41 lines
1 KiB
JavaScript
41 lines
1 KiB
JavaScript
import constant from "./constant.js";
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export default function(y) {
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var strength = constant(0.1),
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nodes,
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strengths,
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yz;
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if (typeof y !== "function") y = constant(y == null ? 0 : +y);
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function force(alpha) {
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for (var i = 0, n = nodes.length, node; i < n; ++i) {
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node = nodes[i], node.vy += (yz[i] - node.y) * strengths[i] * alpha;
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}
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}
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function initialize() {
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if (!nodes) return;
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var i, n = nodes.length;
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strengths = new Array(n);
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yz = new Array(n);
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for (i = 0; i < n; ++i) {
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strengths[i] = isNaN(yz[i] = +y(nodes[i], i, nodes)) ? 0 : +strength(nodes[i], i, nodes);
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}
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}
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force.initialize = function(_) {
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nodes = _;
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initialize();
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};
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force.strength = function(_) {
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return arguments.length ? (strength = typeof _ === "function" ? _ : constant(+_), initialize(), force) : strength;
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};
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force.y = function(_) {
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return arguments.length ? (y = typeof _ === "function" ? _ : constant(+_), initialize(), force) : y;
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};
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return force;
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}
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