mirror of https://gitee.com/bigwinds/arangodb
570 lines
17 KiB
JavaScript
570 lines
17 KiB
JavaScript
/*jshint strict: false */
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////////////////////////////////////////////////////////////////////////////////
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/// @brief Graph functionality
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///
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/// @file
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///
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/// DISCLAIMER
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///
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/// Copyright 2010-2012 triagens GmbH, Cologne, Germany
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///
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/// Licensed under the Apache License, Version 2.0 (the "License");
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/// you may not use this file except in compliance with the License.
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/// You may obtain a copy of the License at
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///
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/// http://www.apache.org/licenses/LICENSE-2.0
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///
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/// Unless required by applicable law or agreed to in writing, software
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/// distributed under the License is distributed on an "AS IS" BASIS,
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/// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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/// See the License for the specific language governing permissions and
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/// limitations under the License.
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///
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/// Copyright holder is triAGENS GmbH, Cologne, Germany
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///
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/// @author Dr. Frank Celler, Lucas Dohmen
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/// @author Copyright 2011-2012, triAGENS GmbH, Cologne, Germany
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////////////////////////////////////////////////////////////////////////////////
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var graph = require("@arangodb/graph-blueprint");
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var Graph = graph.Graph;
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var Vertex = graph.Vertex;
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function unite (l, r) {
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return r.concat(l.filter(function (element) {
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return (r.indexOf(element) === -1);
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}));
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}
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function intersect (l, r) {
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return l.filter(function (element) {
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return (r.indexOf(element) > -1);
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});
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}
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function removeLastOccurrenceOf (l, element) {
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return l.splice(l.lastIndexOf(element), 1);
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}
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////////////////////////////////////////////////////////////////////////////////
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/// @brief return the number of common neighbors
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///
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/// @FUN{@FA{vertex}.commonNeighborsWith(@FA{target_vertex}, @FA{options})}
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///
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////////////////////////////////////////////////////////////////////////////////
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Vertex.prototype.commonNeighborsWith = function (target_vertex, options) {
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var neighbor_set_one,
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neighbor_set_two,
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id_only,
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common_neighbors,
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all_neighbors,
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return_value;
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options = options || {};
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id_only = function (neighbor) {
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return neighbor.id;
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};
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if (typeof(target_vertex) !== 'object') {
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throw "<target_vertex> must be a vertex object";
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}
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neighbor_set_one = this.getNeighbors(options).map(id_only);
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neighbor_set_two = target_vertex.getNeighbors(options).map(id_only);
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common_neighbors = intersect(neighbor_set_one, neighbor_set_two);
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if ((options.listed !== undefined) && (options.listed === true)) {
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return_value = common_neighbors;
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}
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else if ((options.normalized !== undefined) && (options.normalized === true)) {
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all_neighbors = unite(neighbor_set_one, neighbor_set_two);
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return_value = (common_neighbors.length / all_neighbors.length);
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}
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else {
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return_value = common_neighbors.length;
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}
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return return_value;
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};
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////////////////////////////////////////////////////////////////////////////////
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/// @brief return the number of common properties
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///
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/// @FUN{@FA{vertex}.commonPropertiesWith(@FA{target_vertex}, @FA{options})}
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///
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////////////////////////////////////////////////////////////////////////////////
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Vertex.prototype.commonPropertiesWith = function (other_vertex, options) {
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var property_names,
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shared_properties = [],
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this_vertex = this,
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return_value;
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options = options || {};
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property_names = unite(this_vertex.getPropertyKeys(), other_vertex.getPropertyKeys());
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property_names.forEach(function (property) {
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if (this_vertex.getProperty(property) === other_vertex.getProperty(property)) {
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shared_properties.push(property);
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}
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});
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if ((options.listed !== undefined) && (options.listed === true)) {
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return_value = shared_properties;
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} else if ((options.normalized !== undefined) && (options.normalized === true)) {
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return_value = shared_properties.length / property_names.length;
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} else {
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return_value = shared_properties.length;
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}
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return return_value;
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};
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////////////////////////////////////////////////////////////////////////////////
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/// @brief find the shortest path to a certain vertex, return the ID
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///
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/// @FUN{@FA{vertex}.pathTo(@FA{target_vertex}, @FA{options})}
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///
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////////////////////////////////////////////////////////////////////////////////
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Vertex.prototype.pathTo = function (target_vertex, options) {
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if (typeof(target_vertex) !== 'object') {
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throw "<target_vertex> must be an object";
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}
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var predecessors = target_vertex.determinePredecessors(this, options || {});
