On: One-line Tree In Python

[krosaen]

related, but not as clever function to help with nested counters (with doctest showing usage):

    def incr_nestedctr(d, *keys, **kwargs):
        """
        >>> a = {}
        >>> incr_nestedctr(a, 'a', 'b', 'c', 'd')
        {'a': {'b': {'c': {'d': 1}}}}
        >>> incr_nestedctr(a, 'a', 'b', 'c', 'd')
        {'a': {'b': {'c': {'d': 2}}}}
        >>> incr_nestedctr(a, 'a', 'b', 'c', 'd', delta = -4)
        {'a': {'b': {'c': {'d': -2}}}}
        >>> incr_nestedctr({u'1.0': {u'0': 1, '5': 1}}, '1.0', '5', delta = 2)
        {u'1.0': {u'0': 1, '5': 3}}
        """
        delta = kwargs.get('delta', 1)
        thed = d
        for k in keys[:-1]:
            thed = thed.setdefault(k, {})
        thed.setdefault(keys[-1], 0)
        thed[keys[-1]] += delta
        return d