Python hash

[Paddy]

On Aug 18, 12:30 pm, Nick Craig-Wood <n... at craig-wood.com> wrote:
> I think that if you truly want to emulate a perl hash then you would
> want this which does the above but recursively.
>
> from collections import defaultdict
>
> class hash(defaultdict):
>     def __init__(self):
>         defaultdict.__init__(self, hash)
>
> D=hash()
>
> D[1][2][3][4]=5
> D[1][4][5]=6
>
> print D
>
> --
> Nick Craig-Wood <n... at craig-wood.com> --http://www.craig-wood.com/nick
Nick,
I thought I'd save your hash implementation away in my bag of tricks:


# File: autovivifying_dict.py
from collections import defaultdict
class hash(defaultdict):
    """ Used like a dict except sub-dicts automagically created as
needed
    Based on: http://groups.google.com/group/comp.lang.python/msg/f334fbdafe4afa37

    >>> D=hash()
    >>> D[1][2][3][4]=5
    >>> D[1][4][5]=6
    >>> D
    hash({1: hash({2: hash({3: hash({4: 5})}), 4: hash({5: 6})})})
    >>> hash({1: hash({2: hash({3: hash({4: 5})}), 4: hash({7: 8})})})
    hash({1: hash({2: hash({3: hash({4: 5})}), 4: hash({7: 8})})})
    >>>

    """
    def __init__(self, *a, **b):
        defaultdict.__init__(self, hash, *a, **b)
    def __repr__(self):
        return "hash(%s)" % (repr(dict(self)),)

def _test():
    import doctest
    doctest.testmod()

if __name__ == "__main__":
    _test()



- Paddy.