snake.py 文件源码

def __init__(self, nn, xs, ys, alpha, beta, gamma, width, bc):
        """xs: x-coordinates
           ys: y-coordinates"""

        # load the vertices
        self.vertices = []
        for v in zip(xs, ys):
            self.vertices.append(array(v))
        self.vertices = array(self.vertices)
        self.length = self.vertices.shape[0]
        # boundary condition
        assert bc == 'PBC' or bc == 'OBC'
        self._bc = bc
        # width of snake (determining the sensing region)
        self.widths = np.ones((self.length, 1)) * width
        # for neighbour calculations
        id_ = np.arange(self.length)
        self.less1 = np.roll(id_, +1)
        self.less2 = np.roll(id_, +2)
        self.more1 = np.roll(id_, -1)
        self.more2 = np.roll(id_, -2)
        # implicit time-evolution matrix as in Kass
        self._A = alpha * self._alpha_term() + beta * self._beta_term()
        self._gamma = gamma
        self._inv = np.linalg.inv(self._A + self._gamma * np.identity(self.length))
        # the NN for this snake
        self.nn = nn