python dict 合并

Question

现有 a , b 两个字典，他们都有一个共同的id 1 ， 实现dict的合并
和mysql中 select a.id,a.MUT,b.neighbor from a full join b on a.id = b.id
执行结果很类似

    a =  {
        "id": "1",
        "MUT": "1500",
    }
    b =  {
        "id": "1",
        "neighbor": [2]
    }
    # result = addfunction(a,b)
    result = {
        "id": "1",
        "MUT": "1500",
        "neighbor": [2]
    }

如何实现？

---

---

考虑复杂情况：

a =  [
    {
        "id": "1",
        "MUT": "1500",
    },
    {
        "id": "2",
        "MUT": "1500",
    }
]
b =  [
    {
        "id": "1",
        "neighbor": [2]
    },
     {
        "id": "3",
        "neighbor": [2]
    }
]
# result = addfunction(a,b)
result = [
    {
        "id": "1",
        "MUT": "1500",
        "neighbor": [2]
    },
     {
        "id": "2",
        "MUT": "1500",
    },
     {
        "id": "3",
        "neighbor": [2]
    }
]

Answer 1

l_a = len(a)
l_b = len(b)

b_map = {}
result = []
for _ in range(l_b):
    i = b.pop()
    b_map[i['id']] = i

for _ in range(l_a):
    i = a.pop()
    if i['id'] in b_map:
        i.update(b_map.pop(i['id']))
    result.append(i)

result.extend(b_map.values())
print(result)

[{'MUT': '1500', 'id': '2'}, {'MUT': '1500', 'id': '1', 'neighbor': [2]}, {'id': '3', 'neighbor': [2]}]

Answer 2

from collections import defaultdict

def combineListDict(l1,l2,joinKeys = ["id"]):
    d = defaultdict(dict)
    for l in (l1, l2):
        for elem in l:
            if len(joinKeys) == 1:
                joinKeysStr = elem[joinKeys[0]]
            else:
                joinKeysStr = reduce((lambda x, y: str(elem[x]) + str(elem[y])),joinKeys)
            d[joinKeysStr].update(elem)
    return d.values()

因为join on 条件可能时多个值，我在stack上找了个代码改了一下。