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Add edges to a GraphSpace object

Source: R/gspace-addition.R
gs_add_edges.Rd

gs_add_edges<- adds one or more edges to a GraphSpace object. Both endpoints of every new edge must already exist in the node set. The @graph, @edges, and all derived edge quantities are updated consistently; the node set and the normalized coordinate state are not affected.

Usage

# S4 method for class 'GraphSpace'
gs_add_edges(x) <- value

Arguments

x

A GraphSpace object.

value

A data frame with at least two columns identifying the edge endpoints. Two column naming conventions are accepted:

  • from / to — the tidygraph / igraph convention.

  • name1 / name2 — the @edges slot convention, useful when constructing value directly from gs_edges().

If both conventions are present, from/to takes priority. Any additional columns are treated as edge attributes and passed through to @edges. Standard visual attributes (edgeColor, arrowType, etc.) are filled from package defaults when omitted; analytical attributes such as weight are stored as-is.

Value

A GraphSpace object with the new edges appended.

Details

Adding edges does not invalidate the normalized layout. Node coordinates in @nodes are left untouched and normalizeGraphSpace does not need to be re-run.

For objects built with simplify = TRUE (the default), loop edges (from == to), parallel edges, and duplicate rows within value are silently dropped with a warning. Admissible edges in the same call are still added. To allow loops or parallel edges, rebuild the object with GraphSpace(g, simplify = FALSE).

Because adding an edge to a group of parallel edges changes the derived attributes curve_weight, is_multiple, and is_loop for all members of that group, the full edge table is recomputed from @graph after each assignment.

See also

gs_add_nodes<-, gs_edge_attr<-, gs_subset_edges, gs_edges

Examples

library(RGraphSpace)
library(igraph)

g <- make_star(5, mode = "out")
gs <- GraphSpace(g)
#> Validating the 'igraph' object...
#> Vertex attributes 'x' and 'y' missing; computing layout...
#> Vertex attribute 'name' missing; assigning names... 
#> Ignoring graph-level attributes: 'name', 'mode', 'center'
#> Creating a 'GraphSpace' object...
gs <- normalizeGraphSpace(gs)
#> Normalizing node coordinates to graph space...

# Add a single edge using from/to convention
gs_add_edges(gs) <- data.frame(from = "n2", to = "n3")

# Add multiple edges with an analytical attribute
gs_add_edges(gs) <- data.frame(
  from   = c("n2", "n3"),
  to     = c("n4", "n5"),
  weight = c(0.8, 0.4)
)

# name1/name2 convention also accepted (e.g. from gs_edges() output)
gs_add_edges(gs) <- data.frame(name1 = "n2", name2 = "n3")
#> Warning: ! 1 parallel edge(s) ignored: simplified GraphSpace do not allow parallel edges.
#> ℹ n2 -> n3
#> • Rebuild with GraphSpace(g, simplify = FALSE) to allow parallel edges.