Package smile.graph

# Interface Graph

All Known Implementing Classes:
`AdjacencyList`, `AdjacencyMatrix`

public interface Graph
A graph is an abstract representation of a set of objects where some pairs of the objects are connected by links. The interconnected objects are represented by mathematical abstractions called vertices, and the links that connect some pairs of vertices are called edges. The edges may be directed (asymmetric) or undirected (symmetric). A graph is a weighted graph if a number (weight) is assigned to each edge. Such weights might represent, for example, costs, lengths or capacities, etc. depending on the problem.
• ## Nested Class Summary

Nested Classes
Modifier and Type
Interface
Description
`static class `
`Graph.Edge`
Graph edge.
• ## Method Summary

Modifier and Type
Method
Description
`void`
```addEdge(int source, int target)```
Creates a new edge in this graph, going from the source vertex to the target vertex, and returns the created edge.
`void`
```addEdge(int source, int target, double weight)```
Creates a new edge in this graph, going from the source vertex to the target vertex, and returns the created edge.
`int[][]`
`bfs()`
Breadth-first search connected components of graph.
`void`
`bfs(Visitor vistor)`
BFS search on graph and performs some operation defined in visitor on each vertex during traveling.
`int[][]`
`dfs()`
Depth-first search connected components of graph.
`void`
`dfs(Visitor vistor)`
DFS search on graph and performs some operation defined in visitor on each vertex during traveling.
`default double[][]`
`dijkstra()`
Calculates the all pair shortest path by Dijkstra algorithm.
`double[]`
`dijkstra(int s)`
Calculate the shortest path from a source to all other vertices in the graph by Dijkstra algorithm.
`int`
`getDegree(int vertex)`
Returns the degree of the specified vertex.
`Graph.Edge`
```getEdge(int source, int target)```
Returns an edge connecting source vertex to target vertex if such edge exist in this graph.
`Collection<Graph.Edge>`
`getEdges()`
Returns the edges in this graph.
`Collection<Graph.Edge>`
`getEdges(int vertex)`
Returns the edges from the specified vertex.
`Collection<Graph.Edge>`
```getEdges(int source, int target)```
Returns the edges connecting source vertex to target vertex if such vertices exist in this graph.
`int`
`getIndegree(int vertex)`
Returns the in-degree of the specified vertex.
`int`
`getNumVertices()`
Returns the number of vertices.
`int`
`getOutdegree(int vertex)`
Returns the out-degree of the specified vertex.
`double`
```getWeight(int source, int target)```
Returns the weight assigned to a given edge.
`boolean`
```hasEdge(int source, int target)```
Returns true if and only if this graph contains an edge going from the source vertex to the target vertex.
`void`
```removeEdge(int source, int target)```
In a simple graph, removes and returns the edge going from the specified source vertex to the specified target vertex.
`void`
`removeEdge(Graph.Edge edge)`
Removes the specified edge from the graph.
`void`
`removeEdges(Collection<Graph.Edge> edges)`
Removes a set of edges from the graph.
`Graph`
```setWeight(int source, int target, double weight)```
Sets the weight assigned to a given edge.
`int[]`
`sortbfs()`
Topological sort digraph by breadth-first search of graph.
`int[]`
`sortdfs()`
Reverse topological sort digraph by depth-first search of graph.
`Graph`
`subgraph(int[] vertices)`
Returns a subgraph containing all given vertices.
`IMatrix`
`toMatrix()`
Returns the (dense or sparse) matrix representation of the graph.
• ## Method Details

• ### getNumVertices

int getNumVertices()
Returns the number of vertices.
Returns:
the number of vertices.
• ### hasEdge

boolean hasEdge(int source, int target)
Returns true if and only if this graph contains an edge going from the source vertex to the target vertex. In undirected graphs the same result is obtained when source and target are inverted.
Parameters:
`source` - the id of source vertex of the edge.
`target` - the id of target vertex of the edge.
Returns:
true if this graph contains the specified edge.
• ### getWeight

double getWeight(int source, int target)
Returns the weight assigned to a given edge. Unweighted graphs always return 1.0. For multi-graph, the return value is ill-defined.
Parameters:
`source` - the id of source vertex of the edge.
`target` - the id of target vertex of the edge.
Returns:
the edge weight
• ### setWeight

Graph setWeight(int source, int target, double weight)
Sets the weight assigned to a given edge. For multi-graph, the operation is ill-defined.
Parameters:
`source` - the id of source vertex of the edge.
`target` - the id of target vertex of the edge.
`weight` - the edge weight
Returns:
this graph.
• ### getEdges

getEdges()
Returns the edges in this graph.
Returns:
the edges.
• ### getEdges

getEdges(int vertex)
Returns the edges from the specified vertex. If no edges are touching the specified vertex returns an empty set.
Parameters:
`vertex` - the id of vertex for which a set of touching edges is to be returned.
Returns:
the edges touching the specified vertex.
• ### getEdges

getEdges(int source, int target)
Returns the edges connecting source vertex to target vertex if such vertices exist in this graph. If both vertices exist but no edges found, returns an empty set.

