将值从一个字典添加到另一个字典

Question

dict_1 = {1: {2}, 2: {3}, 3: {4}, 4: {11}}

dict_2 = {1: {2}, 2: {1}, 3: {4}, 4: {1,3}}

获得：

dict_1 = {1: {2}, 2: {3,1}, 3: {4}, 4: {11,1,3}}

如何将 dict_2 中的值添加到 dict_1 中而不删除已有的值？我可以将它们添加为列表，但由于某种原因，在尝试添加它们时，我得到了不可散列的错误列表：

to_add = set()
 for x in dict_2:
  if x in dict_1.keys():
  to_add.add(dict_1[x])
  to_add.add(dict_2[x])
  dict_1[x] = to_add

Answer 1

dict_1 = {1: {2}, 2: {3}, 3: {4}, 4: {11}}
dict_2 = {1: {2}, 2: {1}, 3: {4}, 4: {1, 3}}

for key, value in dict_2.items():
    if key in dict_1:
        dict_1[key].update(value)
    else:
        dict_1[key] = value

这应该有效