=itemgetter('date')):
    print(date)
    for i in items:
        print('     %s' % i)

07/01/2012
     {'address': '5412 N CLARK', 'date': '07/01/2012'}
07/04/2012
     {'address': '5148 N CLARK', 'date': '07/04/2012'}
07/02/2012
     {'address': '5800 E 58TH', 'date': '07/02/2012'}
07/03/2012
     {'address': '2122 N CLARK', 'date': '07/03/2012'}
07/02/2012
     {'address': '5645 N RAVENSWOOD', 'date': '07/02/2012'}
     {'address': '1060 W ADDISON', 'date': '07/02/2012'}
07/01/2012
     {'address': '4801 N BROADWAY', 'date': '07/01/2012'}
07/04/2012
     {'address': '1039 W GRANVILLE', 'date': '07/04/2012'}