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• 14.根据字段将记录分组

20.1.14. 14.根据字段将记录分组

#!/usr/bin/env python
# -*- coding:utf8 -*-
# auther; 18793
# Date：2020/4/1 16:17
# filename: 14.根据字段将记录分组.py

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'},

]

# 现在假设想根据日期以分组的方式迭代数据。要做到这些，首先以目标字段（在这个例子中是date）来对序列排序，然后再使用itertools.groupby()。
from operator import itemgetter
from itertools import groupby

# Sort by the desired field first
rows.sort(key=itemgetter('date'))
# Iterate in groups

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


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