# C/igraph 0.9.0 **URL:** \ **Category:** Announcements\ **Tags:** C\ **Created:** [16 February 2021 16:54 UTC](https://igraph.discourse.group/t/c-igraph-0-9-0/629 "2021-02-16T16:54:42Z")\ **Posts on this page:** 1\ **Page:** 1
**Author:** ![szhorvat](https://yyz2.discourse-cdn.com/free1/user_avatar/igraph.discourse.group/szhorvat/32/3_2.png) [@szhorvat](https://igraph.discourse.group/u/szhorvat)\ **Post date:** [16 February 2021 16:54 UTC](https://igraph.discourse.group/t/c-igraph-0-9-0/629/1 "2021-02-16T16:54:43Z")
Release 0.9.0 of igraph’s C core has arrived, almost exactly one year after version 0.8.0. This release brings several new features and improvements, and also a complete switch from the old `autotools`-based build system to a new one based on CMake. This results in faster build times and the opportunity to use alternative build tools instead of `make`; in particular, igraph now supports `ninja` and can also make use of a locally installed `ccache` compiler cache for even faster builds. Installation instructions are [on the website](https://igraph.org/c/#startc) and included in the documentation, which is now bundled with the release. We gratefully acknowledge support from the [Chan Zuckerberg Initiative](https://chanzuckerberg.com) for the development of igraph. In addition, we would like to thank everyone who reported issues, contributed features or fixes, or edited the documentation. igraph is an open-source project run by volunteers. _As always, your contributions are very welcome!_ Most people use igraph through its high-level interfaces for [R](https://igraph.org/r/), [Python](https://igraph.org/python/) or [Mathematica](http://szhorvat.net/mathematica/IGraphM). A new release of the Python interface, based on 0.9.0, is expected to be released in a few days. The Mathematica interfaces already includes some of the improvements, and along with the R interface it will continue to integrate more. The sources can be obtained from [the GitHub releases page](https://github.com/igraph/igraph/releases/tag/0.9.0). The summary of changes is below. ### Added - Eulerian paths/cycles (PR #1346): - `igraph_is_eulerian()` finds out whether an Eulerian path/cycle exists. - `igraph_eulerian_path()` returns an Eulerian path. - `igraph_eulerian_cycle()` returns an Eulerian cycle. - Efficiency (PR #1344): - `igraph_global_efficiency()` computes the global efficiency of a network. - `igraph_local_efficiency()` computes the local efficiency around each vertex. - `igraph_average_local_efficiency()` computes the mean local efficiency. - Degree sequences (PR #1445): - `igraph_is_graphical()` checks if a degree sequence has a realization as a simple or multigraph, with or without self-loops. - `igraph_is_bigraphical()` checks if two degree sequences have a realization as a bipartite graph. - `igraph_realize_degree_sequence()` now supports constructing non-simple graphs as well. - There is a new fatal error handling mechanism (PR #1548): - `igraph_set_fatal_handler()` sets the fatal error handler. It is the only function in this functionality group that is relevant to end users. - The macro `IGRAPH_FATAL()` and the functions `igraph_fatal()` and `igraph_fatalf()` raise a fatal error. These are for internal use. - `IGRAPH_ASSERT()` is a replacement for the `assert()` macro. It is for internal use. - `igraph_fatal_handler_abort()` is the default fatal error handler. - The new `IGRAPH_WARNINGF`, `IGRAPH_ERRORF` and `IGRAPH_FATALF` macros provide warning/error reporting with `printf`-like syntax. (PR #1627, thanks to Daniel Noom!) - `igraph_average_path_length_dijkstra()` computes the mean shortest path length in weighted graphs (PR #1344). - `igraph_get_shortest_paths_bellman_ford()` computes the shortest paths (including the vertex and edge IDs along the paths) using the Bellman-Ford algorithm (PR #1642, thanks to Guy Rozenberg). This makes it possible to calculate the shortest paths on graphs with negative edge weights, which was not possible before with Dijkstra’s algorithm. - `igraph_get_shortest_path_bellman_ford()` is a wrapper for `igraph_get_shortest_paths_bellman_ford()` for the single path case. - `igraph_is_same_graph()` cheks that two labelled graphs are the same (PR #1604). - Harmonic centrality (PR #1583): - `igraph_harmonic_centrality()` computes the harmonic centrality of vertices. - `igraph_harmonic_centrality_cutoff()` computes the range-limited harmonic centrality. - Range-limited centralities, currently equivalent to the old functions with names ending in `_estimate` (PR #1583): - `igraph_closeness_cutoff()`. - `igraph_betweenness_cutoff()`. - `igraph_edge_betweenness_cutoff()`. - `igraph_vector_is_any_nan()` checks if any elements of an `igraph_vector_t` is NaN. - `igraph_inclist_size()` returns the number of vertices in an incidence list. - `igraph_lazy_adjlist_size()` returns