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    "import json\n",
    "import copy\n",
    "from ipyleaflet import (\n",
    "    Map,\n",
    "    GeoJSON,\n",
    "    Layer\n",
    ")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
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   "source": [
    "m = Map(center=[53.88, 27.45], zoom=3, name='Base map')\n",
    "m"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
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   "source": [
    "# geojson layer with hover handler\n",
    "with open('./europe_110.geo.json') as f:\n",
    "    data = json.load(f)\n",
    "\n",
    "for feature in data['features']:\n",
    "    feature['properties']['style'] = {\n",
    "        'color': 'grey',\n",
    "        'weight': 1,\n",
    "        'fillColor': 'grey',\n",
    "        'fillOpacity': 0.2\n",
    "    }\n",
    "\n",
    "selected_set = set()\n",
    "selected_layer = None\n",
    "\n",
    "def convert_selected_set_to_geojson(selected_set):\n",
    "    geojson = {'type': 'FeatureCollection', 'features': []}\n",
    "    geojson['features'] = [feature for feature in data['features'] if feature['properties']['iso_a3'] in selected_set]\n",
    "    for feature in data['features']:\n",
    "        feature['properties']['style'] = {'color': 'yellow', 'weight': 2,'fillColor': 'grey', 'fillOpacity': 0.2} \n",
    "    return geojson\n",
    "\n",
    "def selected_onclick_handler(event=None, id=None, properties=None, **args):\n",
    "    global selected_layer\n",
    "    if properties is None:\n",
    "        return\n",
    "    cid = properties['iso_a3']\n",
    "    selected_set.remove(cid)\n",
    "    if selected_layer is not None:\n",
    "        m.remove_layer(selected_layer)\n",
    "    selected_layer = GeoJSON(data=convert_selected_set_to_geojson(selected_set),\n",
    "                             name='Selected EU Countries',\n",
    "                             hover_style={'fillColor': 'yellow'}\n",
    "                            )\n",
    "    selected_layer.on_click(selected_onclick_handler)\n",
    "    m.add_layer(selected_layer)\n",
    "\n",
    "def geojson_onclick_handler(event=None, id=None, properties=None, **args):\n",
    "    global selected_layer\n",
    "    if properties is None:\n",
    "        return\n",
    "    cid = properties['iso_a3']\n",
    "    selected_set.add(cid)\n",
    "    if selected_layer is not None:\n",
    "        m.remove_layer(selected_layer)\n",
    "    selected_layer = GeoJSON(data=convert_selected_set_to_geojson(selected_set),\n",
    "                             name='Selected EU Countries',\n",
    "                             hover_style={'fillColor': 'yellow'}\n",
    "                            )\n",
    "    selected_layer.on_click(selected_onclick_handler)\n",
    "    m.add_layer(selected_layer)\n",
    "    \n",
    "    \n",
    "geojson_layer = GeoJSON(data = data, name='EU Countries', hover_style={'fillColor': 'red'})\n",
    "geojson_layer.on_click(geojson_onclick_handler)\n",
    "m.add_layer(geojson_layer)"
   ]
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