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Voronoi CABA

A demonstration of how to calculate the areas of Voronoi regions clipped by geographic features using D3.

[D3’s implementation](Sutherland–Hodgman algorithm) of the Sutherland–Hodgman algorithm only works for convex clip polygons, but we exploit the fact that Voronoi regions are guaranteed to be convex, and use each Voronoi region as a clip polygon, with the projected geographic boundary as a subject polygon.

In response to a question by Gonzalo Bellver.

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id nombre direccion comuna barrio circunscri longitude latitude geojson
1 Comisaría 1 451 LAVALLE COMUNA 1 SAN NICOLAS I -58.3732 -34.6019 {"type":"Point","coordinates":[-58.37324,-34.60191]}
2 Comisaría 2 1050 PERU COMUNA 1 SAN TELMO I -58.374 -34.6202 {"type":"Point","coordinates":[-58.37405,-34.62019]}
3 Comisaría 3 1560 TUCUMAN COMUNA 1 SAN NICOLAS I -58.3889 -34.6019 {"type":"Point","coordinates":[-58.3889,-34.60194]}
4 Comisaría 4 770 TACUARI COMUNA 1 MONSERRAT I -58.3786 -34.6172 {"type":"Point","coordinates":[-58.37858,-34.61716]}
5 Comisaría 5 1958 LAVALLE COMUNA 3 BALVANERA II -58.3948 -34.6034 {"type":"Point","coordinates":[-58.39479,-34.60342]}
6 Comisaría 7 2625 LAVALLE COMUNA 3 BALVANERA II -58.404 -34.6032 {"type":"Point","coordinates":[-58.40401,-34.60321]}
7 Comisaría 9 471 BILLINGHURST COMUNA 5 ALMAGRO II -58.4156 -34.6044 {"type":"Point","coordinates":[-58.41556,-34.60443]}
8 Comisaría 12 1454 VALLE COMUNA 6 CABALLITO VI -58.4481 -34.6268 {"type":"Point","coordinates":[-58.44809,-34.62678]}
9 Comisaría 14 1419 BOLIVAR COMUNA 1 SAN TELMO I -58.3729 -34.6246 {"type":"Point","coordinates":[-58.37288,-34.62456]}
10 Comisaría 15 1156 SUIPACHA COMUNA 1 RETIRO III -58.3802 -34.5946 {"type":"Point","coordinates":[-58.38018,-34.59464]}
11 Comisaría 17 1861 LAS HERAS GRAL. COMUNA 2 RECOLETA III -58.3924 -34.5911 {"type":"Point","coordinates":[-58.39236,-34.59114]}
12 Comisaría 24 456 PINZON COMUNA 4 BOCA IV -58.3606 -34.6342 {"type":"Point","coordinates":[-58.36059,-34.63417]}
13 Comisaría 26 861 MONTES DE OCA MANUEL COMUNA 4 BARRACAS IV -58.3749 -34.6381 {"type":"Point","coordinates":[-58.37491,-34.63806]}
14 Comisaría 28 170 VELEZ SARSFIELD COMUNA 4 BARRACAS IV -58.39 -34.6362 {"type":"Point","coordinates":[-58.38997,-34.63617]}
15 Comisaría 30 1850 CALIFORNIA COMUNA 4 BARRACAS IV -58.3747 -34.6473 {"type":"Point","coordinates":[-58.37473,-34.64729]}
16 Comisaría 32 2724 CASEROS COMUNA 4 PARQUE PATRICIOS IV -58.4008 -34.6365 {"type":"Point","coordinates":[-58.40083,-34.63645]}
17 Comisaría 33 2263 MENDOZA COMUNA 13 BELGRANO V -58.4563 -34.5601 {"type":"Point","coordinates":[-58.45628,-34.56014]}
18 Comisaría 35 3145 CUBA COMUNA 13 NUÑEZ VII -58.4633 -34.5514 {"type":"Point","coordinates":[-58.46333,-34.55138]}
19 Comisaría 36 3405 PEDERNERA COMUNA 8 VILLA SOLDATI VIII -58.432 -34.6604 {"type":"Point","coordinates":[-58.43198,-34.66039]}
20 Comisaría 40 3748 REMEDIOS COMUNA 9 PARQUE AVELLANEDA VIII -58.4763 -34.6415 {"type":"Point","coordinates":[-58.47634,-34.64146]}
21 Comisaría 41 1800 BUFANO ALFREDO R. COMUNA 11 VILLA GRAL. MITRE VII -58.473 -34.6111 {"type":"Point","coordinates":[-58.47299,-34.61112]}
