Python recursively replace character in keys of nested dictionary?

Question

I'm trying to create a generic function that replaces dots in keys of a nested dictionary. I have a non-generic function that goes 3 levels deep, but there must be a way to do this generic. Any help is appreciated! My code so far:

output = {'key1': {'key2': 'value2', 'key3': {'key4 with a .': 'value4', 'key5 with a .': 'value5'}}}   def print_dict(d):     new = {}     for key,value in d.items():         new[key.replace(".", "-")] = {}         if isinstance(value, dict):             for key2, value2 in value.items():                 new[key][key2] = {}                 if isinstance(value2, dict):                     for key3, value3 in value2.items():                         new[key][key2][key3.replace(".", "-")] = value3                 else:                     new[key][key2.replace(".", "-")] = value2         else:             new[key] = value     return new  print print_dict(output) 

UPDATE: to answer my own question, I made a solution using json object_hooks:

import json  def remove_dots(obj):     for key in obj.keys():         new_key = key.replace(".","-")         if new_key != key:             obj[new_key] = obj[key]             del obj[key]     return obj  output = {'key1': {'key2': 'value2', 'key3': {'key4 with a .': 'value4', 'key5 with a .': 'value5'}}} new_json = json.loads(json.dumps(output), object_hook=remove_dots)   print new_json 

Answer 1

Yes, there exists better way:

def print_dict(d):     new = {}     for k, v in d.iteritems():         if isinstance(v, dict):             v = print_dict(v)         new[k.replace('.', '-')] = v     return new 

(Edit: It's recursion, more on Wikipedia.)

Answer 2

Actually all of the answers contain a mistake that may lead to wrong typing in the result.

I'd take the answer of @ngenain and improve it a bit below.

My solution will take care about the types derived from dict (OrderedDict, defaultdict, etc) and also about not only list, but set and tuple types.

I also do a simple type check in the beginning of the function for the most common types to reduce the comparisons count (may give a bit of speed in the large amounts of the data).

Works for Python 3. Replace obj.items() with obj.iteritems() for Py2.

def change_keys(obj, convert):     """     Recursively goes through the dictionary obj and replaces keys with the convert function.     """     if isinstance(obj, (str, int, float)):         return obj     if isinstance(obj, dict):         new = obj.__class__()         for k, v in obj.items():             new[convert(k)] = change_keys(v, convert)     elif isinstance(obj, (list, set, tuple)):         new = obj.__class__(change_keys(v, convert) for v in obj)     else:         return obj     return new 

If I understand the needs right, most of users want to convert the keys to use them with mongoDB that does not allow dots in key names.