79 lines
2.1 KiB
JavaScript
79 lines
2.1 KiB
JavaScript
import _ from 'lodash'
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import { Graph } from 'graphlibrary'
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import initOrder from './init-order'
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import crossCount from './cross-count'
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import sortSubgraph from './sort-subgraph'
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import buildLayerGraph from './build-layer-graph'
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import addSubgraphConstraints from './add-subgraph-constraints'
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import util from '../util'
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/*
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* Applies heuristics to minimize edge crossings in the graph and sets the best
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* order solution as an order attribute on each node.
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*
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* Pre-conditions:
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*
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* 1. Graph must be DAG
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* 2. Graph nodes must be objects with a "rank" attribute
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* 3. Graph edges must have the "weight" attribute
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*
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* Post-conditions:
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*
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* 1. Graph nodes will have an "order" attribute based on the results of the
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* algorithm.
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*/
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function order (g) {
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const maxRank = util.maxRank(g)
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const downLayerGraphs = buildLayerGraphs(g, _.range(1, maxRank + 1), 'inEdges')
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const upLayerGraphs = buildLayerGraphs(g, _.range(maxRank - 1, -1, -1), 'outEdges')
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let layering = initOrder(g)
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assignOrder(g, layering)
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let bestCC = Number.POSITIVE_INFINITY
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let best
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for (let i = 0, lastBest = 0; lastBest < 4; ++i, ++lastBest) {
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sweepLayerGraphs(i % 2 ? downLayerGraphs : upLayerGraphs, i % 4 >= 2)
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layering = util.buildLayerMatrix(g)
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const cc = crossCount(g, layering)
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if (cc < bestCC) {
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lastBest = 0
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best = _.cloneDeep(layering)
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bestCC = cc
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}
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}
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assignOrder(g, best)
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}
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function buildLayerGraphs (g, ranks, relationship) {
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return _.map(ranks, function (rank) {
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return buildLayerGraph(g, rank, relationship)
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})
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}
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function sweepLayerGraphs (layerGraphs, biasRight) {
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const cg = new Graph()
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_.forEach(layerGraphs, function (lg) {
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const root = lg.graph().root
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const sorted = sortSubgraph(lg, root, cg, biasRight)
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_.forEach(sorted.vs, function (v, i) {
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lg.node(v).order = i
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})
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addSubgraphConstraints(lg, cg, sorted.vs)
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})
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}
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function assignOrder (g, layering) {
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_.forEach(layering, function (layer) {
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_.forEach(layer, function (v, i) {
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g.node(v).order = i
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})
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})
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}
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export default order
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