# Coercion from Matrices to Network Objects

### Description

`as.network.matrix`

attempts to coerce its first argument to an object of class `network`

.

### Usage

1 2 3 4 5 6 7 |

### Arguments

`x` |
a matrix containing an adjacency structure |

`matrix.type` |
one of |

`directed` |
logical; should edges be interpreted as directed? |

`hyper` |
logical; are hyperedges allowed? |

`loops` |
logical; should loops be allowed? |

`multiple` |
logical; are multiplex edges allowed? |

`bipartite` |
count; should the network be interpreted as bipartite? If present (i.e., non-NULL) it is the count of the number of actors in the bipartite network. In this case, the number of nodes is equal to the number of actors plus the number of events (with all actors preceding all events). The edges are then interpreted as nondirected. |

`ignore.eval` |
logical; ignore edge values? |

`names.eval` |
optionally, the name of the attribute in which edge values should be stored |

`na.rm` |
logical; ignore missing entries when constructing the network? |

`edge.check` |
logical; perform consistency checks on new edges? |

`...` |
additional arguments |

### Details

Depending on `matrix.type`

, one of three edgeset constructor methods will be employed to read the input matrix (see `edgeset.constructors`

). If `matrix.type==NULL`

, `which.matrix.type`

will be used to guess the appropriate matrix type.

The coercion methods will recognize and attempt to utilize the `sna`

extended matrix attributes where feasible. These are as follows:

`"n"`

: taken to indicate number of vertices in the network.`"bipartite"`

: taken to indicate the network's`bipartite`

attribute, where present.`"vnames"`

: taken to contain vertex names, where present.

These attributes are generally used with edgelists, and indeed data in `sna`

edgelist format should be transparently converted in most cases. Where the extended matrix attributes are in conflict with the actual contents of `x`

, results are no guaranteed (but the latter will usually override the former). For an edge list, the number of nodes in a network is determined by the number of unique nodes specified. If there are isolate nodes not in the edge list, the "n" attribute needs to be set. See example below.

### Value

An object of class `network`

### Author(s)

Carter T. Butts buttsc@uci.edu and David Hunter dhunter@stat.psu.edu

### References

Butts, C. T. (2008). “network: a Package for Managing Relational Data in R.” *Journal of Statistical Software*, 24(2). http://www.jstatsoft.org/v24/i02/

### See Also

`edgeset.constructors`

, `network`

, `which.matrix.type`

### Examples

1 2 3 4 5 6 7 8 9 10 11 | ```
#Draw a random matrix
m<-matrix(rbinom(25,1,0.5),5)
diag(m)<-0
#Coerce to network form
g<-as.network.matrix(m,matrix.type="adjacency")
# edge list example. Only 4 nodes in the edge list.
m = matrix(c(1,2, 2,3, 3,4), byrow = TRUE, nrow=3)
attr(m, 'n') = 7
as.network(m, matrix.type='edgelist')
``` |