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/*
 * (C) Copyright 2016-2023, by Dimitrios Michail and Contributors.
 *
 * JGraphT : a free Java graph-theory library
 *
 * See the CONTRIBUTORS.md file distributed with this work for additional
 * information regarding copyright ownership.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License 2.0 which is available at
 * http://www.eclipse.org/legal/epl-2.0, or the
 * GNU Lesser General Public License v2.1 or later
 * which is available at
 * http://www.gnu.org/licenses/old-licenses/lgpl-2.1-standalone.html.
 *
 * SPDX-License-Identifier: EPL-2.0 OR LGPL-2.1-or-later
 */
package org.jgrapht.nio.csv;

import org.jgrapht.*;
import org.jgrapht.alg.util.*;
import org.jgrapht.nio.*;

import java.io.*;
import java.util.*;
import java.util.function.*;

/**
 * Imports a graph from a CSV Format or any other Delimiter-separated value format.
 * 
 * 

* The importer supports various different formats which can be adjusted using the * {@link #setFormat(CSVFormat) setFormat} method. The supported formats are the same CSV formats * used by Gephi . For some * of the formats, the behavior of the importer can be adjusted using the * {@link #setParameter(org.jgrapht.nio.csv.CSVFormat.Parameter, boolean) setParameter} method. See * {@link CSVFormat} for a description of the formats. *

* *

* The importer respects rfc4180. The caller can * also adjust the separator to something like semicolon or pipe instead of comma. In such a case, * all fields are unescaped using the new separator. See * Delimiter- separated * values for more information. *

* *

* This importer does not distinguish between {@link CSVFormat#EDGE_LIST} and * {@link CSVFormat#ADJACENCY_LIST}. In both cases it assumes the format is * {@link CSVFormat#ADJACENCY_LIST}. *

* *

* The graph vertices and edges are build using the corresponding graph suppliers. The id of the * vertices in the original file are reported as a vertex attribute named "ID". * *

* The default behavior of the importer is to use the graph vertex supplier in order to create * vertices. The user can also bypass vertex creation by providing a custom vertex factory method * using {@link #setVertexFactory(Function)}. The factory method is responsible to create a new * graph vertex given the vertex identifier read from file. * * @see CSVFormat * * @param the graph vertex type * @param the graph edge type * * @author Dimitrios Michail */ public class CSVImporter extends BaseEventDrivenImporter implements GraphImporter { private static final char DEFAULT_DELIMITER = ','; private static final String DEFAULT_VERTEX_ID_KEY = "ID"; private static final String DEFAULT_WEIGHT_KEY = "weight"; private CSVFormat format; private char delimiter; private final Set parameters; private Function vertexFactory; /** * Constructs a new importer using the {@link CSVFormat#ADJACENCY_LIST} format as default. */ public CSVImporter() { this(CSVFormat.ADJACENCY_LIST, DEFAULT_DELIMITER); } /** * Constructs a new importer. * * @param format format to use out of the supported ones */ public CSVImporter(CSVFormat format) { this(format, DEFAULT_DELIMITER); } /** * Constructs a new importer. * * @param format format to use out of the supported ones * @param delimiter delimiter to use (comma, semicolon, pipe, etc.) */ public CSVImporter(CSVFormat format, char delimiter) { super(); this.format = format; if (!DSVUtils.isValidDelimiter(delimiter)) { throw new IllegalArgumentException("Character cannot be used as a delimiter"); } this.delimiter = delimiter; this.parameters = new HashSet<>(); } /** * Get the format that the importer is using. * * @return the input format */ public CSVFormat getFormat() { return format; } /** * Set the format of the importer * * @param format the format to use */ public void setFormat(CSVFormat format) { this.format = format; } /** * Get the delimiter (comma, semicolon, pipe, etc). * * @return the delimiter */ public char getDelimiter() { return delimiter; } /** * Set the delimiter (comma, semicolon, pipe, etc). * * @param delimiter the delimiter to use */ public void setDelimiter(char delimiter) { if (!DSVUtils.isValidDelimiter(delimiter)) { throw new IllegalArgumentException("Character cannot be used as a delimiter"); } this.delimiter = delimiter; } /** * Return if a particular parameter of the exporter is enabled * * @param p the parameter * @return {@code true} if the parameter is set, {@code false} otherwise */ public boolean isParameter(CSVFormat.Parameter p) { return parameters.contains(p); } /** * Set the value of a parameter of the exporter * * @param p the parameter * @param value the value to set */ public void setParameter(CSVFormat.Parameter p, boolean value) { if (value) { parameters.add(p); } else { parameters.remove(p); } } /** * Get the user custom vertex factory. This is null by default and the graph supplier is used * instead. * * @return the user custom vertex factory */ public Function getVertexFactory() { return vertexFactory; } /** * Set the user custom vertex factory. The default behavior is being null in which case the * graph vertex supplier is used. * * If supplied the vertex factory is called every time a new vertex is encountered in the file. * The method is called with parameter the vertex identifier from the file and should return the * actual graph vertex to add to the graph. * * @param vertexFactory a vertex factory */ public void setVertexFactory(Function vertexFactory) { this.vertexFactory = vertexFactory; } /** * Import a graph. * *

