python 将值相同的key分组的方法

rows = [
     {‘address‘: ‘5412 N CLARK ‘, ‘date ‘: ‘07/12/2012 ’ }， 
     {‘address‘: ‘5148 N CLARK ‘, ‘date ’: ‘07/04/2012 ’ }， 
     {‘address‘: ‘5800 E 58TH ’, ‘date ’: ‘07 /12/2012 ’ }，   
]

from operator import itemgetter
from itertools import groupby


rows.sort(key=itemgetter(‘date‘))

for date, items in groupby(rows, key=itemgetter(‘date‘)):
    print(date)
    for i in items:
        print(‘ ‘, i)

from collections import defaultdict


rows_by_date = defaultdict(list)
for row in rows:
    rows_by_date[row[‘date‘]].append(row)