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36 lines
922 B
JavaScript
36 lines
922 B
JavaScript
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/* Inspired by Lee Byron's test data generator. */
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function stream_layers(n, m, o) {
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if (arguments.length < 3) o = 0;
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function bump(a) {
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var x = 1 / (.1 + Math.random()),
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y = 2 * Math.random() - .5,
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z = 10 / (.1 + Math.random());
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for (var i = 0; i < m; i++) {
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var w = (i / m - y) * z;
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a[i] += x * Math.exp(-w * w);
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}
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}
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return d3.range(n).map(function() {
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var a = [], i;
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for (i = 0; i < m; i++) a[i] = o + o * Math.random();
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for (i = 0; i < 5; i++) bump(a);
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return a.map(stream_index);
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});
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}
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/* Another layer generator using gamma distributions. */
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function stream_waves(n, m) {
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return d3.range(n).map(function(i) {
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return d3.range(m).map(function(j) {
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var x = 20 * j / m - i / 3;
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return 2 * x * Math.exp(-.5 * x);
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}).map(stream_index);
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});
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}
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function stream_index(d, i) {
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return {x: i, y: Math.max(0, d)};
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}
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