无法从剧情中删除axvspan

Question

我试图在第三次点击图表后删除axvspan（）函数。

到目前为止，这是我的代码：

def shaded_region(self, event):     
    if event.button == 1 and ViewWidget.click == 0:
        ViewWidget.click +=1
        ViewWidget.xx1 = event.xdata
        self.cid2 = self.figure_canvas.mpl_connect("motion_notify_event", self.mouseCoordsInMotion)

def mouseCoordsInMotion(self, event):
    X1 = ViewWidget.xx1
    X2 = event.xdata

    self.aspan = self.axes.axvspan(X1,X2, alpha = 0.3, color = "cyan")
    self.figure_canvas.draw_idle()

    self.cid3 = self.figure_canvas.mpl_connect('button_press_event', self.selectedRegion)

def selectedRegion(self, event):

    ViewWidget.click += 1

    if event.button == 1 and ViewWidget.click == 2:
        print "Conectado a selectedRegion"
        self.figure_canvas.mpl_disconnect(self.cid1)
        self.figure_canvas.mpl_disconnect(self.cid2)

        ViewWidget.click = 3
        X1 = ViewWidget.xx1
        ViewWidget.xx2 = event.xdata
        X2 = ViewWidget.xx2

        self.aspan = self.axes.axvspan(X1,X2, alpha = 0.3, color = "cyan")
        return ViewWidget.xx1, ViewWidget.xx2, ViewWidget.click

    else:
        ViewWidget.click = 3
        self.figure_canvas.mpl_disconnect(self.cid3)

def erase_selection(self, event):

    if event.button == 1 and ViewWidget.click == 3:
        ViewWidget.click = 0
        self.aspan.remove()
        self.figure_canvas.draw_idle()

所以，使用方法shaded_region当我点击一次时，我开​​始从鼠标的坐标绘图。然后我再次点击停止绘图，当我想删除我用第三次点击绘制的内容时，它不起作用。

我怎样才能做到这一点？希望你能帮帮我。