org.jgrapht.nio.csv.CSVFormat Maven / Gradle / Ivy
/*
* (C) Copyright 2016-2021, 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;
/**
* Supported CSV formats.
*
*
* -
*
* Format {@link #EDGE_LIST} contains one edge per line. The following example
*
*
* a,b
* b,c
*
*
* represents a graph with two edges: a->b and b->c.
*
* -
*
* Format {@link #ADJACENCY_LIST} contains the adjacency list of each vertex per line. The first
* field on a line is a vertex while the remaining fields are its neighbors.
*
*
* a,b
* b,c,d
* c,a,c,d
*
*
* represents a graph with edges: a->b, b->c, b->d, c->a, c->c, c->d.
*
*
* Mixed variants of {@link #EDGE_LIST} and {@link #ADJACENCY_LIST} are also considered valid. As an
* example consider the following input
*
*
* a,b
* b,a
* d,a
* c,a,b
* b,d,a
*
*
* which represents a graph with edges: a->b, b->a, d->a, c->a, c->b, b->d,
* b->a. Multiple occurrences of the same edge result into a multi-graph.
*
*
* Weighted variants are also valid if {@link CSVFormat.Parameter#EDGE_WEIGHTS} is set. In this case
* the target vertex must be followed by the edge weight. The following example illustrates the
* weighted variant:
*
*
* a,b,2.0
* b,a,3.0
* d,a,2.0
* c,a,1.5,b,2.5
* b,d,3.3,a,5.5
*
*
*
* -
*
* Format {@link #MATRIX} outputs an adjacency matrix representation of the graph. Each line
* represents a vertex.
*
* The following
*
*
* 0,1,0,1,0
* 1,0,0,0,0
* 0,0,1,0,0
* 0,1,0,1,0
* 0,0,0,0,0
*
*
* represents a graph with five vertices 1,2,3,4,5 which contains edges: 1->2, 1->4, 2->1,
* 3->3, 4->2, 4->4.
*
*
* In case {@link CSVFormat.Parameter#MATRIX_FORMAT_ZERO_WHEN_NO_EDGE} is not set the equivalent
* format would be:
*
*
* ,1,,1,
* 1,,,,
* ,,1,,
* ,1,,1,
* ,,,,
*
*
*
* Weighted variants are also valid if {@link CSVFormat.Parameter#EDGE_WEIGHTS} is set. The above
* example would then be:
*
*
* ,1.0,,1.0,
* 1.0,,,,
* ,,1.0,,
* ,1.0,,1.0,
* ,,,,
*
*
* If additionally {@link CSVFormat.Parameter#MATRIX_FORMAT_ZERO_WHEN_NO_EDGE} is set then a zero as
* an integer means that the corresponding edge is missing, while a zero as a double means than the
* edge exists and has zero weight.
*
*
* If parameter {@link CSVFormat.Parameter#MATRIX_FORMAT_NODEID} is set then node identifiers are
* also included as in the following example:
*
*
* ,a,b,c,d,e
* a,,1,,1,
* b,1,,,,
* c,,,1,,
* d,,1,,1,
* e,,,,,
*
*
* In the above example the first line contains the node identifiers and the first field of each
* line contain the vertex it corresponds to. In case node identifiers are present line-shuffled
* input is also valid such as:
*
*
* ,a,b,c,d,e
* c,,,1,,
* b,1,,,,
* e,,,,,
* d,,1,,1,
* a,,1,,1,
*
*
* The last example represents the graph with edges: a->b, a->d, b->a, c->c, d->b,
* d->d.
*
*
*
*
* @author Dimitrios Michail
*
*/
public enum CSVFormat
{
/**
* Edge list
*/
EDGE_LIST,
/**
* Adjacency list
*/
ADJACENCY_LIST,
/**
* Matrix
*/
MATRIX;
/**
* Parameters that affect the behavior of CVS importers/exporters.
*/
public enum Parameter
{
/**
* Whether to import/export edge weights.
*/
EDGE_WEIGHTS,
/**
* Whether to import/export node ids. Only valid for the {@link CSVFormat#MATRIX MATRIX}
* format.
*/
MATRIX_FORMAT_NODEID,
/**
* Whether the input/output contains zero for missing edges. Only valid for the
* {@link CSVFormat#MATRIX MATRIX} format.
*/
MATRIX_FORMAT_ZERO_WHEN_NO_EDGE,
}
}