# Remove Elements from a Network Object

### Description

`delete.edges`

removes one or more edges (specified by their internal ID numbers) from a network; `delete.vertices`

performs the same task for vertices (removing all associated edges in the process).

### Usage

1 2 | ```
delete.edges(x, eid)
delete.vertices(x, vid)
``` |

### Arguments

`x` |
an object of class |

`eid` |
a vector of edge IDs. |

`vid` |
a vector of vertex IDs. |

### Details

Note that an edge's ID number corresponds to its order within `x$mel`

. To determine edge IDs, see `get.edgeIDs`

. Likewise, vertex ID numbers reflect the order with which vertices are listed internally (e.g., the order of `x$oel`

and `x$iel`

, or that used by `as.matrix.network.adjacency`

). When vertices are removed from a network, all edges having those vertices as endpoints are removed as well. When edges are removed, the remaining edge ids are NOT permuted and `NULL`

elements will be left on the list of edges, which may complicate some functions that require eids (such as `set.edge.attribute`

). The function `valid.eids`

provides a means to determine the set of valid (non-NULL) edge ids.

Edges can also be added/removed via the extraction/replacement operators. See the associated man page for details.

### Value

Invisibly, a pointer to the updated network; these functions modify their arguments in place.

### Author(s)

Carter T. Butts buttsc@uci.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

`get.edgeIDs`

, `network.extraction`

, `valid.eids`

### Examples

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 | ```
#Create a network with three edges
m<-matrix(0,3,3)
m[1,2]<-1; m[2,3]<-1; m[3,1]<-1
g<-network(m)
as.matrix.network(g)
delete.edges(g,2) #Remove an edge
as.matrix.network(g)
delete.vertices(g,2) #Remove a vertex
as.matrix.network(g)
#Can also remove edges using extraction/replacement operators
g<-network(m)
g[1,2]<-0 #Remove an edge
g[,]
g[,]<-0 #Remove all edges
g[,]
``` |