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Update Graph.js
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raidenkhan
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// Define a class called "Graph."
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export default class Graph {
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/**
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* @param {boolean} isDirected
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* Constructor for the Graph class.
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* @param {boolean} isDirected - Specifies whether the graph is directed (default is undirected).
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*/
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constructor(isDirected = false) {
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// Initialize empty objects to store vertices and edges.
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this.vertices = {};
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this.edges = {};
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// Store whether the graph is directed or not.
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this.isDirected = isDirected;
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}
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/**
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* @param {GraphVertex} newVertex
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* @returns {Graph}
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* Add a new vertex to the graph.
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* @param {GraphVertex} newVertex - The vertex to be added.
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* @returns {Graph} - Returns the graph to allow method chaining.
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*/
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addVertex(newVertex) {
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// Add the vertex to the vertices object using its key.
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this.vertices[newVertex.getKey()] = newVertex;
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return this;
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return this; // Return the graph.
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}
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/**
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* @param {string} vertexKey
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* @returns GraphVertex
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* Get a vertex by its key.
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* @param {string} vertexKey - The key of the vertex to retrieve.
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* @returns GraphVertex - The vertex with the specified key.
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*/
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getVertexByKey(vertexKey) {
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return this.vertices[vertexKey];
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}
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/**
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* @param {GraphVertex} vertex
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* @returns {GraphVertex[]}
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*/
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getNeighbors(vertex) {
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return vertex.getNeighbors();
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}
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// Other methods follow the same pattern of documenting their purpose and parameters.
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// I'll provide a brief summary of each below:
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/**
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* @return {GraphVertex[]}
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* Get neighbors of a given vertex.
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* @param {GraphVertex} vertex - The vertex to find neighbors for.
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* @returns {GraphVertex[]} - An array of neighboring vertices.
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*/
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getAllVertices() {
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return Object.values(this.vertices);
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}
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/**
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* @return {GraphEdge[]}
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* Get all vertices in the graph.
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* @returns {GraphVertex[]} - An array of all vertices in the graph.
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*/
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getAllEdges() {
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return Object.values(this.edges);
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}
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/**
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* @param {GraphEdge} edge
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* @returns {Graph}
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* Get all edges in the graph.
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* @returns {GraphEdge[]} - An array of all edges in the graph.
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*/
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addEdge(edge) {
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// Try to find and end start vertices.
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let startVertex = this.getVertexByKey(edge.startVertex.getKey());
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let endVertex = this.getVertexByKey(edge.endVertex.getKey());
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// Insert start vertex if it wasn't inserted.
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if (!startVertex) {
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this.addVertex(edge.startVertex);
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startVertex = this.getVertexByKey(edge.startVertex.getKey());
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}
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// Insert end vertex if it wasn't inserted.
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if (!endVertex) {
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this.addVertex(edge.endVertex);
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endVertex = this.getVertexByKey(edge.endVertex.getKey());
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}
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// Check if edge has been already added.
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if (this.edges[edge.getKey()]) {
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throw new Error('Edge has already been added before');
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} else {
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this.edges[edge.getKey()] = edge;
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}
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// Add edge to the vertices.
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if (this.isDirected) {
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// If graph IS directed then add the edge only to start vertex.
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startVertex.addEdge(edge);
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} else {
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// If graph ISN'T directed then add the edge to both vertices.
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startVertex.addEdge(edge);
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endVertex.addEdge(edge);
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}
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return this;
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}
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/**
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* @param {GraphEdge} edge
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* Add an edge to the graph between two vertices.
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* @param {GraphEdge} edge - The edge to add.
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* @returns {Graph} - Returns the graph to allow method chaining.
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*/
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deleteEdge(edge) {
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// Delete edge from the list of edges.
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if (this.edges[edge.getKey()]) {
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delete this.edges[edge.getKey()];
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} else {
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throw new Error('Edge not found in graph');
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}
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// Try to find and end start vertices and delete edge from them.
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const startVertex = this.getVertexByKey(edge.startVertex.getKey());
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const endVertex = this.getVertexByKey(edge.endVertex.getKey());
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startVertex.deleteEdge(edge);
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endVertex.deleteEdge(edge);
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}
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/**
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* @param {GraphVertex} startVertex
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* @param {GraphVertex} endVertex
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* @return {(GraphEdge|null)}
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* Delete an edge from the graph.
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* @param {GraphEdge} edge - The edge to delete.
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*/
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findEdge(startVertex, endVertex) {
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const vertex = this.getVertexByKey(startVertex.getKey());
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if (!vertex) {
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return null;
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}
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return vertex.findEdge(endVertex);
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}
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/**
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* @return {number}
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* Find an edge between two vertices.
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* @param {GraphVertex} startVertex - The starting vertex.
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* @param {GraphVertex} endVertex - The ending vertex.
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* @returns {GraphEdge|null} - The found edge or null if not found.
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*/
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getWeight() {
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return this.getAllEdges().reduce((weight, graphEdge) => {
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return weight + graphEdge.weight;
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}, 0);
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}
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/**
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* Reverse all the edges in directed graph.
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* @return {Graph}
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* Get the total weight of all edges in the graph.
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* @returns {number} - The total weight of all edges.
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*/
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reverse() {
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/** @param {GraphEdge} edge */
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this.getAllEdges().forEach((edge) => {
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// Delete straight edge from graph and from vertices.
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this.deleteEdge(edge);
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// Reverse the edge.
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edge.reverse();
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// Add reversed edge back to the graph and its vertices.
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this.addEdge(edge);
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});
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return this;
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}
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/**
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* @return {object}
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* Reverse all edges in a directed graph.
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* @returns {Graph} - Returns the graph with reversed edges.
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*/
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getVerticesIndices() {
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const verticesIndices = {};
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this.getAllVertices().forEach((vertex, index) => {
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verticesIndices[vertex.getKey()] = index;
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});
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return verticesIndices;
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}
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/**
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* @return {*[][]}
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* Get an object mapping vertex keys to their indices.
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* @returns {object} - An object with vertex keys as keys and their indices as values.
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*/
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getAdjacencyMatrix() {
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const vertices = this.getAllVertices();
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const verticesIndices = this.getVerticesIndices();
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// Init matrix with infinities meaning that there is no ways of
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// getting from one vertex to another yet.
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const adjacencyMatrix = Array(vertices.length).fill(null).map(() => {
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return Array(vertices.length).fill(Infinity);
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});
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// Fill the columns.
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vertices.forEach((vertex, vertexIndex) => {
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vertex.getNeighbors().forEach((neighbor) => {
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const neighborIndex = verticesIndices[neighbor.getKey()];
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adjacencyMatrix[vertexIndex][neighborIndex] = this.findEdge(vertex, neighbor).weight;
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});
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});
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return adjacencyMatrix;
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}
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/**
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* @return {string}
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* Get the adjacency matrix of the graph.
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* @returns {*[][]} - A 2D array representing the adjacency matrix.
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*/
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/**
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* Convert the graph to a string representation.
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* @returns {string} - A string representing the graph's vertices.
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*/
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toString() {
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return Object.keys(this.vertices).toString();
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}
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}
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