Module adjacency 

Dense integer adjacency-matrix constructor (ALGO-CN-029).

Counterpart of igraph_adjacency() in references/igraph/src/constructors/adjacency.c:335-386.

Builds a Graph from a square n × n integer matrix whose entries are edge multiplicities (non-negative). The shape of the resulting graph (directed / undirected, which triangle drives the edge count, how the diagonal becomes self-loops) is controlled by two enums:

• AdjacencyMode — one of seven dispatch flavours (Directed, Undirected, Max, Min, Plus, Upper, Lower).
• LoopsMode — how to interpret the diagonal: NoLoops zeroes it, Once treats A(i,i) as the loop count, Twice treats it as twice the loop count (must be even).

For consistency with upstream igraph the Twice request is silently collapsed to Once for the Directed, Upper and Lower modes — the matrix only stores one copy of each loop in those layouts.

Matrix layout: &[&[i64]] — a slice of equal-length rows in row-major form. Every row must have the same length as the outer slice; ragged input is rejected. A 0 × 0 matrix produces an empty graph (matching the C semantics for an IGRAPH_MATRIX_NULL of shape 0 × 0).

Time complexity: O(|V|² + |E|).

Enums

AdjacencyMode

How to interpret the input matrix as an adjacency matrix.

LoopsMode

How to convert diagonal entries into self-loops.

Functions

adjacency

Build a graph from a dense integer adjacency matrix.