将字典列表拆分为大块

Question

I have a python list with two list inside(one for each room - there are 2 rooms), with dictionaries inside.

How can i transform this:

A = [
        [{'rate': Decimal('669.42000'), 'room': 2L, 'name': u'10% OFF'}, 
         {'rate': Decimal('669.42000'), 'room': 2L, 'name': u'10% OFF'}, 
         {'rate': Decimal('632.23000'), 'room': 2L, 'name': u'15% OFF'}, 
         {'rate': Decimal('632.23000'), 'room': 2L, 'name': u'15% OFF'}], 
        [{'rate': Decimal('855.36900'), 'room': 3L, 'name': u'10% OFF'}, 
         {'rate': Decimal('855.36900'), 'room': 3L, 'name': u'10% OFF'}]
]

Into This:

A = [
        [{'rate': Decimal('669.42000'), 'room': 2L, 'name': u'10% OFF'}, 
         {'rate': Decimal('669.42000'), 'room': 2L, 'name': u'10% OFF'}],
        [{'rate': Decimal('632.23000'), 'room': 2L, 'name': u'15% OFF'}, 
         {'rate': Decimal('632.23000'), 'room': 2L, 'name': u'15% OFF'}], 
        [{'rate': Decimal('855.36900'), 'room': 3L, 'name': u'10% OFF'}, 
         {'rate': Decimal('855.36900'), 'room': 3L, 'name': u'10% OFF'}]
]

I need to create in the main list, three lists inside. one for each type of promo. Thanks

Answer 1

Using itertools.groupby , you could use this nested comprehension:

>>> from itertools import groupby
>>> from pprint import pprint

>>> x = [list(g) for l in A for k, g in groupby(sorted(l))]
>>> pprint(x)
[[{'name': u'10% OFF', 'rate': Decimal('669.42000'), 'room': 2L},
  {'name': u'10% OFF', 'rate': Decimal('669.42000'), 'room': 2L}],
 [{'name': u'15% OFF', 'rate': Decimal('632.23000'), 'room': 2L},
  {'name': u'15% OFF', 'rate': Decimal('632.23000'), 'room': 2L}],
 [{'name': u'10% OFF', 'rate': Decimal('855.36900'), 'room': 3L},
  {'name': u'10% OFF', 'rate': Decimal('855.36900'), 'room': 3L}]]

You can provide a key function to both sorted and groupby (preferably the same) in order to group by a specific property:

from operator import itemgetter
fnc = itemgetter('rate')  # if you want to group by rate
x = [list(g) for l in A for k, g in groupby(sorted(l, key=fnc), key=fnc)]