39 lines
1.0 KiB
JavaScript
39 lines
1.0 KiB
JavaScript
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"use strict";
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var _ = require("../lodash");
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module.exports = initOrder;
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/*
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* Assigns an initial order value for each node by performing a DFS search
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* starting from nodes in the first rank. Nodes are assigned an order in their
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* rank as they are first visited.
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*
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* This approach comes from Gansner, et al., "A Technique for Drawing Directed
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* Graphs."
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*
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* Returns a layering matrix with an array per layer and each layer sorted by
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* the order of its nodes.
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*/
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function initOrder(g) {
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var visited = {};
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var simpleNodes = _.filter(g.nodes(), function(v) {
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return !g.children(v).length;
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});
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var maxRank = _.max(_.map(simpleNodes, function(v) { return g.node(v).rank; }));
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var layers = _.map(_.range(maxRank + 1), function() { return []; });
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function dfs(v) {
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if (_.has(visited, v)) return;
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visited[v] = true;
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var node = g.node(v);
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layers[node.rank].push(v);
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_.forEach(g.successors(v), dfs);
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}
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var orderedVs = _.sortBy(simpleNodes, function(v) { return g.node(v).rank; });
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_.forEach(orderedVs, dfs);
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return layers;
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}
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