add densitymapbox attributes

Author: etpinard

Diff for: src/traces/densitymapbox/attributes.js

@@ -0,0 +1,93 @@
+/**
+* Copyright 2012-2019, Plotly, Inc.
+* All rights reserved.
+*
+* This source code is licensed under the MIT license found in the
+* LICENSE file in the root directory of this source tree.
+*/
+
+'use strict';
+
+var colorScaleAttrs = require('../../components/colorscale/attributes');
+var hovertemplateAttrs = require('../../components/fx/hovertemplate_attributes');
+var plotAttrs = require('../../plots/attributes');
+var scatterMapboxAttrs = require('../scattermapbox/attributes');
+
+var extendFlat = require('../../lib/extend').extendFlat;
+
+/*
+ * - https://docs.mapbox.com/help/tutorials/make-a-heatmap-with-mapbox-gl-js/
+ * - https://docs.mapbox.com/mapbox-gl-js/example/heatmap-layer/
+ * - https://docs.mapbox.com/mapbox-gl-js/style-spec/#layers-heatmap
+ * - https://blog.mapbox.com/introducing-heatmaps-in-mapbox-gl-js-71355ada9e6c
+ *
+ * Gotchas:
+ * - https://github.com/mapbox/mapbox-gl-js/issues/6463
+ * - https://github.com/mapbox/mapbox-gl-js/issues/6112
+ */
+
+/*
+ *
+ * In mathematical terms, Mapbox GL heatmaps are a bivariate (2D) kernel density
+ * estimation with a Gaussian kernel. It means that each data point has an area
+ * of “influence” around it (called a kernel) where the numerical value of
+ * influence (which we call density) decreases as you go further from the point.
+ * If we sum density values of all points in every pixel of the screen, we get a
+ * combined density value which we then map to a heatmap color.
+ *
+ */
+
+module.exports = extendFlat({
+    lon: scatterMapboxAttrs.lon,
+    lat: scatterMapboxAttrs.lat,
+
+    z: {
+        valType: 'data_array',
+        editType: 'calc',
+        description: [
+            'Sets the points\' weight.',
+            'For example, a value of 10 would be equivalent to having 10 points of weight 1',
+            'in the same spot'
+        ].join(' ')
+    },
+
+    radius: {
+        valType: 'number',
+        role: 'info',
+        editType: 'plot',
+        arrayOk: true,
+        min: 1,
+        dflt: 30,
+        description: [
+            'Sets the radius of influence of one `lon` / `lat` point in pixels.',
+            'Increasing the value makes the densitymapbox trace smoother, but less detailed.'
+        ].join(' ')
+    },
+
+    below: {
+        valType: 'string',
+        role: 'info',
+        editType: 'plot',
+        description: [
+            'Determines if the densitymapbox trace will be inserted',
+            'before the layer with the specified ID.',
+            'By default, densitymapbox traces are placed below the first',
+            'layer of type symbol',
+            'If set to \'\',',
+            'the layer will be inserted above every existing layer.'
+        ].join(' ')
+    },
+
+    text: scatterMapboxAttrs.text,
+    hovertext: scatterMapboxAttrs.hovertext,
+
+    hoverinfo: extendFlat({}, plotAttrs.hoverinfo, {
+        flags: ['lon', 'lat', 'z', 'text', 'name']
+    }),
+    hovertemplate: hovertemplateAttrs()
+},
+    colorScaleAttrs('', {
+        cLetter: 'z',
+        editTypeOverride: 'calc'
+    })
+);