Module org.jgrapht.opt
Package org.jgrapht.opt.graph.sparse

Class SparseIntDirectedGraph

  • All Implemented Interfaces:
    Graph<Integer,​Integer>
    Direct Known Subclasses:
    SparseIntDirectedWeightedGraph
    public class SparseIntDirectedGraph
extends org.jgrapht.opt.graph.sparse.specifics.AbstractSparseSpecificsGraph<org.jgrapht.opt.graph.sparse.specifics.SparseGraphSpecifics>
    A sparse directed graph.

    Assuming the graph has $n$ vertices, the vertices are numbered from $0$ to $n-1$. Similarly, edges are numbered from $0$ to $m-1$ where $m$ is the total number of edges.

    It stores two boolean incidence matrix of the graph (rows are vertices and columns are edges) as Compressed Sparse Rows (CSR). Constant time source and target lookups are provided by storing the edge lists in arrays. This is a classic format for write-once read-many use cases. Thus, the graph is unmodifiable.

    The question of whether a sparse or dense representation is more appropriate is highly dependent on various factors such as the graph, the machine running the algorithm and the algorithm itself. Wilkinson defined a matrix as "sparse" if it has enough zeros that it pays to take advantage of them. For more details see

    • Wilkinson, J. H. 1971. Linear algebra; part II: the algebraic eigenvalue problem. In Handbook for Automatic Computation, J. H. Wilkinson and C. Reinsch, Eds. Vol. 2. Springer-Verlag, Berlin, New York.
    Additional information about sparse representations can be found in the wikipedia.
    Author:
    Dimitrios Michail

    • Constructor Detail

      • SparseIntDirectedGraph

        public SparseIntDirectedGraph​(int numVertices,
                              List<Pair<Integer,​Integer>> edges)
        Create a new graph from an edge list.
        Parameters:
        numVertices - the number of vertices
        edges - the edge list

      • SparseIntDirectedGraph

        public SparseIntDirectedGraph​(int numVertices,
                              List<Pair<Integer,​Integer>> edges,
                              IncomingEdgesSupport incomingEdgesSupport)
        Create a new graph from an edge list.
        Parameters:
        numVertices - the number of vertices
        edges - the edge list
        incomingEdgesSupport - whether to support incoming edges or not

      • SparseIntDirectedGraph

        public SparseIntDirectedGraph​(int numVertices,
                              int numEdges,
                              Supplier<Stream<Pair<Integer,​Integer>>> edges,
                              IncomingEdgesSupport incomingEdgesSupport)
        Create a new graph from an edge stream.
        Parameters:
        numVertices - the number of vertices
        numEdges - the number of edges
        edges - the edge stream
        incomingEdgesSupport - whether to support incoming edges or not