@woosh/meep-engine/src/core/graph/graph_compute_adjacency_matrix.js

Pure JavaScript game engine. Fully featured and production ready.

import { assert } from "../assert.js";


/**
 * Computes the adjacency matrix of a graph.
 * Writes 1 to matrix elements where nodes are connected, leaves existing values where there are no connections.
 * Does NOT zero-fill the matrix before writing.
 * @template T Type of the graph's nodes.
 * @param {Graph<T>} graph Input graph.
 * @param {SquareMatrix} result Output: Adjacency matrix (modified in-place).
 * @param {Map<T,number>} node_indices Map from graph nodes to matrix indices.
 */
export function graph_compute_adjacency_matrix(graph, result, node_indices) {
    const edges = graph.getEdges();

    for (const edge of edges) {
        const a = node_indices.get(edge.first);
        const b = node_indices.get(edge.second);

        assert.isNonNegativeInteger(a, 'a');
        assert.isNonNegativeInteger(b, 'b');

        result.setCellValue(a, b, 1);
        result.setCellValue(b, a, 1);
    }
}