Returns the EdgePaths by generating a triangle for each simplex.

def edgepaths(self):
        """
        Returns the EdgePaths by generating a triangle for each simplex.
        """
        if self._edgepaths:
            return self._edgepaths
        elif not len(self):
            edgepaths = self.edge_type([], kdims=self.nodes.kdims[:2])
            self._edgepaths = edgepaths
            return edgepaths

        simplices = self.array([0, 1, 2]).astype(np.int32)
        pts = self.nodes.array([0, 1]).astype(float)
        pts = pts[simplices]
        paths = np.pad(pts[:, [0, 1, 2, 0], :],
                       pad_width=((0, 0), (0, 1), (0, 0)),
                       mode='constant',
                       constant_values=np.nan).reshape(-1, 2)[:-1]
        edgepaths = self.edge_type([paths],
                                    kdims=self.nodes.kdims[:2])
        self._edgepaths = edgepaths
        return edgepaths