from functools import reduce

from pydantic import BaseModel

from dataclasses import dataclass

a = {

    "class1": [{"id": 1, "name": "马良"}, {"id": 2, "name": "李四"}],

    "class2": [{"id": 3, "name": "马青"}, {"id": 4, "name": "王杰"}],

    "class3": [{"id": 5, "name": "赵六"}, {"id": 6, "name": "孙七"}],

}

a1 = [

    {"id": 1, "class": "class1", "name": "马良"},

    {"id": 2, "class": "class1", "name": "李四"},

    {"id": 3, "class": "class2", "name": "马青"},

    {"id": 4, "class": "class2", "name": "王杰"},

    {"id": 5, "class": "class3", "name": "赵六"},

    {"id": 6, "class": "class3", "name": "孙七"},

]

b = [{**item, "class": key} for key, values in a.items() for item in values]

def myAdd(x, y):

    if x.get(y["class"]):

        x[y["class"]].append(y)

    else:

        x[y["class"]] = [y]

    return x

b1 = reduce(myAdd, a1, {})

print(b1)