This is the code for Chapter 7, Figure 20 from D3.js in Action that demonstrates how to use d3.geo.tile() to create maps using terrain tiles.
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Ch. 7, Fig. 20 - D3.js in Action
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| label | population | country | x | y | |
|---|---|---|---|---|---|
| San Francisco | 750000 | USA | 37 | -122 | |
| Fresno | 500000 | USA | 36 | -119 | |
| Lahore | 12500000 | Pakistan | 31 | 74 | |
| Karachi | 13000000 | Pakistan | 24 | 67 | |
| Rome | 2500000 | Italy | 41 | 12 | |
| Naples | 1000000 | Italy | 40 | 14 | |
| Rio | 12300000 | Brazil | -22 | -43 | |
| Sao Paolo | 12300000 | Brazil | -23 | -46 |
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| <html> | |
| <head> | |
| <title>D3 in Action Chapter 7 - Example 10</title> | |
| <meta charset="utf-8" /> | |
| <script src="https://d3js.org/d3.geo.projection.v0.min.js" type="text/JavaScript"></script> | |
| <script src="https://d3js.org/queue.v1.min.js" type="text/JavaScript"></script> | |
| <script src="http://d3js.org/colorbrewer.v1.min.js" type="text/JavaScript"></script> | |
| <script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.5/d3.min.js"></script> | |
| <script src="https://cdnjs.cloudflare.com/ajax/libs/topojson/1.6.19/topojson.min.js"></script> | |
| <script src="tile.js" type="text/JavaScript"></script> | |
| </head> | |
| <style> | |
| svg { | |
| height: 500px; | |
| width: 500px; | |
| border: 1px solid gray; | |
| } | |
| .countries { | |
| fill: red; | |
| fill-opacity: .5; | |
| stroke: black; | |
| stroke-width: 1px; | |
| } | |
| </style> | |
| <body> | |
| <div id="viz"> | |
| <svg> | |
| </svg> | |
| </div> | |
| </body> | |
| <footer> | |
| <script> | |
| var width = 500, | |
| height = 500; | |
| d3.select("svg").append("g").attr("id", "tiles"); | |
| d3.select("svg").append("g").attr("id", "vectors"); | |
| queue() | |
| .defer(d3.json, "world.topojson") | |
| .defer(d3.csv, "cities.csv") | |
| .await(function(error, file1, file2) { createMap(file1, file2); }); | |
| function createMap(countries1, cities) { | |
| var countries = topojson.feature(countries1, countries1.objects.countries); | |
| var tile = d3.geo.tile() | |
| .size([width, height]); | |
| var projection = d3.geo.mercator() | |
| .scale(120) | |
| .translate([width / 2, height / 2]); | |
| var center = projection([12, 42]); | |
| geoPath = d3.geo.path().projection(projection); | |
| var zoom = d3.behavior.zoom() | |
| .scale(projection.scale() * 2 * Math.PI) | |
| .translate([width - center[0], height - center[1]]) | |
| .on("zoom", redraw); | |
| d3.select("svg").call(zoom); | |
| redraw(); | |
| featureSize = d3.extent(countries.features, function(d) {return geoPath.area(d)}); | |
| countryColor = d3.scale.quantize().domain(featureSize).range(colorbrewer.Reds[7]); | |
| d3.select("#vectors").selectAll("path.countries").data(countries.features) | |
| .enter() | |
| .append("path") | |
| .attr("d", geoPath) | |
| .attr("class", "countries") | |
| .style("fill", function(d) {return countryColor(geoPath.area(d))}) | |
| .style("stroke-width", 1) | |
| .style("stroke", "black") | |
| .style("opacity", .5) | |
| .style("display", function(d,i) {return i%2 == 0 ? "none" : "block"}) | |
| d3.select("#vectors").selectAll("circle").data(cities) | |
| .enter() | |
| .append("circle") | |
| .style("fill", "black") | |
| .style("stroke", "white") | |
| .style("stroke-width", 1) | |
| .attr("r", 3) | |
| .attr("cx", function(d) {return projection([d.y,d.x])[0]}) | |
| .attr("cy", function(d) {return projection([d.y,d.x])[1]}) | |
| redraw(); | |
| function redraw() { | |
| var tiles = tile | |
| .scale(zoom.scale()) | |
| .translate(zoom.translate()) | |
| (); | |
| var image = d3.select("#tiles").attr("transform", "scale(" + tiles.scale + ")translate(" + tiles.translate + ")") | |
| .selectAll("image") | |
| .data(tiles, function(d) { return d; }); | |
| image.exit() | |
| .remove(); | |
| image.enter().append("image") | |
| .attr("xlink:href", function(d) { return "http://" + ["a", "b", "c", "d"][Math.random() * 4 | 0] + ".tiles.mapbox.com/v3/examples.map-zgrqqx0w/" + d[2] + "/" + d[0] + "/" + d[1] + ".png"; }) | |
| .attr("width", 1) | |
| .attr("height", 1) | |
| .attr("x", function(d) { return d[0]; }) | |
| .attr("y", function(d) { return d[1]; }); | |
| projection | |
| .scale(zoom.scale() / 2 / Math.PI) | |
| .translate(zoom.translate()); | |
| d3.selectAll("path.countries") | |
| .attr("d", geoPath); | |
| d3.selectAll("circle") | |
| .attr("cx", function(d) {return projection([d.y,d.x])[0]}) | |
| .attr("cy", function(d) {return projection([d.y,d.x])[1]}) | |
| } | |
| } | |
| </script> | |
| </footer> | |
| </html> |
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| d3.geo.tile = function() { | |
| var size = [960, 500], | |
| scale = 256, | |
| translate = [size[0] / 2, size[1] / 2], | |
| zoomDelta = 0; | |
| function tile() { | |
| var z = Math.max(Math.log(scale) / Math.LN2 - 8, 0), | |
| z0 = Math.round(z + zoomDelta), | |
| k = Math.pow(2, z - z0 + 8), | |
| origin = [(translate[0] - scale / 2) / k, (translate[1] - scale / 2) / k], | |
| tiles = [], | |
| cols = d3.range(Math.max(0, Math.floor(-origin[0])), Math.max(0, Math.ceil(size[0] / k - origin[0]))), | |
| rows = d3.range(Math.max(0, Math.floor(-origin[1])), Math.max(0, Math.ceil(size[1] / k - origin[1]))); | |
| rows.forEach(function(y) { | |
| cols.forEach(function(x) { | |
| tiles.push([x, y, z0]); | |
| }); | |
| }); | |
| tiles.translate = origin; | |
| tiles.scale = k; | |
| return tiles; | |
| } | |
| tile.size = function(_) { | |
| if (!arguments.length) return size; | |
| size = _; | |
| return tile; | |
| }; | |
| tile.scale = function(_) { | |
| if (!arguments.length) return scale; | |
| scale = _; | |
| return tile; | |
| }; | |
| tile.translate = function(_) { | |
| if (!arguments.length) return translate; | |
| translate = _; | |
| return tile; | |
| }; | |
| tile.zoomDelta = function(_) { | |
| if (!arguments.length) return zoomDelta; | |
| zoomDelta = +_; | |
| return tile; | |
| }; | |
| return tile; | |
| }; |
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