addEdge {graph} | R Documentation

## addEdge

### Description

A function to add an edge to a graph.

### Usage

    addEdge(from, to, graph, weights)

### Arguments

`from` | The node the edge starts at
`to` | The node the edge goes to.
`graph` | The graph that the edge is being added to.
`weights` | A vector of weights, one for each edge.

### Details

Both `from` and `to` can be vectors. They need not be the same length (if not the standard rules for replicating the shorter one are used). Edges are added to the graph between the supplied nodes.

The `weights` are given for each edge.

The implementation is a bit too oriented towards the `graphNEL` class and will likely change in the next release to accomodate more general graph classes.

If the graph is undirected then the edge is bidirectional (and only needs to be added once). For directed graphs the edge is directional.

### Value

A new instance of a graph object with the same class as `graph` but with the indicated edges added.

### Author(s)

R. Gentleman

### See Also

`addNode`,`removeEdge`, `removeNode`

### Examples

    V <- LETTERS[1:4]
    edL2 <- vector("list", length=4)
    names(edL2) <- V
    for(i in 1:4)
      edL2[[i]] <- list(edges=c(2,1,2,1)[i], weights=sqrt(i))
    gR2 <- graphNEL(nodes=V, edgeL=edL2, edgemode="directed")

    gX <- addEdge("A", "C", gR2, 1)

    gR3 <- randomEGraph(letters[10:14], .4)
    gY <- addEdge("n", "l", gR3, 1)

[Package graph version 1.72.0 Index]