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Census dotmap using 1.) censusreporter.org for data, and 2.) turf.js for random points within a polygon
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| <!DOCTYPE html> | |
| <html> | |
| <head> | |
| <meta charset=utf-8 /> | |
| <title>turfjs census dotmap</title> | |
| <meta name='viewport' content='initial-scale=1,maximum-scale=1,user-scalable=no' /> | |
| <script src='https://api.tiles.mapbox.com/mapbox.js/v2.1.9/mapbox.js'></script> | |
| <link href='https://api.tiles.mapbox.com/mapbox.js/v2.1.9/mapbox.css' rel='stylesheet' /> | |
| <style> | |
| body { margin:0; padding:0;} | |
| #map { position:absolute; top:0; bottom:0; width:100%; } | |
| </style> | |
| </head> | |
| <body> | |
| <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.4/jquery.min.js"></script> | |
| <script src='https://api.tiles.mapbox.com/mapbox.js/plugins/turf/v2.0.2/turf.min.js'></script> | |
| <div id='map'></div> | |
| <script> | |
| // specify census geoid - grab one here: http://censusreporter.org/ | |
| geoId = '15000US080470138003'; | |
| // get the polygon and population | |
| $.getJSON('https://api.censusreporter.org/1.0/geo/tiger2013/' + geoId + '?geom=true', function(data) { | |
| var block = JSON.parse(JSON.stringify(data)); | |
| // define the map and center on the polygon | |
| L.mapbox.accessToken = 'pk.eyJ1IjoiZmFyYWRheTIiLCJhIjoiTUVHbDl5OCJ9.buFaqIdaIM3iXr1BOYKpsQ'; | |
| var map = L.mapbox.map('map', 'faraday2.5905fe9b') | |
| .fitBounds(L.geoJson(block).getBounds()); | |
| // style for the polygon | |
| var polyStyle = { | |
| color: "#351f72", | |
| weight: 2, | |
| fillOpacity: 0, | |
| opacity: 0.8 | |
| }; | |
| // add the polygon to the map | |
| var blockFeature = L.geoJson(block, { | |
| style: polyStyle | |
| }); | |
| blockFeature.addTo(map); | |
| // create a bbox object for the polygon | |
| var blockBox = [blockFeature.getBounds()._southWest.lng,blockFeature.getBounds()._southWest.lat,blockFeature.getBounds()._northEast.lng,blockFeature.getBounds()._northEast.lat]; | |
| // style for the population points | |
| var markerStyle = { | |
| radius: 1.4, | |
| fillColor: "#634ea0", | |
| color: "#000", | |
| weight: 0, | |
| opacity: 0, | |
| fillOpacity: 0.7 | |
| }; | |
| // add the population of the feature | |
| var randomCount = block.properties.population; | |
| // increment up to the population count | |
| for (var i = 0; i < randomCount; i++) { | |
| // add a random point within the polygon's bbox | |
| var point = turf.random('points', 1, { | |
| bbox: blockBox | |
| }); | |
| // check to see if the point is within the polygon itself; | |
| // if not, decrement the count and try again | |
| if (turf.inside(point.features[0], block) == false ) { | |
| i = i - 1; | |
| continue; | |
| } | |
| // if the point is inside the polygon, add it to the map | |
| L.geoJson(point, { | |
| pointToLayer: function (feature, latlng) { | |
| return L.circleMarker(latlng, markerStyle); | |
| } | |
| }).addTo(map); | |
| } | |
| }); | |
| </script> | |
| </body> | |
| </html> |
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