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Recaman Sequence
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| license: mit |
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| <script src="https://d3js.org/d3.v5.min.js"></script> | |
| <svg width="960" height="500"></svg> | |
| <script> | |
| var n = 60; | |
| var curr = 0; | |
| var seq = [curr]; | |
| for (var i = 1; i < n; i++) { | |
| var next = curr - i; | |
| if (next < 0 || seq.includes(next)) { | |
| curr = curr + i; | |
| seq.push(curr); | |
| } else { | |
| curr = next; | |
| seq.push(next); | |
| } | |
| } | |
| console.log(seq); | |
| var data = []; | |
| var sign = 1; | |
| for (var i = 0; i < n - 1; i++) { | |
| var center = (seq[i] + seq[i+1]) / 2; | |
| var radius = Math.abs(seq[i] - seq[i+1]) / 2; | |
| var dir = Math.sign(seq[i+1] - seq[i]); | |
| data.push({center: center, radius: radius, sign: sign, dir: dir}); | |
| sign = -sign; | |
| } | |
| console.log(data); | |
| var svg = d3.select("svg"), | |
| width = +svg.attr("width"), | |
| height = +svg.attr("height"), | |
| g = svg.append("g"); | |
| var x = d3.scaleLinear().range([0, width]).domain([0, d3.max(seq)]) | |
| var arc = d3.arc() | |
| .innerRadius(function(d) { return x(d.radius)}) | |
| .outerRadius(function(d) { return x(d.radius)}) | |
| .endAngle(function(d) { return d.dir * d.sign * (Math.PI / 2) + (d.sign - 1) * Math.PI/2}) | |
| .startAngle(function(d) { return -d.dir * d.sign * (Math.PI /2) + (d.sign - 1) * Math.PI/2}); | |
| var DURATION = 300; | |
| g.selectAll('path') | |
| .data(data) | |
| .enter() | |
| .append('path') | |
| .attr("stroke", "steelblue") | |
| .attr("stroke-width", "2") | |
| .attr("d", arc) | |
| .attr("transform", function(d) { return "translate(" + x(d.center) + ",240)"}) | |
| .attr("stroke-dasharray", function(d) { return this.getTotalLength() + ", " + this.getTotalLength(); }) | |
| .attr("stroke-dashoffset", function(d) { return this.getTotalLength(); }) | |
| .transition() | |
| .delay(function(d, i) { return i * DURATION;}) | |
| .duration(DURATION * 2) | |
| .ease(d3.easeLinear) | |
| .attr("stroke-dashoffset", 0); | |
| </script> |
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