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return (predecessors ? target_vertex.pathesForTree(predecessors) : []);
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};
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////////////////////////////////////////////////////////////////////////////////
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/// @brief find the shortest path and return the number of edges to the target vertex
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///
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/// @FUN{@FA{vertex}.distanceTo(@FA{target_vertex}, @FA{options})}
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///
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////////////////////////////////////////////////////////////////////////////////
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Vertex.prototype.distanceTo = function (target_vertex, options) {
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var predecessors = target_vertex.determinePredecessors(this, options || {}),
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current_vertex_id = target_vertex.getId(),
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count = 0;
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while (predecessors[current_vertex_id] !== undefined) {
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current_vertex_id = predecessors[current_vertex_id][0];
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count += 1;
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}
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if (current_vertex_id !== this.getId()) {
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count = Infinity;
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}
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return count;
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};
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////////////////////////////////////////////////////////////////////////////////
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/// @brief determine all the pathes to this node from source
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///
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/// @FUN{@FA{vertex}.determinePredecessors(@FA{source}, @FA{options})}
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///
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////////////////////////////////////////////////////////////////////////////////
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Vertex.prototype.determinePredecessors = function (source, options) {
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var graph = this._graph, // Graph
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determined_list = [], // [ID]
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predecessors, // { ID => [ID] }
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source_id = source.getId(), // ID
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todo_list = [source_id], // [ID]
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distances = {}, // { ID => Number }
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current_vertex, // Vertex
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current_vertex_id, // ID
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return_value = false; // { ID => [ID]}
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distances[source_id] = 0;
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if (options.cached) {
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predecessors = graph.getCachedPredecessors(this, source);
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}
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if (!predecessors) {
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predecessors = {};
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while (todo_list.length > 0) {
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current_vertex_id = this._getShortestDistance(todo_list, distances);
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current_vertex = this._graph.getVertex(current_vertex_id);
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if (current_vertex_id === this.getId()) {
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return_value = predecessors;
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break;
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} else {
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removeLastOccurrenceOf(todo_list, current_vertex_id);
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determined_list.push(current_vertex_id);
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todo_list = unite(todo_list, current_vertex._processNeighbors(
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determined_list,
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distances,
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predecessors,
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options
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));
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}
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}
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graph.setCachedPredecessors(this, source, predecessors);
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}
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return return_value;
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};
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////////////////////////////////////////////////////////////////////////////////
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/// @brief Helper function for determinePredecessors (changes distance and predecessors
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///
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/// @FUN{@FA{vertex}._processNeighbors(@FA{determined}, @FA{distances}, @FA{predecessors})}
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///
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////////////////////////////////////////////////////////////////////////////////
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Vertex.prototype._processNeighbors = function (determined_list, distances, predecessors, options) {
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var i,
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current_neighbor_id,
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current_distance,
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raw_neighborlist,
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compared_distance,
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current_weight,
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not_determined_neighbors = [];
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raw_neighborlist = this.getNeighbors(options);
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for (i = 0; i < raw_neighborlist.length; i += 1) {
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current_neighbor_id = raw_neighborlist[i].id;
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if (determined_list.lastIndexOf(current_neighbor_id) === -1) {
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current_weight = raw_neighborlist[i].weight;
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current_distance = distances[this.getId()] + current_weight;
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not_determined_neighbors.push(current_neighbor_id);
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compared_distance = distances[current_neighbor_id];
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if ((compared_distance === undefined) || (compared_distance > current_distance)) {
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predecessors[current_neighbor_id] = [this.getId()];
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distances[current_neighbor_id] = current_distance;
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} else if (compared_distance === current_distance) {
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predecessors[current_neighbor_id].push(this.getId());
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}
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}
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}
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return not_determined_neighbors;
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};
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////////////////////////////////////////////////////////////////////////////////
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/// @brief Get all paths from root to leave vertices for a given tree
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///
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/// @FUN{@FA{vertex}.pathesForTree(@FA{tree}, @FA{path_to_here})}
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///
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////////////////////////////////////////////////////////////////////////////////
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Vertex.prototype.pathesForTree = function (tree, path_to_here) {
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var my_children = tree[this.getId()],
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i,
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my_child,
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pathes = [];
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path_to_here = path_to_here || [];
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path_to_here = path_to_here.concat(this.getId());
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if (my_children === undefined) {
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pathes = [path_to_here.reverse()];
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} else {
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for (i = 0; i < my_children.length; i += 1) {
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my_child = this._graph.getVertex(my_children[i]);
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pathes = pathes.concat(my_child.pathesForTree(tree, path_to_here));
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}
