voila/callback_matplotlib_widget_2.ipynb

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   "source": [
    "# Matplotlib widget from callback\n",
    "\n",
    "With [ipympl](https://github.com/matplotlib/jupyter-matplotlib), the figure's canvas is a widget.  That means you can add it to a layout using boxes, which we do here to put the Run button above the plot.  However, calling `plt.figure()` would normally render the widget immediately, so you end up getting two copies.  To avoid that, toggle interactive mode with `ioff()` and `ion()`."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "import ipympl\n",
    "import matplotlib.pyplot as plt\n",
    "import ipywidgets"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "%matplotlib widget"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "def callback(w):\n",
    "    plt.ion()\n",
    "    plt.plot([2, 1], [1, 2])\n",
    "    \n",
    "plt.ioff()\n",
    "fig = plt.figure()\n",
    "button = ipywidgets.Button(description='Run')\n",
    "button.on_click(callback)\n",
    "ipywidgets.VBox(children=[button, fig.canvas])"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": []
  }
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