combinations.py

class InvalidInput(Exception):
    pass


def possible_combinations(attributes):
    """Takes in a user_attribute like described above, and returns
    all possible combinations of 1 of each of the attributes
    Every attribute has a list

    Returns:
    =======
    prints out all the uniques, one by line
    """
    keys = attributes.keys()
    results = []
    for key in keys:
        if not isinstance(attributes[key], list):
            raise InvalidInput

    def recursive_down(current_values, attributes, results):
        """
        current_keys: list of previously selected keys to keep until we reach the bottom
        attributes: what is left of the attributes dict (gets smaller every iteration)
        results: the global results we're saving
        """
        if len(attributes.keys()) == 0:
            results.append(current_values)
            return

        new_key = attributes.keys()[0]
        temp_attributes = attributes.copy()
        del temp_attributes[new_key]
        for elt in attributes[new_key]:
            recursive_down(current_values + [elt], temp_attributes, results)

        return

    recursive_down([], attributes, results)
    return results


user_attribute = {
    'Country': ['US', 'CA', 'CH', 'JP'],
    'AgeRange': ['0-20', '21-30', '31-40'],
    'Gender': ['M', 'F'],
    'Income': ['L', 'M', 'H'],
    'MusicPref': ['Jazz', 'Pop'],
}

combinations = possible_combinations(user_attribute)
for combination in combinations:
    print combination