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}
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return pathes;
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};
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////////////////////////////////////////////////////////////////////////////////
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/// @brief Get all neighbours for this vertex
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///
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/// @FUN{@FA{vertex}.getNeighbors(@FA{options})}
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///
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////////////////////////////////////////////////////////////////////////////////
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Vertex.prototype.getNeighbors = function (options) {
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var current_vertex,
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target_array = [],
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addNeighborToList;
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if (! options) {
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options = { };
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}
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var direction = options.direction || 'both',
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labels = options.labels,
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weight = options.weight,
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weight_function = options.weight_function,
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default_weight = options.default_weight || Infinity,
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only = options.only;
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addNeighborToList = function (current_edge, current_vertex) {
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var neighbor_info, current_label = current_edge.getLabel();
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if ((labels === undefined) || (labels.lastIndexOf(current_label) > -1)) {
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neighbor_info = { id: current_vertex.getId() };
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if (weight !== undefined) {
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neighbor_info.weight = current_edge.getProperty(weight) || default_weight;
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} else if (weight_function !== undefined) {
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neighbor_info.weight = weight_function(current_edge);
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} else {
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neighbor_info.weight = 1;
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}
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if ((only === undefined) || (only(current_edge))) {
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target_array.push(neighbor_info);
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}
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}
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};
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if ((direction === 'both') || (direction === 'outbound')) {
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this.getOutEdges().forEach(function (current_edge) {
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current_vertex = current_edge.getInVertex();
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if (current_vertex !== null) {
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addNeighborToList(current_edge, current_vertex);
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}
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});
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}
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if ((direction === 'both') || (direction === 'inbound')) {
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this.getInEdges().forEach(function (current_edge) {
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current_vertex = current_edge.getOutVertex();
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if (current_vertex !== null) {
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addNeighborToList(current_edge, current_vertex);
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}
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});
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}
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return target_array;
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};
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////////////////////////////////////////////////////////////////////////////////
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/// @brief Get the shortest distance for a given list of vertices and
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/// their distances
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///
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/// @FUN{@FA{vertex}._getShortestDistance(@FA{todo_list}, @FA{distances})}
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///
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////////////////////////////////////////////////////////////////////////////////
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Vertex.prototype._getShortestDistance = function (todo_list, distances) {
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var shortest_distance = Infinity,
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vertex = null,
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i,
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distance;
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for (i = 0; i < todo_list.length; i += 1) {
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distance = distances[todo_list[i]];
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if (distance < shortest_distance) {
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shortest_distance = distance;
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vertex = todo_list[i];
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}
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}
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return vertex;
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};
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////////////////////////////////////////////////////////////////////////////////
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/// @brief calculate a measurement
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///
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/// @FUN{@FA{vertex}.measurement(@FA{measurement})}
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///
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/// Calculates the eccentricity, betweenness or closeness of the vertex
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///
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////////////////////////////////////////////////////////////////////////////////
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Vertex.prototype.measurement = function (measurement) {
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var graph = this._graph,
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source = this,
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value;
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if (measurement === "betweenness") {
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value = graph.geodesics({
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grouped: true,
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threshold: true
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}).reduce(function (count, geodesic_group) {
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var included = geodesic_group.filter(function (geodesic) {
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return geodesic.slice(1, -1).indexOf(source.getId()) > -1;
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});
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return (included ? count + (included.length / geodesic_group.length) : count);
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}, 0);
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} else if (measurement === "eccentricity") {
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value = graph._vertices.toArray().reduce(function (calculated, target) {
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var distance = source.distanceTo(graph.getVertex(target._id));
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return Math.max(calculated, distance);
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}, 0);
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} else if (measurement === "closeness") {
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value = graph._vertices.toArray().reduce(function (calculated, target) {
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var distance = source.distanceTo(graph.getVertex(target._id));
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return calculated + distance;
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}, 0);
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} else {
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throw "Unknown Measurement '" + measurement + "'";
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}
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return value;
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};
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////////////////////////////////////////////////////////////////////////////////
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/// @brief return all shortest paths
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///
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/// @FUN{@FA{graph}.geodesics(@FA{options})}
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///
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/// Return all shortest paths
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/// An optional `options` JSON object can be specified to control the result.