22 Comisaría 42 2343 DE LA TORRE LISANDRO COMUNA 9 MATADEROS VIII -58.5012 -34.662 {"type":"Point","coordinates":[-58.50117,-34.66199]}
23 Comisaría 43 453 CHIVILCOY COMUNA 10 FLORESTA VII -58.4838 -34.6288 {"type":"Point","coordinates":[-58.48378,-34.62881]}
24 Comisaría 47 4254 NAZCA COMUNA 12 VILLA PUEYRREDON VII -58.4994 -34.5897 {"type":"Point","coordinates":[-58.49937,-34.58971]}
25 Comisaría 48 4347 LEGUIZAMON MARTINIANO COMUNA 8 VILLA LUGANO VIII -58.475 -34.679 {"type":"Point","coordinates":[-58.47503,-34.67904]}
26 Comisaría 49 3045 MACHAIN COMUNA 12 VILLA URQUIZA VII -58.4825 -34.5651 {"type":"Point","coordinates":[-58.48253,-34.56515]}
27 Comisaría 45 4154 CUBAS JOSE COMUNA 11 VILLA DEVOTO VII -58.5156 -34.5983 {"type":"Point","coordinates":[-58.51561,-34.59831]}
28 Comisaría 46 2550 DE LOS INMIGRANTES COMUNA 1 RETIRO I -58.3694 -34.5843 {"type":"Point","coordinates":[-58.36945,-34.58425]}
29 Comisaría 19 2844 CHARCAS COMUNA 2 RECOLETA III -58.4067 -34.5941 {"type":"Point","coordinates":[-58.40672,-34.59408]}
30 Comisaría 23 4000 SANTA FE COMUNA 14 PALERMO III -58.4201 -34.5825 {"type":"Point","coordinates":[-58.42014,-34.58252]}
31 Comisaría 25 1350 SCALABRINI ORTIZ RAUL COMUNA 14 PALERMO V -58.4276 -34.5924 {"type":"Point","coordinates":[-58.42761,-34.59244]}
32 Comisaría 31 232 CABILDO COMUNA 14 PALERMO V -58.439 -34.5733 {"type":"Point","coordinates":[-58.43896,-34.57331]}
33 Comisaría 37 4367 JURAMENTO COMUNA 12 VILLA URQUIZA V -58.4758 -34.5731 {"type":"Point","coordinates":[-58.47582,-34.57312]}
34 Comisaría 21 2373 ALVAREZ JULIAN COMUNA 14 PALERMO III -58.4159 -34.5877 {"type":"Point","coordinates":[-58.41593,-34.58773]}
35 Comisaría 8 550 URQUIZA GRAL. COMUNA 3 BALVANERA II -58.4092 -34.6171 {"type":"Point","coordinates":[-58.40921,-34.61705]}
36 Comisaría 6 1931 VENEZUELA COMUNA 3 BALVANERA II -58.3937 -34.6149 {"type":"Point","coordinates":[-58.39368,-34.61489]}
37 Comisaría 10 1250 MUÑIZ COMUNA 5 BOEDO VI -58.4249 -34.6286 {"type":"Point","coordinates":[-58.42493,-34.62864]}
38 Comisaría 13 1548 AVELLANEDA COMUNA 6 CABALLITO VI -58.4532 -34.6204 {"type":"Point","coordinates":[-58.45322,-34.62038]}
39 Comisaría 11 5152 DIAZ VELEZ COMUNA 6 CABALLITO VI -58.4395 -34.609 {"type":"Point","coordinates":[-58.4395,-34.60898]}
40 Comisaría 22 640 HUERGO ING. COMUNA 1 PUERTO MADERO I -58.3666 -34.615 {"type":"Point","coordinates":[-58.36659,-34.61497]}
41 Comisaría 20 1345 CATAMARCA COMUNA 3 SAN CRISTOBAL II -58.4032 -34.626 {"type":"Point","coordinates":[-58.40323,-34.62603]}
42 Comisaría 18 1757 SAN JUAN COMUNA 1 CONSTITUCION II -58.3908 -34.6225 {"type":"Point","coordinates":[-58.39081,-34.62251]}
43 Comisaría 16 1224 SAN JOSE COMUNA 1 CONSTITUCION IV -58.3856 -34.6227 {"type":"Point","coordinates":[-58.38561,-34.62267]}
44 Comisaría 52 CAFAYATE & DIAZ ANA COMUNA 8 VILLA LUGANO VIII -58.4694 -34.6839 {"type":"Point","coordinates":[-58.46942,-34.68393]}
45 Comisaría 27 645 CAMARGO COMUNA 15 VILLA CRESPO V -58.4411 -34.5993 {"type":"Point","coordinates":[-58.44108,-34.59932]}
46 Comisaría 29 4350 DUMONT SANTOS COMUNA 15 CHACARITA V -58.4526 -34.5922 {"type":"Point","coordinates":[-58.45263,-34.59216]}
47 Comisaría 34 456 QUILMES COMUNA 4 NUEVA POMPEYA VI -58.4172 -34.6448 {"type":"Point","coordinates":[-58.41716,-34.64479]}