In undirected graphs, some of the returned edges may have their source and target vertices in the opposite order.

Parameters:
`source` - the id of source vertex of the edge.
`target` - the id of target vertex of the edge.
Returns:
the edges connecting source vertex to target vertex.
• ### getEdge

Graph.Edge getEdge(int source, int target)
Returns an edge connecting source vertex to target vertex if such edge exist in this graph. Otherwise, returns ` null`.

In undirected graphs, the returned edge may have its source and target vertices in the opposite order.

For multi-graph, the return value is ill-defined.

Parameters:
`source` - the id of source vertex of the edge.
`target` - the id of target vertex of the edge.
Returns:
an edge connecting source vertex to target vertex if there are connected. Otherwise, null.

Creates a new edge in this graph, going from the source vertex to the target vertex, and returns the created edge.
Parameters:
`source` - the id of source vertex of the edge.
`target` - the id of target vertex of the edge.

void addEdge(int source, int target, double weight)
Creates a new edge in this graph, going from the source vertex to the target vertex, and returns the created edge.
Parameters:
`source` - the id of source vertex of the edge.
`target` - the id of target vertex of the edge.
`weight` - the weight of edge.
• ### removeEdges

void removeEdges(Collection<Graph.Edge> edges)
Removes a set of edges from the graph.
Parameters:
`edges` - edges to be removed from this graph.
• ### removeEdge

void removeEdge(int source, int target)
In a simple graph, removes and returns the edge going from the specified source vertex to the specified target vertex.
Parameters:
`source` - the id of source vertex of the edge.
`target` - the id of target vertex of the edge.
• ### removeEdge

void removeEdge(Graph.Edge edge)
Removes the specified edge from the graph. Returns true if the graph contained the specified edge.
Parameters:
`edge` - edge to be removed from this graph, if present.
• ### getDegree

int getDegree(int vertex)
Returns the degree of the specified vertex. A degree of a vertex in an undirected graph is the number of edges touching that vertex.
Parameters:
`vertex` - the id of vertex.
Returns:
the degree of the specified vertex.
• ### getIndegree

int getIndegree(int vertex)
Returns the in-degree of the specified vertex. An in-degree of a vertex in a directed graph is the number of edges head to that vertex.
Parameters:
`vertex` - the id of vertex.
Returns:
the degree of the specified vertex.
• ### getOutdegree

int getOutdegree(int vertex)
Returns the out-degree of the specified vertex. An out-degree of a vertex in a directed graph is the number of edges from that vertex.
Parameters:
`vertex` - the id of vertex.
Returns:
the degree of the specified vertex.
• ### sortdfs

int[] sortdfs()
Reverse topological sort digraph by depth-first search of graph.
Returns:
an array of vertex IDs in the reverse topological order.
• ### dfs

int[][] dfs()
Depth-first search connected components of graph.
Returns:
a two-dimensional array of which each row is the vertices in the same connected component.
• ### dfs

void dfs(Visitor vistor)
DFS search on graph and performs some operation defined in visitor on each vertex during traveling.
Parameters:
`vistor` - the visitor functor.
• ### sortbfs

int[] sortbfs()
Topological sort digraph by breadth-first search of graph.
Returns:
an array of vertex IDs in the topological order.
• ### bfs

int[][] bfs()
Breadth-first search connected components of graph.
Returns:
a two-dimensional array of which each row is the vertices in the same connected component.
• ### bfs

void bfs(Visitor vistor)
BFS search on graph and performs some operation defined in visitor on each vertex during traveling.
Parameters:
`vistor` - the visitor functor.
• ### subgraph

Graph subgraph(int[] vertices)
Returns a subgraph containing all given vertices.
Parameters:
`vertices` - the vertices to be included in subgraph.
Returns:
a subgraph containing all given vertices
• ### dijkstra

double[] dijkstra(int s)
Calculate the shortest path from a source to all other vertices in the graph by Dijkstra algorithm.
Parameters:
`s` - the source vertex.
Returns:
the length of shortest path to other vertices.
• ### dijkstra

default double[][] dijkstra()
Calculates the all pair shortest path by Dijkstra algorithm.
Returns:
the length of shortest path between vertices.
• ### toMatrix

IMatrix toMatrix()
Returns the (dense or sparse) matrix representation of the graph.
Returns:
the matrix representation of the graph.