如果字典项是相同的，如何求和字典项的数量

Question

Shopping_list= [
{"title":"cheese","quantity":50,"unit":"gm"},
{"title":"cheese","quantity":40,"unit":"gm"},
{"title":"curd","quantity":20,"unit":"gm"}
]

我只想在标题匹配时对数量进行求和，然后想要下面的输出列表：

final_list = [
     {"title":"cheese","quantity":90,"unit":"gm"},
     {"title":"curd","quantity":20,"unit":"gm"}]

Answer 1

您可以使用排序按“标题”和“单位”。然后根据这个排序列表分组，并计算每个组的和。

from itertools import groupby

def key_func(k):
    return k['title'],k['unit']

Shopping_list = sorted(Shopping_list, key=key_func)
result = []
for key,value in groupby(Shopping_list, key_func):
    total = 0
    for item in list(value):
        total+= item['quantity']
    result.append({'title': key[0],'quantity':total, 'unit': key[1]})

print(result)

Answer 2

shopping_list= [
    {"title":"cheese","quantity":50,"unit":"gm"},
    {"title":"cheese","quantity":40,"unit":"gm"},
    {"title":"curd","quantity":20,"unit":"gm"}
]

agg = {}

for entry in shopping_list:
    if entry["title"] not in agg:
        agg[entry["title"]] = entry
    else:
        agg[entry["title"]]["quantity"] += entry["quantity"]

final_list = list(agg.values())

Answer 3

您所需要做的就是遍历Shopping_list并检查result列表中的dicts的title (通过简单的线性搜索)。如果有带有该标题的字典，则增加quantity的数量，否则该标题是新的，然后将字典转移到result列表。

Shopping_list = [
    {"title": "cheese", "quantity": 50, "unit": "gm"},
    {"title": "cheese", "quantity": 40, "unit": "gm"},
    {"title": "curd", "quantity": 20, "unit": "gm"},
]

result = []
for d1 in Shopping_list:
    for d2 in result:
        if d2["title"] == d1["title"]:
            d2["quantity"] += d1["quantity"]
            break
    else:
        result.append(d1)

print(result)