class Value:
    """
    Dense object that holds parameters.
    """

    def __init__(self, n):
        self._params = np.ones(n)
        self._n = n

    def dot(self, update):
        score = 0
        for position, value in zip(update._positions, update._values):
            score += self._params[int(position % self._n)] * value
        return score

    def assign(self, other):
        """
        self = other
        other is Value.
        """
        self = np.copy(other)

    def assign_mul(self, coeff):
        """
        self = self * coeff
        coeff is float.
        """
        self._params = np.multiply(self._params, coeff)

    def assign_madd(self, x, coeff):
        """
        self = self + x * coeff
        x can be either Value or Update.
        coeff is float.
        """
        if isinstance(x, Value):
            self._params = np.add(self._params, np.multiply(x._params, coeff))

        if isinstance(x, Update):
            for position, value in zip(x._positions, x._values):
                self._params[int(position % self._n)] += value * coeff