Using dict keys in python as values in a different dict
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I would like to create a "translator" type of dict that would assign values that are keys in different dicts, which are nested, to keys in a dict that I created.  The problem I run into is that I can't create a value that represents a nested dict key without having to convert that to a string or some other data type, and when I try to use a string as an index to the nested dict, I get an index error.  Ideally, my dict would look something like this:

    new_dict{
        "new_key_1" : ['subdict1']['subdict2']['old_key_1'],
        "new_key_2" : ['subdict1']['subdict2']['old_key_2'],
        "new_key_3" : ['subdict1']['subdict3']['old_key_3']
        }

Then, for each nested dict, I could generate a new dict object with a simple for loop:
 
    for key, value in new_dict.items() :
        user_dict_1[key] = OldDict[value]

The nested dicts are very large and I only need a few fields from each, otherwise I could just use the .copy() function to work with the old dicts.

PS- Any help in rewriting this question to be more readable also appreciated.