This is the code for Chapter 11, Figure 14 from D3.js in Action demonstrating d3.svg.brush() XY-brushing that uses d3.geom.quadtree() to dramatically improve spatial query performance.
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Ch. 11, Fig. 14 - D3.js in Action
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| <html> | |
| <head> | |
| <title>D3 in Action Chapter 11 - Example 8</title> | |
| <meta charset="utf-8" /> | |
| <script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.5/d3.min.js"></script> | |
| </head> | |
| <style> | |
| body, html { | |
| margin: 0; | |
| } | |
| canvas { | |
| position: absolute; | |
| width: 500px; | |
| height: 500px; | |
| } | |
| svg { | |
| position: absolute; | |
| width:500px; | |
| height:500px; | |
| } | |
| path.country { | |
| fill: gray; | |
| stroke-width: 1; | |
| stroke: black; | |
| opacity: .5; | |
| } | |
| path.sample { | |
| stroke: black; | |
| stroke-width: 1px; | |
| fill: red; | |
| fill-opacity: .5; | |
| } | |
| line.link { | |
| stroke-width: 1px; | |
| stroke: black; | |
| stroke-opacity: .5; | |
| } | |
| circle.node { | |
| fill: red; | |
| stroke: white; | |
| stroke-width: 1px; | |
| } | |
| circle.xy { | |
| fill: pink; | |
| stroke: black; | |
| stroke-width: 1px; | |
| } | |
| rect.extent { | |
| fill-opacity:.1; | |
| stroke: black; | |
| stroke-width: 1px; | |
| } | |
| </style> | |
| <body> | |
| <canvas height="500" width="500"></canvas> | |
| <div id="viz"> | |
| <svg></svg> | |
| </div> | |
| </body> | |
| <footer> | |
| <script> | |
| sampleData = d3.range(10000).map(function(d) { | |
| var datapoint = {}; | |
| datapoint.id = "Sample Node " + d; | |
| datapoint.x = Math.random() * 500; | |
| datapoint.y = Math.random() * 500; | |
| return datapoint; | |
| }) | |
| quadtree = d3.geom.quadtree() | |
| .extent([[0,0], [500,500]]) | |
| .x(function(d) {return d.x}) | |
| .y(function(d) {return d.y}); | |
| quadData = quadtree(sampleData); | |
| d3.select("svg").selectAll("circle").data(sampleData) | |
| .enter() | |
| .append("circle") | |
| .attr("r", 3) | |
| .attr("cx", function(d) {return d.x}) | |
| .attr("cy", function(d) {return d.y}) | |
| .style("fill", "pink") | |
| .style("stroke", "black") | |
| .style("stroke-width", "1px") | |
| var brush = d3.svg.brush() | |
| .x(d3.scale.identity().domain([0, 500])) | |
| .y(d3.scale.identity().domain([0, 500])) | |
| .on("brush", brushed); | |
| d3.select("svg").call(brush); | |
| function brushed() { | |
| var e = brush.extent(); | |
| d3.selectAll("circle").filter(function(d) {return d.selected}).style("fill", "pink").each(function(d) {d.selected = false}) | |
| quadData.visit(function(node,x1,y1,x2,y2) { | |
| if (node.point) { | |
| if (node.point.x >= e[0][0] && node.point.x <= e[1][0] && node.point.y >= e[0][1] && node.point.y <= e[1][1]) { | |
| node.point.selected = true; | |
| } | |
| } | |
| return x1 > e[1][0] || y1 > e[1][1] || x2 < e[0][0] || y2 < e[0][1]; | |
| }) | |
| d3.selectAll("circle").filter(function(d) {return d.selected}).style("fill", "darkred") | |
| } | |
| </script> | |
| </footer> | |
| </html> |
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