Python创建多层动态字典

Question

I want to create a 3 layer dictionary. All keys and values are strings and only their presence in the dictionary is important (I want to remove repetition and order is not important). So this is the function I wrote:

def UpdateDic3(key1,key2,key3,val,dic):
  if not key1 in dic.keys():
    dic[key1][key2][key3] = {val}
  elif not key2 in dic[key1].keys():
      dic[key1][key2][key3] = {val}
  elif not key3 in dic[key1][key2].keys():
      dic[key1][key2][key3] = {val}
  else:
      dic[key1][key2][key3].add(val)
  return dic

and searching for multilayer dictionary I found this:

l=lambda:defaultdict(l)
src_tree =l()

src_tree = UpdateDic3(k1,k2,k3,value,src_tree)

Isn't there a better way to make a 3 layer dictionary than the l=lambda:defaultdict(l) ?

I need a tree structure, with access to every layer's keys.

Answer 1

Just use a set filled with tuples.

src_tree = set()
str_tree.add((k1, k2, k3))

Answer 2

def multiple_dictionary(k, v): 
    if len(k) > 1: 
        v = multiple_dictionary(k[1:], v) 
    return {k[0]: v}