A test for the new topojson.merge functionality available in TopoJSON 1.6. The state boundaries are computed solely by merging county boundaries!
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February 9, 2016 01:57
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Merging Counties
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| license: gpl-3.0 |
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| <!DOCTYPE html> | |
| <meta charset="utf-8"> | |
| <style> | |
| path { | |
| stroke-linejoin: round; | |
| stroke-linecap: round; | |
| } | |
| .land { | |
| fill: #bbb; | |
| } | |
| .border { | |
| fill: none; | |
| } | |
| .border--static { | |
| stroke: #fff; | |
| } | |
| </style> | |
| <body> | |
| <script src="//d3js.org/d3.v3.min.js"></script> | |
| <script src="//d3js.org/topojson.v1.min.js"></script> | |
| <script> | |
| var width = 960, | |
| height = 600; | |
| var projection = d3.geo.albersUsa() | |
| .scale(1280) | |
| .translate([width / 2, height / 2]); | |
| var path = d3.geo.path() | |
| .projection(projection); | |
| var svg = d3.select("body").append("svg") | |
| .attr("width", width) | |
| .attr("height", height); | |
| d3.json("/mbostock/raw/4090846/us.json", function(error, us) { | |
| if (error) throw error; | |
| var delay = 0; | |
| svg.append("path") | |
| .datum(topojson.merge(us, us.objects.counties.geometries)) | |
| .attr("class", "land") | |
| .attr("d", path); | |
| var gStatic = svg.append("g") | |
| .attr("class", "border border--static"); | |
| var gAnimate = svg.append("g") | |
| .attr("class", "border border--animate"); | |
| gAnimate.selectAll("path") | |
| .data(d3.nest() | |
| .key(function(d) { return d.id / 1000 | 0; }) | |
| .sortKeys(function(a, b) { return a - b; }) | |
| .entries(us.objects.counties.geometries)) | |
| .enter().append("path") | |
| .attr("d", function(d) { return path(topojson.merge(us, d.values)); }) | |
| .each(function(d) { d.duration = (d.length = this.getTotalLength()) * 3; }) | |
| .style("stroke-width", "1.5px") | |
| .style("stroke-dasharray", function(d) { return "0," + d.length; }) | |
| .transition() | |
| .delay(function(d, i) { var delay1 = delay; delay += d.duration; return delay1; }) | |
| .duration(function(d) { return d.duration; }) | |
| .ease("linear") | |
| .each("start", function() { this.style.stroke = "#000"; }) | |
| .style("stroke-dasharray", function(d) { return d.length + "," + d.length; }) | |
| .each("end", function(d) { | |
| var id = +d.key; | |
| gStatic.append("path") | |
| .datum(topojson.mesh(us, us.objects.counties, function(a, b) { return a.id / 1000 ^ b.id / 1000 && ((a.id / 1000 | 0) === id || (b.id / 1000 | 0) === id); })) | |
| .attr("d", path); | |
| }) | |
| .transition() | |
| .duration(750) | |
| .style("stroke-opacity", 0) | |
| .remove(); | |
| }); | |
| d3.select(self.frameElement).style("height", height + "px"); | |
| </script> |
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