* The provided graph must be able to support the features of the graph that is read. For * example if the input contains self-loops then the graph provided must also support * self-loops. The same for multiple edges. * *

* If the provided graph is a weighted graph, the importer also reads edge weights. * * @param graph the graph * @param input the input reader * @throws ImportException in case an error occurs, such as I/O or parse error */ @Override public void importGraph(Graph graph, Reader input) throws ImportException { CSVEventDrivenImporter genericImporter = new CSVEventDrivenImporter(); genericImporter.setDelimiter(delimiter); genericImporter.setFormat(format); genericImporter.setParameter( CSVFormat.Parameter.EDGE_WEIGHTS, isParameter(CSVFormat.Parameter.EDGE_WEIGHTS)); genericImporter.setParameter( CSVFormat.Parameter.MATRIX_FORMAT_NODEID, isParameter(CSVFormat.Parameter.MATRIX_FORMAT_NODEID)); genericImporter.setParameter( CSVFormat.Parameter.MATRIX_FORMAT_ZERO_WHEN_NO_EDGE, isParameter(CSVFormat.Parameter.MATRIX_FORMAT_ZERO_WHEN_NO_EDGE)); Consumers consumers = new Consumers(graph); genericImporter.addVertexConsumer(consumers.vertexConsumer); genericImporter.addEdgeConsumer(consumers.edgeConsumer); genericImporter.importInput(input); } private class Consumers { private Graph graph; private GraphType graphType; private Map map; public Consumers(Graph graph) { this.graph = graph; this.graphType = graph.getType(); this.map = new HashMap<>(); } public final Consumer vertexConsumer = (t) -> { if (map.containsKey(t)) { throw new ImportException("Node " + t + " already exists"); } V v; if (vertexFactory != null) { v = vertexFactory.apply(t); graph.addVertex(v); } else { v = graph.addVertex(); } map.put(t, v); notifyVertex(v); notifyVertexAttribute(v, DEFAULT_VERTEX_ID_KEY, DefaultAttribute.createAttribute(t)); }; public final Consumer> edgeConsumer = (t) -> { String source = t.getFirst(); V from = map.get(t.getFirst()); if (from == null) { throw new ImportException("Node " + source + " does not exist"); } String target = t.getSecond(); V to = map.get(target); if (to == null) { throw new ImportException("Node " + target + " does not exist"); } E e = graph.addEdge(from, to); if (graphType.isWeighted() && t.getThird() != null) { graph.setEdgeWeight(e, t.getThird()); } notifyEdge(e); if (graphType.isWeighted() && t.getThird() != null) { notifyEdgeAttribute( e, DEFAULT_WEIGHT_KEY, DefaultAttribute.createAttribute(t.getThird())); } }; } }





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