igraph

Added

• igraph_matrix_init_array() to initialize an igraph matrix by copying an existing C array in column-major or row-major order.
• igraph_layout_umap_compute_weights() computes weights for the UMAP layout algorithm from distances. This used to be part of igraph_layout_umap(), but it is now in a separate function to allow the user to experiment with different weighting schemes.
• igraph_triangular_lattice() to generate triangular lattices of various kinds (#2235, thanks to @rfulekjames).
• igraph_hexagonal_lattice() to generate hexagonal lattices of various kinds (#2262, thanks to @rfulekjames).
• igraph_tree_from_parent_vector() to create a tree or a forest from a parent vector (i.e. a vector that encodes the parent vertex of each vertex).
• igraph_induced_subgraph_edges() produces the IDs of edges contained within a subgraph induced by the given vertices.

• The signature of the experimental igraph_layout_umap() function changed; the last argument is now a Boolean that specifies whether distances should already be treated as weights, and the sampling probability argument was removed.

• igraph_transitivity_barrat(), igraph_community_fluid_communities(), igraph_sir(), igraph_trussness() and graphlet functions did not correctly detect when a directed input graph had effective multi-edges due to ignoring edge directions. Such graphs are now rejected by these functions.
• Fixed a bug in igraph_2dgrid_move() that sometimes crashed the Large Graph Layout function when a grid cell became empty.
• igraph_pagerank() and igraph_personalized_pagerank() would fail to converge when the ARPACK implementation was used and a vertex had more than one outgoing edge but all these edges had zero weights.
• igraph_pagerank() and igraph_personalized_pagerank() no longer allow negative weights. Previously, edges with negative weights were silently ignored when using the PRPACK implementation. The ARPACK implementation would issue a warning saying that they are ignored, but in fact it computed an incorrect result.
• igraph_all_st_cuts() and igraph_all_st_mincuts() no longer trigger the "Finally stack too large" fatal error when called on certain large graphs. This was a regression in igraph 0.10.
• igraph_community_label_propagation() no longer rounds weights to integers. This was a regression in igraph 0.10.
• igraph_read_graph_graphdb() does more thorough checks on the input file.
• igraph_calloc() did not zero-initialize the allocated memory. This is now corrected. Note that the macro IGRAPH_CALLOC() was not affected.
• Fixed new warnings issued by the Xcode 14.1 toolchain.

• igraph_subgraph_edges() is now deprecated to avoid confusion with igraph_induced_subgraph_edges(); its new name is igraph_subgraph_from_edges(). The old name is kept available until at least igraph 0.11.

• Significantly improved performance for igraph_matrix_transpose().
• Documentation improvements.