get a specific subdic in a nested dic based on key

Question

I have a nested dictionary. And I would like to extract a sub dictionary based on a certain attribute: Here is a simpler version of my dictionary:

subdata = {
     "id": 997,
     "acronym": "root",
     "color_hex_triplet": "FFFFFF",
     "children": [
      {
       "id": 8,
       "acronym": "grey",
       "color_hex_triplet": "BFDAE3",
       "children": [
        {
         "id": 567,
         "acronym": "CH",
         "color_hex_triplet": "B0F0FF",
         "children": [
          {
           "id": 688,
           "acronym": "CTX",
           "color_hex_triplet": "B0FFB8",
           "children": [
            {
             "id": 695,
             "acronym": "CTXpl",
             "color_hex_triplet": "70FF70",
             "children": [
              {
               "id": 315,
               "acronym": "Isocortex",
               "color_hex_triplet": "70FF71",
               "children": [
                {
                 "id": 184,
                 "acronym": "FRP",
                 "color_hex_triplet": "268F45",
                 "children": [
                  {
                   "id": 68,
                   "acronym": "FRP1",
                   "color_hex_triplet": "268F45",
                   "children": []
                  },
                                    {
                   "id": 69,
                   "acronym": "FRP2",
                   "color_hex_triplet": "268F45",
                   "children": []
                  }]}]}]}]}]]}]}]}

And based on e.g. "acronym": "FRP" I want to get that certain dictionary and all its children like this:

region_dict = {
"id": 184,
"acronym": "FRP",
"color_hex_triplet": "268F45",
"children": [
{
"id": 68,
"acronym": "FRP1",
"color_hex_triplet": "268F45",
"children": []},
{"id": 69,
"acronym": "FRP2",
"color_hex_triplet": "268F45",
"children": []
}]}

I tried the following code (from Aplet123's suggestion), but it does not seem to return the dictionary. It only returns True. Am I doing something wrong?

def get_parent_dict(dic, reg):
    if dic['acronym'] == reg:
        return dic
    for child in dic["children"]:
        result = get_parent_dict(child, reg) is not None
        if result is not None:
            return result
    return None # not technically needed

f = open(json_path) 
data = json.load(f) 

subdata = data['msg'][0] #this is a nested dictionary

region_dict = get_parent_dict(subdata, "FRP")

Does this answer your question? [How can I search for specific keys in this nested dictionary in Python?](https://stackoverflow.com/questions/49662970/how-can-i-search-for-specific-keys-in-this-nested-dictionary-in-python) — Ethicist, Dec 18 '20 at 22:23
Not really. Because in that case it is looking to find a certain key. In my case the key "id" is present in all childs. But I need to find the one with a specific value. and the return the dictionary that includes that id and all it's childs as a nested dictionary — Maryam Sadeghi, Dec 18 '20 at 22:43

Aplet123 · Accepted Answer · 2020-12-19T02:03:14.240

1

You can use a depth first search:

def dfs_for_id(dic, id):
    if dic["id"] == id:
        return dic
    for child in dic["children"]:
        result = dfs_for_id(child, id)
        if result is not None:
            return result
    return None # not technically needed

edited Dec 19 '20 at 02:03

answered Dec 18 '20 at 22:24

Aplet123

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The problem with this is that it only goes through one level of children, whereas it might be in the 3rd level of children – Maryam Sadeghi Dec 18 '20 at 22:26
This goes through every level: it's recursive and will only stop until it reaches the end. – Aplet123 Dec 18 '20 at 22:27
Ok, yes you're right. I tested it. But this returns True, not the dictionary. Am I doing something wrong? – Maryam Sadeghi Dec 18 '20 at 22:41
@MaryamSadeghi I made a typo, it should work now. – Aplet123 Dec 19 '20 at 02:03
Sorry, what did you change? But I really think this should be the way. thank you. But still does not seem to work – Maryam Sadeghi Dec 19 '20 at 11:52

get a specific subdic in a nested dic based on key

1 Answers1