如何在Python词典中合并数据

Question

I have a python dictionary like

my_list = [{'orderproduct_id': 76, 'orderproduct_quantity': '500', 'orderbatch_id': 'FOX19022019-2'}, 
           {'orderproduct_id': 76, 'orderproduct_quantity': '500', 'orderbatch_id': 'FOX19022019-1'}, 
           {'orderproduct_id': 77, 'orderproduct_quantity': '100', 'orderbatch_id': 'FOX19022019-1'}]

I want output like

my_list = [{'orderproduct_id': 76, 
            'batches': [{'orderproduct_quantity': '500', 'orderbatch_id': 'FOX19022019-2'}, 
                        {'orderproduct_quantity': '500', 'orderbatch_id': 'FOX19022019-1'}
                       ]
           }, 
           {'orderproduct_id': 77, 
            'batches': [{'orderproduct_quantity': '100', 'orderbatch_id': 'FOX19022019-1'}
                       ]
           }]

I am using that in Django view so if any Django function or python concept can work please let me know. Thanks.

Answer 1

Try something like the following! First of all, create a dictionary to keep as key the orderproduct_id , appending every orderproduct_quantity and orderbatch_id (both as a dictionary to a list). Then, just convert the dictionary to a list of dictionaries using a compression list, where the key will be the orderproduct_id and the value , the batches .

output = {}
for p in my_list:
    id = p['orderproduct_id'] 
    if id not in output: # Create empty list for new IDs
        output[id] = []
    d = { 'orderproduct_quantity': p['orderproduct_quantity'],
          'orderbatch_id': p['orderbatch_id'] }
    output[id].append(d)

output = [{ 'orderproduct_id': k, 'batches': v } for k, v in output.items()]

Answer 2

You can use itertools:

from itertools import groupby

new_list = [ {'orderproduct_id': k, 'batches': list(i)}  
              for k, i in groupby(my_list, lambda x: x['orderproduct_id'])  ]

Edited

Edited to:

1. Sort list to use groupby safely.
2. Exclude key on inner list.

New code:

from itertools import groupby

my_key = lambda x: x['orderproduct_id']

[ {'orderproduct_id': k, 
   'batches': [ d for d in i if d.pop('orderproduct_id')  ]}  
  for k, i in groupby( sorted(my_list,key=my_key), my_key )  ]

Explanation

You are grouping by orderproduct_id . Then, the natural way is to use groupby function. When another developer see groupby in few seconds he/she understand that the code is grouping elements.

Also, my approach uses list comprehension because you are creating new list/dictionaries from another iterables.

Answer 3

You can aggregate your items by orderproduct_id is separated dict:

aggregator = defaultdict(list)
for item in my_list:
    aggregator[item.pop('orderproduct_id')].append(item)

Then make a new list out of aggregated dict items:

new_list = []
for key, value in aggregator.items():
    new_list.append({
        'orderproduct_id': key,
        'batches': value
    })