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/// `options` can have the following sub-attributes:
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/// - `grouped`: if not specified or set to `false`, the result will be a flat
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/// list. If set to `true`, the result will be a list containing list of
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/// paths, grouped for each combination of source and target.
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/// - `threshold`: if not specified, all paths will be returned. If `threshold`
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/// is `true`, only paths with a minimum length of 3 will be returned
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////////////////////////////////////////////////////////////////////////////////
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Graph.prototype.geodesics = function (options) {
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var sources = this._vertices.toArray(),
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targets = sources.slice(),
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geodesics = [],
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graph = this,
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vertexConstructor;
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options = options || {};
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vertexConstructor = function (raw_vertex) {
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return graph.constructVertex(raw_vertex._id);
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};
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sources = sources.map(vertexConstructor);
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targets = targets.map(vertexConstructor);
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sources.forEach(function (source) {
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targets = targets.slice(1);
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targets.forEach(function (target) {
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var pathes = source.pathTo(target);
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if (pathes.length > 0 && (!options.threshold || pathes[0].length > 2)) {
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if (options.grouped) {
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geodesics.push(pathes);
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} else {
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geodesics = geodesics.concat(pathes);
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}
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}
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});
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});
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return geodesics;
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};
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////////////////////////////////////////////////////////////////////////////////
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/// @brief calculate a measurement
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///
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/// @FUN{@FA{graph}.measurement(@FA{measurement})}
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///
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/// Calculates the diameter or radius of a graph.
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/// `measurement` can either be:
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/// - `diameter`: to calculate the diameter
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/// - `radius`: to calculate the radius
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///
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////////////////////////////////////////////////////////////////////////////////
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Graph.prototype.measurement = function (measurement) {
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var graph = this,
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vertices = graph._vertices.toArray(),
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start_value;
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switch (measurement) {
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case "diameter":
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start_value = 0;
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break;
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case "radius":
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start_value = Infinity;
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break;
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default:
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throw "Unknown Measurement '" + measurement + "'";
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}
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return vertices.reduce(function (calculated, vertex) {
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vertex = graph.getVertex(vertex._id);
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switch (measurement) {
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case "diameter":
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calculated = Math.max(calculated, vertex.measurement("eccentricity"));
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break;
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case "radius":
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calculated = Math.min(calculated, vertex.measurement("eccentricity"));
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break;
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}
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return calculated;
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}, start_value);
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};
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////////////////////////////////////////////////////////////////////////////////
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/// @brief calculate a normalized measurement
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///
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/// @FUN{@FA{graph}.normalizedMeasurement(@FA{measurement})}
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///
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/// Calculates the normalized degree, closeness, betweenness or eccentricity
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/// of all vertices in a graph
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/// `measurement` can either be:
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/// - `closeness`: to calculate the closeness
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/// - `betweenness`: to calculate the betweenness
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/// - `eccentricity`: to calculate the eccentricity
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///
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////////////////////////////////////////////////////////////////////////////////
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Graph.prototype.normalizedMeasurement = function (measurement) {
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var graph = this,
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vertices = graph._vertices.toArray(),
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vertex_map,
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max = 0;
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vertex_map = vertices.reduce(function (map, raw_vertex) {
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var vertex = graph.constructVertex(raw_vertex._id),
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measured;
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switch(measurement) {
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case "closeness":
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measured = 1 / vertex.measurement("closeness");
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break;
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case "betweenness":
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measured = vertex.measurement("betweenness");
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break;
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case "eccentricity":
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measured = 1 / vertex.measurement("eccentricity");
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break;
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default:
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throw "Unknown measurement";
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}
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if (measured > max) {
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max = measured;
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}
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map[vertex.getId()] = measured;
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return map;
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}, {});
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Object.keys(vertex_map).forEach(function(key) {
|
|
vertex_map[key] = vertex_map[key] / max;
|
|
});
|
|
|
|
return vertex_map;
|
|
};
|
|
|
|
|