def get_graph_label(self,
                        graph,
                        label="f(x)",
                        x=None,
                        direction=RIGHT,
                        buff=MED_SMALL_BUFF,
                        color=None):
        if isinstance(label, str):
            label = Tex(label)
        if color is None:
            label.match_color(graph)
        if x is None:
            # Searching from the right, find a point
            # whose y value is in bounds
            max_y = FRAME_Y_RADIUS - label.get_height()
            max_x = FRAME_X_RADIUS - label.get_width()
            for x0 in np.arange(*self.x_range)[::-1]:
                pt = self.i2gp(x0, graph)
                if abs(pt[0]) < max_x and abs(pt[1]) < max_y:
                    x = x0
                    break
            if x is None:
                x = self.x_range[1]

        point = self.input_to_graph_point(x, graph)
        angle = self.angle_of_tangent(x, graph)
        normal = rotate_vector(RIGHT, angle + 90 * DEGREES)
        if normal[1] < 0:
            normal *= -1
        label.next_to(point, normal, buff=buff)
        label.shift_onto_screen()
        return label
 def generate_n_choose_k_mobs(self):
     self.coords_to_n_choose_k = {}
     for n, k in self.coords:
         nck_mob = Tex(r"{%d \choose %d}" % (n, k))
         scale_factor = min(
             1,
             self.portion_to_fill * self.cell_height / nck_mob.get_height(),
             self.portion_to_fill * self.cell_width / nck_mob.get_width(),
         )
         center = self.coords_to_mobs[n][k].get_center()
         nck_mob.center().scale(scale_factor).shift(center)
         if n not in self.coords_to_n_choose_k:
             self.coords_to_n_choose_k[n] = {}
         self.coords_to_n_choose_k[n][k] = nck_mob
     return self