Simplify the logics of attributes of Heatmap class and compute vmin, vmax and colormap from gradient data (values and colors).

Author: HaudinFlorence

examples/Heatmap_with_colormap.ipynb

@@ -0,0 +1,88 @@
+{
+ "cells": [
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "98958552-db61-4b15-9025-8483234118b3",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "# Set up for JupyterLite\n",
+    "try:\n",
+    "    import piplite\n",
+    "    await piplite.install('ipyleaflet')\n",
+    "except ImportError:\n",
+    "    pass"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "974bc9b2-4a25-455b-8c4d-ca565e21f146",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "import ipyleaflet\n",
+    "from random import uniform\n",
+    "import time\n",
+    "from branca.colormap import linear, LinearColormap"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "fa27e0da-7047-4f06-93e8-3fb230e554d4",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "def create_random_data(length):\n",
+    "    \"Return a list of some random lat/lon/value triples.\"\n",
+    "    return [\n",
+    "        [uniform(-80, 80), uniform(-180, 180), uniform(0, 1000)] for i in range(length)\n",
+    "    ]"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "cd1fc9dd-addf-4085-95ff-b8d4b983491f",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "m = ipyleaflet.Map(center=[0, 0], zoom=2)\n",
+    "heat = ipyleaflet.Heatmap(locations=create_random_data(1000), radius=20, blur=10, gradient={0.25 : 'orange', 0.85 : 'red'})\n",
+    "colormap_control = ipyleaflet.ColormapControl(\n",
+    "        caption='Intensity',\n",
+    "        colormap=heat.colormap,\n",
+    "        value_min=heat.vmin,\n",
+    "        value_max=heat.vmax,\n",
+    "        position='topright',\n",
+    "        transparent_bg=True,\n",
+    "    )\n",
+    "m.add(heat)\n",
+    "m.add(colormap_control)"
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 3 (ipykernel)",
+   "language": "python",
+   "name": "python3"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 3
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython3",
+   "version": "3.9.13"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 5
+}

ipyleaflet/leaflet.py

@@ -823,15 +823,21 @@ class Heatmap(RasterLayer):
     radius = Float(25.0).tag(sync=True, o=True)
     blur = Float(15.0).tag(sync=True, o=True)
     gradient = Dict({0.4: 'blue', 0.6: 'cyan', 0.7: 'lime', 0.8: 'yellow', 1.0: 'red'}).tag(sync=True, o=True)
-    colors = ['blue', 'cyan', 'lime', 'yellow', 'red']
-    values = [0.4, 0.6, 0.7, 0.8, 1.0]
-    dict = {}
-    for i in range(len(values)):
-        dict[values[i]] = colors[i]
-    vmin = values[0]
-    vmax = values[len(values) - 1]
-    gradient = Dict(dict).tag(sync=True, o=True)
-    colormap = LinearColormap(colors, vmin=vmin, vmax=vmax)
+
+    def __init__(self, **kwargs):
+        super(Heatmap, self).__init__(**kwargs)
+        self.data = self._get_data()
+
+    @observe('color_mapping')
+    def _updata_data(self, change):
+        self.data = self._get_data()
+
+    def _get_data(self):
+        self.values = list(self.gradient.keys())
+        self.colors = list(self.gradient.values())
+        self.vmin = self.values[0]
+        self.vmax = self.values[len(self.values) - 1]
+        self.colormap = LinearColormap(self.colors, vmin=self.vmin, vmax=self.vmax)
 
 
 class VectorTileLayer(Layer):