121 lines
3.1 KiB
JavaScript
121 lines
3.1 KiB
JavaScript
var bbox = require('@turf/bbox'),
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point = require('@turf/helpers').point;
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/**
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* Takes a {@link Feature} or {@link FeatureCollection} and returns the absolute center point of all features.
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*
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* @name center
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* @param {(Feature|FeatureCollection)} layer input features
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* @return {Feature<Point>} a Point feature at the absolute center point of all input features
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* @addToMap features, centerPt
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* @example
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* var features = {
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* "type": "FeatureCollection",
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* "features": [
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* {
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* "type": "Feature",
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* "properties": {},
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* "geometry": {
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* "type": "Point",
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* "coordinates": [-97.522259, 35.4691]
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* }
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* }, {
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* "type": "Feature",
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* "properties": {},
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* "geometry": {
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* "type": "Point",
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* "coordinates": [-97.502754, 35.463455]
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* }
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* }, {
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* "type": "Feature",
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* "properties": {},
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* "geometry": {
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* "type": "Point",
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* "coordinates": [-97.508269, 35.463245]
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* }
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* }, {
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* "type": "Feature",
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* "properties": {},
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* "geometry": {
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* "type": "Point",
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* "coordinates": [-97.516809, 35.465779]
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* }
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* }, {
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* "type": "Feature",
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* "properties": {},
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* "geometry": {
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* "type": "Point",
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* "coordinates": [-97.515372, 35.467072]
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* }
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* }, {
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* "type": "Feature",
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* "properties": {},
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* "geometry": {
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* "type": "Point",
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* "coordinates": [-97.509363, 35.463053]
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* }
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* }, {
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* "type": "Feature",
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* "properties": {},
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* "geometry": {
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* "type": "Point",
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* "coordinates": [-97.511123, 35.466601]
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* }
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* }, {
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* "type": "Feature",
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* "properties": {},
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* "geometry": {
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* "type": "Point",
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* "coordinates": [-97.518547, 35.469327]
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* }
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* }, {
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* "type": "Feature",
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* "properties": {},
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* "geometry": {
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* "type": "Point",
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* "coordinates": [-97.519706, 35.469659]
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* }
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* }, {
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* "type": "Feature",
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* "properties": {},
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* "geometry": {
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* "type": "Point",
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* "coordinates": [-97.517839, 35.466998]
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* }
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* }, {
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* "type": "Feature",
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* "properties": {},
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* "geometry": {
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* "type": "Point",
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* "coordinates": [-97.508678, 35.464942]
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* }
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* }, {
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* "type": "Feature",
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* "properties": {},
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* "geometry": {
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* "type": "Point",
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* "coordinates": [-97.514914, 35.463453]
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* }
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* }
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* ]
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* };
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*
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* var centerPt = turf.center(features);
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* centerPt.properties['marker-size'] = 'large';
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* centerPt.properties['marker-color'] = '#000';
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*
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* var resultFeatures = features.features.concat(centerPt);
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* var result = {
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* "type": "FeatureCollection",
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* "features": resultFeatures
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* };
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*
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* //=result
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*/
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module.exports = function (layer) {
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var ext = bbox(layer);
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var x = (ext[0] + ext[2]) / 2;
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var y = (ext[1] + ext[3]) / 2;
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return point([x, y]);
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};
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