Package com.jgalgo.graph

Graphs object are the fundamental building blocks of the JGAlgo library.

A graph is a collection of vertices (nodes) and edges (links) between them. The edges may be directed or undirected. The Graph object represent a graph, in which vertices and edges are hashable identifiers. Vertices can be added or removed to/from a graph, and edges can be added or removed between vertices. The Graph object also provides methods to query the graph, such as the number of vertices and edges, and whether a vertex is connected to another vertex, the out-edges or in-edges of a vertex, etc.

Weights can be associated with the vertices or edges of a graph, and the Graph object provides methods to add or remove weights to it. When a weight is added to the vertices, it is added to all vertices of the graph. The weights can be an Object or any other primitive such as int, double, etc. When weights are added to a graph via the Graph.addVerticesWeights(String, Class) or Graph.addEdgesWeights(String, Class) methods, a Weights object is created and return, which allow setting and getting the weights values by vertex/edge identifier. If the weights type is primitive, a specific subclass of Weights such as WeightsInt, WeightsDouble, etc. is returned. These specific primitive weights containers avoid the overhead of boxing and unboxing primitive values.

Each Graph object expose an IndexGraph via the Graph.indexGraph() method. An index graph is a graph in which the identifiers of the vertices are always in the range [0, n), where n is the number of vertices in the graph, and the identifiers of the edges are always in the range [0, m), where m is the number of edges in the graph. Index graphs are much more efficient than regular graphs, as simple arrays are enough to store the data (internal and additional weights) associated with the vertices/edges. When a vertex or edge is removed from an index graph, some identifiers may change, as it must maintain the invariant that the identifiers are always in the range [0, n) and [0, m). This makes the index graph less convenient to use, but much more efficient. The default graph implementation uses an index graph internally, and expose it via the Graph.indexGraph() method. Good written algorithms should accept a regular graph, retrieve its index graph, perform the heavy computation on the index graph, and translate back the result to the regular graph identifiers. Index graphs should rarely be used directly by a user.

Interface Summary

Interface	Description
EdgeIter<V,E>	Iterator used to iterate over graph edges.
EdgeSet<V,E>	Set of graph edges.
Graph<V,E>	A discrete graph with vertices and edges.
GraphBuilder<V,E>	A builder for graphs.
GraphFactory<V,E>	A factory for Graph objects.
IdBuilder<K>	Builder for unique identifiers of vertices or edges in a graph.
IdBuilderInt	Builder for unique identifiers of vertices or edges in an IntGraph.
IEdgeIter	Iterator used to iterate over int graph edges.
IEdgeSet	Set of int graph edges.
IndexGraph	A graph whose vertices and edges identifiers are indices.
IndexGraphBuilder	A builder for Index graphs.
IndexGraphBuilder.ReIndexedGraph	A result object of re-indexing and building a graph operation.
IndexGraphBuilder.ReIndexingMap	A map of indices, mapping an original index to a re-indexed index.
IndexGraphFactory	A factory for Index graphs.
IndexIdMap<K>	A mapping between Graph IDs to IndexGraph indices.
IndexIntIdMap	A mapping between IntGraph IDs to IndexGraph indices.
IndexRemoveListener	A listener that will be notified when an IndexGraph remove a vertex or an edge.
IntGraph	A discrete graph with int vertices and edges.
IntGraphBuilder	A builder for int graphs.
IntGraphFactory	A factory for IntGraph objects.
IWeightFunction	Weight function that maps graph edges or vertices of IntGraph to weights.
IWeightFunctionInt	Weight function that maps graph edges or vertices of IntGraph to integer weights.
IWeights<T>	Weights of int graph vertices or edges.
IWeightsBool	Specific weights of boolean for int graphs.
IWeightsByte	Specific weights of byte for int graphs.
IWeightsChar	Specific weights of char for int graphs.
IWeightsDouble	Specific weights of double for int graphs.
IWeightsFloat	Specific weights of float for int graphs.
IWeightsInt	Specific weights of int for int graphs.
IWeightsLong	Specific weights of long for int graphs.
IWeightsObj<T>	Specific weights of Object for int graphs.
IWeightsShort	Specific weights of short for int graphs.
WeightFunction<K>	Weight function that maps graph edges or vertices to weights.
WeightFunctionInt<K>	Weight function that maps graph edges or vertices to integer weights.
Weights<K,T>	Weights of graph vertices or edges.
WeightsBool<K>	Specific weights of boolean.
WeightsByte<K>	Specific weights of byte.
WeightsChar<K>	Specific weights of char.
WeightsDouble<K>	Specific weights of double.
WeightsFloat<K>	Specific weights of float.
WeightsInt<K>	Specific weights of int.
WeightsLong<K>	Specific weights of long.
WeightsObj<K,T>	Specific weights of Object.
WeightsShort<K>	Specific weights of short.

Class Summary

Class	Description
AbstractGraph<V,E>	Abstract implementation of Graph.
Graphs	Static methods class for graphs.
IndexIdMaps	Static methods class for index-id maps.
WeightFunctions	Static methods class for weight functions.

Enum Summary

Enum	Description
GraphFactory.Hint	Hints for a graph factory.

Exception Summary

Exception	Description
NoSuchEdgeException	Exception thrown when an edge is not found in a graph.
NoSuchVertexException	Exception thrown when a vertex is not found in a graph.