python中将字典相同key处理不同的value，将value相加给相同的key

good_id =  [{'goods_id': 9, 'buy_num': 1.0}, {'goods_id': 8, 'buy_num': 8.0}, {'goods_id': 7, 'buy_num': 4.0}, {'goods_id': 9, 'buy_num': 1.0}, {'goods_id': 3, 'buy_num': 1.0}, {'goods_id': 2, 'buy_num': 1.0}, {'goods_id': 6, 'buy_num': 1.0}]
# reverse=False 默认升序，reverse=True降序
good_id.sort(key=lambda x: x["goods_id"],reverse=True)#对goods_id排序
print("good_id==",good_id)
from operator import itemgetter
from itertools import groupby
for id,va in groupby(good_id,key=itemgetter("goods_id")):
    data = {}
    sm = []
    key = None
    for i in va:
        key=i["goods_id"]#对goods_id相同的字段
        x = i["buy_num"]#对buy_num进行相加
        sm.append(x)

    data["goods_id"]=key
    data["buy_num"]=sum(sm)
    print("data===",data)

打印语句如下：

good_id== [{'goods_id': 9, 'buy_num': 1.0}, {'goods_id': 9, 'buy_num': 1.0}, {'goods_id': 8, 'buy_num': 8.0}, {'goods_id': 7, 'buy_num': 4.0}, {'goods_id': 6, 'buy_num': 1.0}, {'goods_id': 3, 'buy_num': 1.0}, {'goods_id': 2, 'buy_num': 1.0}]
data=== {'goods_id': 9, 'buy_num': 2.0}
data=== {'goods_id': 8, 'buy_num': 8.0}
data=== {'goods_id': 7, 'buy_num': 4.0}
data=== {'goods_id': 6, 'buy_num': 1.0}
data=== {'goods_id': 3, 'buy_num': 1.0}
data=== {'goods_id': 2, 'buy_num': 1.0}