the number of vertices in a lazy adjacency list. - `igraph_lazy_inclist_size()` returns the number of vertices in a lazy incidence list. - `igraph_bfs_simple()` now provides a simpler interface to the breadth-first search functionality. ### Changed - igraph now uses a CMake-based build sysyem. - GMP support can no longer be disabled. When GMP is not present on the system, igraph will use an embedded copy of Mini-GMP (PR #1549). - Bliss has been updated to version 0.75. Bliss functions are now interruptible. Thanks to Tommi Junttila for making this possible! - Adjacency and incidence lists: - `igraph_adjlist_init()` and `igraph_lazy_adjlist_init()` now require the caller to specify what to do with loop and multiple edges. - `igraph_inclist_init()` and `igraph_lazy_inclist_init()` now require the caller to specify what to do with loop edges. - Adjacency and incidence lists now use `igraph_vector_int_t` consistently. - Community detection: - `igraph_community_multilevel()`: added resolution parameter. - `igraph_community_fluid_communities()`: graphs with no vertices or with one vertex only are now supported; they return a trivial partition. - Modularity: - `igraph_modularity()` and `igraph_modularity_matrix()`: added resolution parameter. - `igraph_modularity()` and `igraph_modularity_matrix()` now support the directed version of modularity. - `igraph_modularity()` returns NaN for graphs with no edges to indicate that the modularity is not well-defined for such graphs. - Centralities: - `cutoff=0` is no longer interpreted as infinity (i.e. no cutoff) in `betweenness`, `edge_betweenness` and `closeness`. If no cutoff is desired, use a negative value such as `cutoff=-1`. - The `nobigint` argument has been removed from `igraph_betweenness()`, `igraph_betweenness_estimate()` and `igraph_centralization_betweenness()`, as it is not longer needed. The current implementation is more accurate than the old one using big integers. - `igraph_closeness()` now considers only reachable vertices during the calculation (i.e. the closeness is calculated per-component in the undirected case) (PR #1630). - `igraph_closeness()` gained two additional output parameters, `reachable_count` and `all_reachable`, returning the number of reached vertices from each vertex, as well as whether all vertices were reachable. This allows for computing various generalizations of closeness for disconnected graphs (PR #1630). - `igraph_pagerank()`, `igraph_personalized_pagerank()` and `igraph_personalized_pagerank_vs()` no longer support the `IGRAPH_PAGERANK_ALGO_POWER` method. Their `options` argument now has type `igraph_arpack_options_t *` instead of `void *`. - Shortest paths (PR #1344): - `igraph_average_path_length()` now returns the number of disconnected vertex pairs in the new `unconn_pairs` output argument. - `igraph_diameter()` now return the result as an `igraph_real_t` instead of an `igraph_integer_t`. - `igraph_average_path_length()` and `igraph_diameter()` now return `IGRAPH_INFINITY` when `unconn=FALSE` and the graph is not connected. Previously they returned the number of vertices. - Trait-based random graph generators: - `igraph_callaway_traits_game()` and `igraph_establishment_game()` now have an optional output argument to retrieve the generated vertex types. - `igraph_callaway_traits_game()` and `igraph_establishment_game()` now allow omitting the type distribution vector, in which case they assume a uniform distribution. - `igraph_asymmetric_preference_game()` now accept a different number of in-types and out-types. - `igraph_subisomorphic_lad()` now supports graphs with self-loops. - `igraph_is_chordal()` and `igraph_maximum_cardinality_search()` now support non-simple graphs and directed graphs. - `igraph_realize_degree_sequence()` has an additional argument controlling whether multi-edges or self-loops are allowed. - `igraph_is_connected()` now returns false for the null graph; see [igraph\_diameter() mishandles null graph · Issue #1538 · igraph/igraph · GitHub](https://github.com/igraph/igraph/issues/1538) for the reasoning behind this decision. - `igraph_lapack_ddot()` is renamed to `igraph_blas_ddot()`. - `igraph_to_directed()`: added RANDOM and ACYCLIC modes (PR #1511). - `igraph_topological_sorting()` now issues an error if the input graph is not acyclic. Previously it issued a warning. - `igraph_vector_(which_)(min|max|minmax)()` now handles NaN elements. - `igraph_i_set_attribute_table()` is renamed to `igraph_set_attribute_table()`. - `igraph_i_sparsemat_view()` is renamed to `igraph_sparsemat_view()`. ### Deprecated - `igraph_is_degree_sequence()` and `igraph_is_graphical_degree_sequence()` are deprecated in favour of the newly added `igraph_is_graphical()`. - `igraph_closeness_estimate()` is deprecated in favour of the newly added `igraph_closeness_cutoff()`. - `igraph_betweenness_estimate()` and `igraph_edge_betweenness_estimate()` are deprecated in favour of the newly added `igraph_betweenness_cutoff()` and `igraph_edge_betweenness_cutoff()`. - `igraph_adjlist_remove_duplicate()` and `igraph_inclist_remove_duplicate()` are now deprecated in favour of the new constructor arguments in `igraph_adjlist_init()` and `igraph_inclist_init()`. ### Removed - The following functions, all deprecated in igraph 0.6, have been removed (PR #1562): - `igraph_adjedgelist_init()`, `igraph_adjedgelist_destroy()`, `igraph_adjedgelist_get()`, `igraph_adjedgelist_print()`, `igraph_adjedgelist_remove_duplicate()`. - `igraph_lazy_adjedgelist_init()`, `igraph_lazy_adjedgelist_destroy()`, `igraph_lazy_adjedgelist_get()`, `igraph_lazy_adjedgelist_get_real()`. - `igraph_adjacent()`. - `igraph_es_adj()`. - `igraph_subgraph()`. - `igraph_pagerank_old()`, deprecated in 0.7, has been removed. - `igraph_vector_bool` and `igraph_matrix_bool` functions that relied on inequality-comparing `igraph_bool_t` values are removed. ### Fixed - Betweenness calculations are no longer at risk from integer overflow. - The actual cutoff distance used in closeness calculation was one smaller than the `cutoff` parameter. This is corrected (PR #1630). - `igraph_layout_gem()` was not interruptible; now it is. - `igraph_barabasi_aging_game()` now checks its parameters more carefully. - `igraph_callaway_traits_game()` and `igraph_establishment_game()` now check their parameters. - `igraph_lastcit_game()` checks its parameters more carefully, and no longer crashes with zero vertices (PR #1625). - `igraph_cited_type_game()` incorrectly rounded the attractivity vector entries to integers. - `igraph_residual_graph()` now returns the correct _residual_ capacities; previously it wrongly returned the original capacities (PR #1598). - `igraph_psumtree_update()` now checks for negative values and NaN. - `igraph_communities_spinglass()`: fixed several memory leaks in the `IGRAPH_SPINCOMM_IMP_NEG` implementation. - `igraph_incident()` now returns edges in the same order as `igraph_neighbors()`. - `igraph_modularity_matrix()` returned incorrect results for weighted graphs. This is now fixed. (PR #1649, thanks to Daniel Noom!) - `igraph_lapack_dgetrf()` would crash when passing `NULL` for its `ipiv` argument (thanks for the fix to Daniel Noom). - Some `igraph_matrix` functions would fail to report errors on out-of-memory conditions. - `igraph_maxdegree()` now returns 0 for the null graph or empty vector set. Previously, it did not handle this case. - `igraph_vector_bool_all_e()` now considers all nonzero (i.e. “true”) values to be the same. - PageRank (PR #1640): - `igraph_(personalized_)pagerank(_vs)()` now check their parameters more carefully. - `igraph_personalized_pagerank()` no longer modifies its `reset` parameter. - `igraph_(personalized_)pagerank(_vs)`: the `IGRAPH_PAGERANK_ALGO_ARPACK` method now handles self-loops correctly. - `igraph_personalized_pagerank(_vs)()`: the result retuned for edgeless or all-zero-weight graphs with the `IGRAPH_PAGERANK_ALGO_ARPACK` ignored the personalization vector. This is now corrected. - `igraph_personalized_pagerank(_vs)()` with a non-uniform personalization vector, a disconnected graph and the `IGRAPH_PAGERANK_ALGO_PRPACK` method would return results that were inconsistent with `IGRAPH_PAGERANK_ALGO_ARPACK`. This happened because PRPACK always used a uniform reset distribution when the random walk got stuck in a sink vertex. Now it uses the user-specified reset distribution for this case as well. - Fixed crashes in several functions when passing a weighted graph with zero edges (due to `vector_min` being called on the zero-length weight vector). - Fixed problems in several functions when passing in a graph with zero vertices. - Weighted betweenness, closeness, PageRank, shortest path calculations and random walk functions now check if any weights are NaN. - Many functions now reject input arguments containing NaN values. - Compatibility with the PGI compiler. ### Other - Documentation improvements. - Improved error and warning messages. - More robust error handling. - General code cleanup to reduce the number of compiler warnings. - igraph’s source files have been re-organized for better maintainability. - Debugging aid: When igraph is build with AddressSanitizer, the default error handler prints a stack trace before exiting. - igraph can now be built with an external CXSparse library. - The references to igraph source files in error and warning messages are now always relative to igraph’s base directory. - When igraph is built as a shared library, only public symbols are exported even on Linux and macOS. ### Acknowledgments - Thanks to Daniel Noom for significantly expanding igraph’s test coverage and exposing several issues in the process!