graphAM-class {graph} | R Documentation

## Class "graphAM"

### Description

A graph class where node and edge information is represented as an adjacency matrix. The adjacency matrix is square and element `adjMat[i, j]` is one if there is an edge from node i to node j and zero otherwise.

### Details

The non-zero matrix values can be used to initialize an edge attribute. If this is desired, use the `values` argument in the call to `new` and provide a list with a single named element. The name determines the attributes and the value provides the default value for that attribute.

### Objects from the Class

Objects can be created by calls of the form `graphAM(adjMat, edgemode, values)`.

### Slots

`adjMat`:

  An adjacency `"matrix"` describing the graph structure. The `colnames` of the matrix will be used as node names for the graph if present.

`edgeData`:

  Storage for edge attributes.

`nodeData`:

  Storage for node attributes.

### Extends

Class `"graph"`, directly.

### Constructor

`graphAM(adjMat=matrix(integer(), 0, 0), edgemode='undirected', values=NA)` creates a graphAM instance.

adjMat

  An `integer` matrix specifying which nodes have edges between them.

edgemode

  Either "directed" or "undirected".

values

  A named list of length 1, used (rather obscurely) to specify that non-zero adjMat values initialize an edge attribute. The name of the single element in that list becomes the name of that attribute, with the specified default value. This default value is, however, never used: the specified edge attribute always has the value contained in the adjacency matrix, which is traditionally 1, but can be any positive number.

### Methods

addEdge

  `signature(from = "character", to = "character", graph = "graphAM", weights = "missing")`: ...

addNode

  `signature(object = "graphAM", nodes = "character")`: ...

clearNode

  `signature(node = "character", object = "graphAM")`: ...

coerce

  `signature(from = "graphAM", to = "graphNEL")`: ...

coerce

  `signature(from = "graphAM", to = "graphBAM")`: ...

coerce

  `signature(from = "graphAM", to = "matrix")`: In converting to a `matrix`, if an edge attribute named `"weight"` is defined, the non-zero elements of the matrix will contain the corresponding attribute value. For more flexible matrix conversion, see `toMatrix`.

coerce

  `signature(from = "matrix", to = "graphAM")`: This coerce method exists for symmetry. In most cases, creating a new `graphAM` instance using `new` gives one more control over the resulting graph.

edges

  `signature(object = "graphAM")`: ...

initialize

  `signature(.Object = "graphAM")`: ...

inEdges

  `signature(node = "character", object = "graphNEL")`: Return the incoming edges for the specified nodes. See `inEdges`.

isAdjacent

  `signature(object = "graphAM", from = "character", to = "character")`: ...

nodes<-

  `signature(object = "graphAM", value = "character")`: ...

nodes

  `signature(object = "graphAM")`: ...

numEdges

  `signature(graph = "graphAM")`: ...

numNodes

  `signature(object = "graphAM")`: ...

removeEdge

  `signature(from = "character", to = "character", graph = "graphAM")`: ...

removeNode

  `signature(node = "character", object = "graphAM")`: ...

### Author(s)

Seth Falcon

### See Also

`graph-class`, `graphNEL-class`

### Examples

    mat <- rbind(c(0, 0, 1, 1),
                 c(0, 0, 1, 1),
                 c(1, 1, 0, 1),
                 c(1, 1, 1, 0))
    rownames(mat) <- colnames(mat) <- letters[1:4]
    g1 <- graphAM(adjMat=mat)
    stopifnot(identical(mat, as(g1, "matrix")), validObject(g1))

    ## now with weights:
    mat[1,3] <- mat[3,1] <- 10
    gw <- graphAM(adjMat=mat, values=list(weight=1))

    ## consistency check:
    stopifnot(identical(mat, as(gw, "matrix")),
              validObject(gw),
              identical(gw, as(as(gw, "graphNEL"), "graphAM")))

[Package graph version 1.68.0 Index]