Streaming heatmap example with IPyLeaflet

streaming_heatmap_example.ipynb

{
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  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Streaming heatmap example\n",
    "\n",
    "This is an experiment adding a streaming effect to the heatmap example bundled in the [IPyLeaflet](https://github.com/jupyter-widgets/ipyleaflet) package. At the moment the streaming effect is achieved by swapping layers in a map, replacing a layer with outdated data by a newer one. Ideally, there should be one Layer, able to update itself."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [],
   "source": [
    "import time\n",
    "from random import uniform\n",
    "\n",
    "from ipyleaflet import Map, Heatmap"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Static Heatmap"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [],
   "source": [
    "def create_random_data(length):\n",
    "    \"Return a list of some random lat/lon/value triples.\"\n",
    "    return [[uniform(-80, 80), \n",
    "             uniform(-180, 180), \n",
    "             uniform(0, 1000)] for i in range(length)]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "application/vnd.jupyter.widget-view+json": {
       "model_id": "8db798201c734343965d0c75a6ecdabc",
       "version_major": 2,
       "version_minor": 0
      },
      "text/plain": [
       "Map(basemap={'url': 'https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png', 'max_zoom': 19, 'attribution': 'Map …"
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    }
   ],
   "source": [
    "data = create_random_data(1000)\n",
    "m = Map(center=(0, 0), zoom=2)\n",
    "heatmap = Heatmap(locations=data, radius=20)\n",
    "m.add_layer(heatmap);\n",
    "m"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Update data once"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [],
   "source": [
    "data2 = create_random_data(1000)\n",
    "heatmap2 = Heatmap(locations=data2, radius=20)\n",
    "m -= heatmap\n",
    "m += heatmap2\n",
    "heatmap = heatmap2"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Changes are reflected in the map above."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Update data continuously\n",
    "\n",
    "For this example we do this in a for-loop, but the idea is to do this via some streaming/messaging mechanism."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [],
   "source": [
    "for i in range(100):\n",
    "    data2 = create_random_data(1000)\n",
    "    heatmap2 = Heatmap(locations=data2, radius=20)\n",
    "    m -= heatmap\n",
    "    m += heatmap2\n",
    "    heatmap = heatmap2\n",
    "    time.sleep(0.1)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Again, changes over some period of time are reflected in the map above."
   ]
  }
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N.B.: GitHub doesn't render the included output map, but you will see it when running this code locally. But it looks not much different from the one here: https://ipyleaflet.readthedocs.io/en/latest/api_reference/heatmap.html