igraph for R: R interface of the igraph library for graph theory and network analysis

New features

• Add make_wheel() to expose igraph_wheel() (#1561, #2409).

• Add transitive_closure() function to compute the transitive closure of a graph (#1350, #2413).

• Add make_full_multipartite() and make_turan() graph constructors (#1562, #2406).

• Add count_loops() (#1379, #2414).

• Add make_circulant() to expose igraph_circulant() (#1563, #2407).

• Add mean_degree() (#1380, #2415).

• Add count_reachable() function (#1349, #2412).

• Add invalidate_cache() (#1387, #2416).

• graphlet_basis() returns a list of vertices in the "cliques" component instead of a raw integer matrix (#2470, #2472).

• vertices() now errors on duplicate attribute names (#1248, #2430).

• Implement generic mechanism for layout_() modifiers, allowing layout algorithms to be composed and adjusted uniformly (#1473, #2435).

• Change graph constructors to use explicit named arguments instead of positional ones (#2466, #2467).

• Improve formatting of error messages originating from the C library (#2202, #2515).

• Functions that accept a single vertex now check that exactly one vertex is passed (#2556).

Bug fixes

• Error call in with_vertex_()/with_edge_() should report the public make_() function, not the internal helper (#2609).

• Not all loops are plotted when a graph has multiple loops at the same vertex (#2594, #2595).

• Fix hrg_game_impl() which produced incorrect results (#2577, #2578).

• graphlet_proj() no longer erroneously assigns class "igraphHRG" to the returned graph.

• Support character labels in assortativity_nominal() in addition to integer type codes (#1283, #2432).

• Fix uninitialized variable warnings when building with R 4.5 on Windows (#2526, #2527).

• modularity() now uses the "weights" edge attribute automatically when no weights argument is supplied.

• Fix alpha_centrality() crash when weights is set to a custom edge attribute name rather than a numeric vector (#915, #2403).

• Fix matrix lists for output when returning multiple matrices from C.

Documentation

• Error messages throughout the package now use the cli package for consistent, styled output instead of base R stop() (#731, #2588).

• The R Consortium is listed as a funder with its ROR ID in the package metadata (#2587).

• Fixes to the pkgdown reference index (#2590, #2592).

• Documentation pages for R functions now automatically link to the corresponding C library documentation (#2518).

Testing

• Structured unit tests alongside snapshot tests have been added for all autogenerated _impl functions in test-aaa-auto.R, verifying argument passing and return values (#2448, #2449).

Internal

• The R interface for most C library functions is now autogenerated using the py-stimulus framework, covering 108+ functions including BFS and DFS callbacks, leading-eigenvector community detection, motif callbacks, sparse matrix operations, and graph-list constructors. Arguments use snake_case naming throughout for consistency (#2152, #2424, #2442, #2461, #2462, #2464, #2465, #2484, #2485, #2531, #2532, #2533, #2534, #2540, #2550, #2551, #2552, #2553, #2554, #2555).

• Most direct .Call() invocations to C library functions have been replaced with autogenerated _impl() wrapper functions that use explicit named arguments, covering all R source files (R/assortativity.R, R/bipartite.R, R/centrality.R, R/centralization.R, R/cliques.R, R/coloring.R, R/embedding.R, R/flow.R, R/games.R, R/layout.R, R/make.R, R/other.R, R/simple.R, R/structural-properties.R, R/topology.R, R/trees.R, R/triangles.R, and others) (#2332, #2334, #2345, #2347, #2348, #2351, #2352, #2355, #2357, #2358, #2359, #2361, #2362, #2363, #2364, #2365, #2366, #2367, #2368, #2369, #2370, #2372, #2373, #2374, #2379, #2380, #2382, #2383, #2384, #2386, #2388, #2398, #2422, #2423, #2428, #2429, #2434, #2443, #2471, #2476, #2477, #2478, #2539, #2541, #2545, #2546).