def robotsrulesetOfDomain(self, domain):
		'''检查domain是否在数据库中,
			否 --> (False, None)
			是 --> (True, 数据库中存储的robots.txt内容)
		'''
		exist = False
		cur = self.conn.cursor()
		# 是否存在
		cur.execute("SELECT 1 FROM Domains WHERE domain=?", (domain,))
		if cur.fetchone() :
			exist = True
		# 存在的话,结果是什么
		cur.execute("SELECT rules FROM Domains,Rulesets "
			"WHERE domain=? AND Domains.did=Rulesets.did"
			,(domain,) )
		ruleset = cur.fetchone()
		return (exist, ruleset)
def forcedens_fft(title, fdens, ax=0):
    """plot force densities FFT
    Args:
      title: plot title
      fdens: force density object
    """
    if ax == 0:
        ax = plt.axes(projection="3d")

    F = 1e-3*fdens.fft()
    fmin = 0.2
    num_bars = F.shape[0] + 1
    _xx, _yy = np.meshgrid(np.arange(1, num_bars),
                           np.arange(1, num_bars))
    z_size = F[F > fmin]
    x_pos, y_pos = _xx[F > fmin], _yy[F > fmin]
    z_pos = np.zeros_like(z_size)
    x_size = 2
    y_size = 2

    ax.bar3d(x_pos, y_pos, z_pos, x_size, y_size, z_size)
    ax.view_init(azim=120)
    ax.set_xlim(0, num_bars+1)
    ax.set_ylim(0, num_bars+1)
    ax.set_title(title)
    ax.set_xlabel('M')
    ax.set_ylabel('N')
    ax.set_zlabel('kN/m²')