An example of d3-contour.
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March 6, 2019 05:07
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Contour Plot II
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| license: gpl-3.0 | |
| redirect: https://observablehq.com/@d3/contours |
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| <!DOCTYPE html> | |
| <svg width="960" height="500" stroke="#fff" stroke-width="0.5"></svg> | |
| <script src="https://d3js.org/d3.v4.min.js"></script> | |
| <script src="https://d3js.org/d3-contour.v1.min.js"></script> | |
| <script src="https://d3js.org/d3-scale-chromatic.v1.min.js"></script> | |
| <script> | |
| // Populate a grid of n×m values where -2 ≤ x ≤ 2 and -2 ≤ y ≤ 1. | |
| var n = 240, m = 125, values = new Array(n * m); | |
| for (var j = 0.5, k = 0; j < m; ++j) { | |
| for (var i = 0.5; i < n; ++i, ++k) { | |
| values[k] = goldsteinPrice(i / n * 4 - 2, 1 - j / m * 3); | |
| } | |
| } | |
| var svg = d3.select("svg"), | |
| width = +svg.attr("width"), | |
| height = +svg.attr("height"); | |
| var thresholds = d3.range(1, 21) | |
| .map(function(p) { return Math.pow(2, p); }); | |
| var contours = d3.contours() | |
| .size([n, m]) | |
| .thresholds(thresholds); | |
| var color = d3.scaleLog() | |
| .domain(d3.extent(thresholds)) | |
| .interpolate(function() { return d3.interpolateYlGnBu; }); | |
| svg.selectAll("path") | |
| .data(contours(values)) | |
| .enter().append("path") | |
| .attr("d", d3.geoPath(d3.geoIdentity().scale(width / n))) | |
| .attr("fill", function(d) { return color(d.value); }); | |
| // See https://en.wikipedia.org/wiki/Test_functions_for_optimization | |
| function goldsteinPrice(x, y) { | |
| return (1 + Math.pow(x + y + 1, 2) * (19 - 14 * x + 3 * x * x - 14 * y + 6 * x * x + 3 * y * y)) | |
| * (30 + Math.pow(2 * x - 3 * y, 2) * (18 - 32 * x + 12 * x * x + 48 * y - 36 * x * y + 27 * y * y)); | |
| } | |
| </script> |
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