Multijection.py

# Generalization of dict, representing a multijection of m key sets K = k1,...,kn ; J = j1,...,jn ; ... ; Z = z1,...,zn
# storage complexity is O(m*n)
# set_view_index chooses the current key set to be used, all the remaining key sets are treated as value sets (the "total" value is returned as list)
# semantically equivalent to a SQL database table, in which every single column can be considered as a primary key one
# Assumption: every single column must not contain duplicate values within itself
# (BUT, an item can appear in different columns, even in the same position)

class Multijection(dict):
    # each one of args is a list of items, each one that can be used as key
    def __init__(self, *args):
        super().__init__()
        assert len(set(len(arg) for arg in args)) == 1 # each list must have the same size
        self.lists = args
        self.d = {} # backing dict for current view
        self.set_view_index(0)

    def set_view_index(self, idx):
        if idx >= len(self.lists):
            raise IndexError('Out of bounds')
        keys = self.lists[idx]
        values = []
        for i in range(len(self.lists[0])):
            values.append([x[i] for j,x in enumerate(self.lists) if j != idx])
        self.d = dict(zip(keys,values))

    def items(self):
        return self.d.items()

    def clear(self):
        raise NotImplementedError

    def popitem(self):
        raise NotImplementedError

    def keys(self):
        return self.d.keys()

    def values(self):
        return self.d.values()

    def get(self, key):
        return self.d.get(key)

    def __iter__(self):
        return self.d.__iter__()

    def __str__(self):
        return self.d.__str__()

    def __contains__(self, o):
        return self.d.__contains__(o)

    def contains_any(self, o):
        return any(x.__contains__(o) for x in self.lists)

    def __len__(self):
        return self.d.__len__()

    def __delitem__(self, v):
        raise NotImplementedError

    def __getitem__(self, k):
        return self.d.__getitem__(k)




if __name__ == '__main__':
    d = Multijection(['a', 'b', 'c'], [3.0, 2, 1.16], ['name1', 'name2', 'name3'])
    # d.set_view_index(0) # already called during __init__
    print(d['a']) # [3.0, 'name1']
    d.set_view_index(1)
    print(d[1.16])  # ['c', 'name3']