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Convert relational data to a plotit graph

Source: R/graph.R
as_graph.Rd

Coerces edge lists, adjacency matrices, contingency tables, cluster trees, or tbl_graph objects into a plotit_graph: a named list of data frames (nodes, edges) that can initialize plotit() and be positioned by layout_*() transforms. Layout coordinates are never mapped by hand – they are produced by layouts and bound automatically at mark time.

Usage

as_graph(
  edges,
  nodes = NULL,
  source = "source",
  target = "target",
  value = NULL,
  directed = FALSE
)

Arguments

edges

Primary relational input. One of:

  • a data.frame edge list (columns selected by source/target/value);

  • a matrix or xtabs/table of flows (melted automatically);

  • an hclust or dendrogram object;

  • a tbl_graph.

nodes

Optional node attribute table. Must contain a column named id. When omitted, nodes are generated implicitly from the edge endpoints in first-appearance order.

source, target

Column names (bare or quoted) locating the edge endpoints in edges. Defaults "source" / "target".

value

Column name (bare or quoted) holding flow magnitudes. Defaults to a column named "value" when present, otherwise unit weights are used. The output column is always named value.

directed

Logical; whether the relation is directed.

Value

An S3 plotit_graph object: a named list with at least nodes (id column first) and edges (source, target, value).

Examples

e <- data.frame(source = c("a", "b"), target = c("b", "c"))
g <- as_graph(e)
names(g)
#> [1] "nodes" "edges"
g$edges
#>   source target value
#> 1      a      b     1
#> 2      b      c     1