48 Comisaría 38 258 BONORINO ESTEBAN CNEL. COMUNA 7 FLORES VI -58.4583 -34.6309 {"type":"Point","coordinates":[-58.45826,-34.63092]}
49 Comisaría 39 5437 OLAZABAL COMUNA 12 VILLA URQUIZA VII -58.4901 -34.5787 {"type":"Point","coordinates":[-58.49006,-34.57869]}
50 Comisaría 44 726 PORCEL DE PERALTA MANUEL COMUNA 10 VERSALLES VIII -58.524 -34.6295 {"type":"Point","coordinates":[-58.52404,-34.62954]}
51 Comisaría 50 2738 GAONA COMUNA 7 FLORES VI -58.4648 -34.6161 {"type":"Point","coordinates":[-58.46482,-34.61611]}
52 Comisaría 51 2081 ARTILLEROS COMUNA 13 BELGRANO V -58.4441 -34.5548 {"type":"Point","coordinates":[-58.44407,-34.55482]}
53 Comisaría 53 2961 REPUBLICA ARABE-SIRIA COMUNA 14 PALERMO III -58.4137 -34.5813 {"type":"Point","coordinates":[-58.41366,-34.58127]}
<!DOCTYPE html>
<meta charset="utf-8">
<style>
svg {
fill: white;
}
path {
stroke-linejoin: round;
}
.points {
fill: black;
}
.subunit {
fill: none;
stroke: #999;
stroke-size: 1px;
}
.voronoi {
fill: none;
fill-opacity: 0.5;
stroke: white;
stroke-width: .5px;
}
</style>
<body>
<script src="http://d3js.org/d3.v3.min.js"></script>
<script src="http://d3js.org/queue.v1.min.js"></script>
<script src="http://d3js.org/topojson.v1.min.js"></script>
<script>
var width = 960,
height = 500;
var fill = d3.scale.linear()
.domain([0, 10000])
.range(["#F14E2F","#333399","#1DBDFF"]);
var projection = d3.geo.mercator()
.scale(132000)
.center([-58.45000,-34.61600]);
var path = d3.geo.path()
.projection(projection)
.pointRadius(1.5);
var voronoi = d3.geom.voronoi();
var svg = d3.select("body").append("svg")
.attr("width", width)
.attr("height", height);
queue()
.defer(d3.json, "caba.json")
.defer(d3.csv, "comisarias.csv")
.await(ready);
function ready(error, caba, comisarias) {
var limits = topojson.feature(caba, caba.objects.limites);
var exterior = projectLineString(limits, projection);
svg.append("path")
.datum(limits)
.attr("class", "limits")
.attr("d", path);
svg.append("path")
.datum(topojson.mesh(caba, caba.objects.barrios))
.attr("class", "subunit")
.attr("d", path);
var coordinates = comisarias.map(function(d) { return [+d.longitude, +d.latitude]; });
svg.append("path")
.datum({type: "MultiPoint", coordinates: coordinates})
.attr("class", "points")
.attr("d", path);
svg.append("g")
.attr("class", "land")
.selectAll(".voronoi")
.data(voronoi(coordinates.map(projection)).map(function(d) {
// Each voronoi region is a convex polygon, therefore we can use
// d3.geom.polygon.clip, treating each regino as a clip region, with the
// projected “exterior” as a subject polygon.
return d3.geom.polygon(d).clip(exterior.slice());
}))
.enter().append("path")
.attr("class", "voronoi")
.style("fill", function(d) { return fill(Math.abs(d3.geom.polygon(d).area())); })
.attr("d", polygon);
}
function polygon(d) {
return "M" + d.join("L") + "Z";
}
// Extracts a single LineString from the given feature, projected (and
// resampled) using the given projection.
function projectLineString(feature, projection) {
var line;
d3.geo.stream(feature, projection.stream({
polygonStart: noop,
polygonEnd: noop,
lineStart: function() { line = []; },
lineEnd: noop,
point: function(x, y) { line.push([x, y]); },
sphere: noop
}));
return line;
}
function noop() {}
</script>
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