Simplify a Network

Removes self-loops and (where representable) merges duplicate (multi-)edges, similar to igraph::simplify().

Usage

simplify(x, remove_loops, remove_multiple, edge_attr_comb, ...)

# S3 method for class 'matrix'
simplify(
  x,
  remove_loops = TRUE,
  remove_multiple = TRUE,
  edge_attr_comb = "mean",
  ...
)

# S3 method for class 'cograph_network'
simplify(
  x,
  remove_loops = TRUE,
  remove_multiple = TRUE,
  edge_attr_comb = "mean",
  ...
)

# S3 method for class 'igraph'
simplify(
  x,
  remove_loops = TRUE,
  remove_multiple = TRUE,
  edge_attr_comb = "mean",
  ...
)

# S3 method for class 'tna'
simplify(
  x,
  remove_loops = TRUE,
  remove_multiple = TRUE,
  edge_attr_comb = "mean",
  ...
)

# Default S3 method
simplify(
  x,
  remove_loops = TRUE,
  remove_multiple = TRUE,
  edge_attr_comb = "mean",
  ...
)

Arguments

x

Network input (matrix, cograph_network, igraph, tna object).

remove_loops

Logical. Remove self-loops (diagonal entries)? Default TRUE.

remove_multiple

Logical. Merge duplicate edges? Default TRUE. Ignored for matrix and tna inputs (see Details).

edge_attr_comb

How to combine weights of duplicate edges: "sum", "mean" (default), "max", "min", "first", or a custom function. Ignored for matrix and tna inputs.

...

Additional arguments (currently unused).

Value

The simplified network, in the same format and class as the input (matrix in / matrix out, cograph_network in / cograph_network out, and so on). The default method raises an error for any other class.

Details

The extent of simplification depends on the input representation:

• matrix and tna: edges are stored as an n x n weight matrix. Each cell (i, j) is unique by construction, so duplicate-edge merging has no effect and remove_multiple and edge_attr_comb are ignored. Only self-loops (the diagonal) are removed. Duplicate aggregation requires a cograph_network or igraph input.

• cograph_network: duplicate edges in the edge list are merged, and their weights are combined with edge_attr_comb.

• igraph: delegates to igraph::simplify(). The weight attribute is combined with edge_attr_comb and other edge attributes are dropped.

See also

filter_edges for conditional edge removal, centrality which has its own simplify parameter

Examples

# igraph also exports simplify(); qualify the call when both are loaded.
cograph::simplify(cograph(student_interactions), edge_attr_comb = "sum")
#> Cograph network: 34 nodes, 220 edges ( directed )
#> Source: edgelist 
#> Data: data.frame (389 x 2) 
#>   Nodes (34): Ac, Ad, Fi, Ik, Vx, Rt, ... +28 more
#> Weights: 1 to 14 
#> Layout: none 
#>   Use as.data.frame() for the edge table, as.data.frame(what = "nodes") for the nodes.