Add and remove edges from a gGraph object

The function setEdges allows one to add or remove edges in a gGraph by directly specifying the relevant nodes, as a list or a data.frame. This low-level function is called by geo.add.edges and geo.remove.edges.

Usage

setEdges(x, ...)

# S4 method for class 'gGraph'
setEdges(x, add = NULL, remove = NULL, costs = NULL, ...)

Arguments

x

a valid gGraph object.

...

other arguments passed to other methods (currently unused).

add

a list or a dataframe containing node names of edges to be added. The first element of the list (or column of the data.frame) gives starting nodes of edges; the second gives ending nodes. Hence, the nodes of the i-th edge are add[[1]][i] and add[[2]][i] if add is a list, and add[i,] if add is a data.frame.

remove

same as add argument, but edges are removed.

costs

a numeric vector providing costs of the edges to be added. costs[i] is the weight of the i-th edge.

Value

A gGraph object with newly added or removed edges.

Functions

• setEdges(gGraph): Method for gGraph object

See also

getEdges to retrieve edges. geo.add.edges and geo.remove.edges for interactive versions.

Examples

# check which nodes are neighbours of node "1"
head(getEdges(worldgraph.10k, res.type = "matNames"))
#>      Vi   Vj    
#> [1,] "67" "9955"
#> [2,] "67" "387" 
#> [3,] "67" "68"  
#> [4,] "67" "9953"
#> [5,] "67" "388" 
#> [6,] "68" "388" 

# remove an edge between two neighbouring nodes
node.from <- "1"
node.to <- getEdges(worldgraph.10k, res.type = "matNames")[1, 2]

x <- setEdges(worldgraph.10k,
  remove = data.frame(from = node.from, to = node.to)
)

# verify the edge is gone
areNeighbours(node.from, node.to, getGraph(x))
#> 1->9955 
#>   FALSE 

# add it back
x <- setEdges(x, add = data.frame(from = node.from, to = node.to))
areNeighbours(node.from, node.to, getGraph(x))
#> 1->9955 
#>    TRUE