cograph (version 2.7.2)

shortest_paths: Compute Shortest Path Distances

Description

Computes shortest path distances between nodes in a network. Supports all-pairs, single-source, and point-to-point queries.

Usage

shortest_paths(x, from = NULL, to = NULL, weights = NULL, directed = NULL, ...)

Value

Depends on the query:

• If both from and to are NULL: a full distance matrix (all pairs)

• If from is a single node and to is NULL: a named numeric vector of distances from that node to all others

• If from is multiple nodes and to is NULL: a matrix with rows for each source

• If both from and to are single nodes: a single numeric value

• Otherwise: a matrix of distances between the specified node sets

Arguments

x

Network input: matrix, igraph, network, cograph_network, or tna object

from

Character or numeric node identifier(s) for the source. If NULL (default), compute distances from all nodes.

to

Character or numeric node identifier(s) for the target. If NULL (default), compute distances to all nodes.

weights

Edge weight handling: NULL (default) auto-detects from edge attributes, NA forces unweighted distances, or a numeric vector of custom weights.

directed

Logical or NULL. If NULL (default), auto-detect from matrix symmetry. Set TRUE to force directed, FALSE to force undirected.

...

Currently unused; directed is already an explicit argument above and to_igraph accepts no others.

Details

Uses igraph::distances() internally. For weighted networks, edge weights are used as distances by default. Pass weights = NA to ignore weights and treat all edges as having unit distance.

Note: igraph::distances() with weights = NULL automatically uses edge weight attributes if present. To force unweighted computation, pass weights = NA explicitly.

igraph also exports a shortest_paths() with a different signature and return value; when both packages are attached, qualify the call as cograph::shortest_paths().

See Also

k_shortest_paths, network_summary

Examples

# All-pairs distances
adj <- matrix(c(
  0, 1, 0, 0,
  1, 0, 1, 0,
  0, 1, 0, 1,
  0, 0, 1, 0
), 4, 4)
rownames(adj) <- colnames(adj) <- LETTERS[1:4]
cograph::shortest_paths(adj)

# Single source to all
cograph::shortest_paths(adj, from = "A")

# Point-to-point
cograph::shortest_paths(adj, from = "A", to = "D")