Python: convert defaultdict to dict

How can i convert a defaultdict

    number_to_letter
    defaultdict(<class 'list'>, {'2': ['a'], '3': ['b'], '1': ['b', 'a']})

to be a common dict?

    {'2': ['a'], '3': ['b'], '1': ['b', 'a']}

You can simply call dict:

    >>> a
    defaultdict(<type 'list'>, {'1': ['b', 'a'], '3': ['b'], '2': ['a']})
    >>> dict(a)
    {'1': ['b', 'a'], '3': ['b'], '2': ['a']}

but remember that a defaultdict is a dict:

    >>> isinstance(a, dict)
    True

just with slightly different behaviour, in that when you try access a key which is missing -- which would ordinarily raise a KeyError -- the default_factory is called instead:

    >>> a.default_factory
    <type 'list'>

That's what you see when you print a before the data side of the dictionary appears.

So another trick to get more dictlike behaviour back without actually making a new object is to reset default_factory:

    >>> a.default_factory = None
    >>> a[4].append(10)
    Traceback (most recent call last):
      File "<ipython-input-6-0721ca19bee1>", line 1, in <module>
        a[4].append(10)
    KeyError: 4

but most of the time this isn't worth the trouble.

From: stackoverflow.com/q/20428636

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