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@hepplerj
Last active Mar 27, 2017
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TopoJSON merge

Testing topojson.merge to merge multiple polygons into a single polygon.

<!DOCTYPE html>
<meta charset="utf-8">
<style>
.state {
fill: #ccc;
}
.state-boundary {
fill: none;
stroke: #fff;
}
.state.selected {
fill: orange;
stroke: #000;
}
</style>
<body>
<script src="http://d3js.org/d3.v3.min.js"></script>
<script src="http://d3js.org/topojson.v1.min.js"></script>
<script>
var width = 1024,
height = 768;
var path = d3.geo.path()
.projection(null);
var svg = d3.select("body").append("svg")
.attr("width", width)
.attr("height", height);
var selected = d3.set([
'ND', 'SD', 'NE', 'MN', 'IA', 'WI', 'IL', 'OH', 'MI', 'IN'
]);
d3.json("ne_50m_usa_canada.topojson", function(error, us) {
console.log(us);
svg.append("path")
.datum(topojson.feature(us, us.objects.usa_canada))
.attr("class", "state")
.attr("d", path);
svg.append("path")
.datum(topojson.mesh(us, us.objects.usa_canada, function(a, b) { return a !== b; }))
.attr("class", "state-boundary")
.attr("d", path);
svg.append("path")
.datum(topojson.merge(us, us.objects.usa_canada.geometries.filter(function(d) { return selected.has(d.id); })))
.attr("class", "state selected")
.attr("d", path);
});
d3.select(self.frameElement).style("height", height + "px");
</script>
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