Fastest way to convert dict keys and values ​​from `unicode` to` str`?

Question

I get a dict from one “layer” of code on which some calculations / modifications are performed before passing it to another “layer”. The original dict keys and string values ​​are unicode , but the layer to which they are passed takes only str .

This will often be triggered, so I would like to know what would be the fastest way to convert something like:

 { u'spam': u'eggs', u'foo': True, u'bar': { u'baz': 97 } } 

... at:

 { 'spam': 'eggs', 'foo': True, 'bar': { 'baz': 97 } } 

... taking into account that values ​​other than the "string" should remain as their original type.

Any thoughts?

Answer 1

 DATA = { u'spam': u'eggs', u'foo': frozenset([u'Gah!']), u'bar': { u'baz': 97 }, u'list': [u'list', (True, u'Maybe'), set([u'and', u'a', u'set', 1])]} def convert(data): if isinstance(data, basestring): return str(data) elif isinstance(data, collections.Mapping): return dict(map(convert, data.iteritems())) elif isinstance(data, collections.Iterable): return type(data)(map(convert, data)) else: return data print DATA print convert(DATA) # Prints: # {u'list': [u'list', (True, u'Maybe'), set([u'and', u'a', u'set', 1])], u'foo': frozenset([u'Gah!']), u'bar': {u'baz': 97}, u'spam': u'eggs'} # {'bar': {'baz': 97}, 'foo': frozenset(['Gah!']), 'list': ['list', (True, 'Maybe'), set(['and', 'a', 'set', 1])], 'spam': 'eggs'} 

Assumptions:

• You have imported the collections module and can use the abstract base classes that it provides.
• You can convert using the default encoding (use data.encode('utf-8') , not str(data) if you need an explicit encoding).

If you need to support other types of containers, we hope that it will be obvious how to follow the pattern and add cases to them.

Answer 2

I know I'm late for this one:

 def convert_keys_to_string(dictionary): """Recursively converts dictionary keys to strings.""" if not isinstance(dictionary, dict): return dictionary return dict((str(k), convert_keys_to_string(v)) for k, v in dictionary.items()) 

Answer 3

If you want to do this inline and don't need a recursive descent, this might work:

 DATA = { u'spam': u'eggs', u'foo': True, u'bar': { u'baz': 97 } } print DATA # "{ u'spam': u'eggs', u'foo': True, u'bar': { u'baz': 97 } }" STRING_DATA = dict([(str(k), v) for k, v in data.items()]) print STRING_DATA # "{ 'spam': 'eggs', 'foo': True, 'bar': { u'baz': 97 } }" 

Answer 4

 def to_str(key, value): if isinstance(key, unicode): key = str(key) if isinstance(value, unicode): value = str(value) return key, value 

pass the key and value to it and add recursion to your code to account for the internal dictionary.

Answer 5

for a non-nested dict (since the name does not mention this case, this may be interesting for other people)

 {str(k): str(v) for k, v in my_dict.items()} 

Answer 6

To make everything inline (non-recursive):

 {str(k):(str(v) if isinstance(v, unicode) else v) for k,v in my_dict.items()}