Changelog

[v1.0.0] - August 2026

Added

Markov chains (module: chain)

• Added ability to incrementally configure the chain.

  You can explicitly set class attributes, such as: chain.initial_partition = ....

  Functions to add constraints and updaters:

  • add_constraint()

  • add_constraints()

  • add_updater()

  • add_updaters()

  Function to check whether a chain is fully configured:

  • check_valid()

Graphs (module: graph)

• Added methods to query and access the embedded NetworkX/RustworkX graph.

  • is_nx_graph()

  • is_rx_graph()

  • get_nx_graph()

  • get_rx_graph()

• Added methods for converting between GerryChain, NetworkX, and RustworkX graphs, and to create an empty graph.

  • from_networkx()

  • from_rustworkx()

  • from_null_networkx()

  • to_networkx_graph()

• Added methods to translate node_ids between NetworkX and RustworkX and between parent graphs and subgraphs - to deal with the differences between the way NetworkX and RustworkX implement node_ids.

  • original_nx_node_id_for_internal_node_id()

  • internal_node_id_for_original_nx_node_id()

  • get_nx_to_rx_node_id_map()

  • translate_subgraph_node_ids_for_set_of_nodes()

  • original_nx_node_ids_for_list()

  • original_nx_node_ids_for_set()

  • translate_subgraph_node_ids_for_flips()

• Added methods to handle the fact that in RustworkX, edges are different from edge_ids. In both NetworkX and RustworkX, an edge is a tuple of node_ids. In NetworkX, there is no difference between an edge and an edge_id, but in RustworkX an edge_id is an integer.

  • get_edge_id_from_edge()

  • get_edge_from_edge_id()

Examples (module: examples)

• Added gerrymandria(), which returns the fictional 8x8 grid graph used in the User Guide.

Partitions (module: partition)

• Added Partition.assignment_vector() and Assignment.to_vector().

Proposals (module: proposals)

• Added new names for legacy functions. The new names adhere to the naming convention for creating proposal functions, “build_xxx_proposal_fn”. Note that the legacy functions continue to exist.

  • build_any_node_flip_proposal_fn() == propose_any_node_flip()

  • build_random_flip_proposal_fn() == propose_random_flip()

  • build_flip_every_district_proposal_fn() == propose_flip_every_district()

  • build_chunk_flip_proposal_fn() == propose_chunk_flip()

  • build_slow_reversible_proposal_fn() == slow_reversible_propose()

  • build_slow_reversible_bi_proposal_fn() == slow_reversible_propose_bi()

ReCom proposals (module: proposals)

• Changed the ReCom class to be a namespace that defines the five variants of recom that were discussed in the article, “Spanning Tree Methods for Sampling Graph Partitions”:

  • A = cut_edges_mst()

  • B = district_pairs_mst()

  • C = cut_edges_ust()

  • D = district_pairs_ust()

  • R = reversible()

• Added convenience functions to create recom proposal functions:

  • build_recom_proposal_fn()

  • build_reversible_recom_proposal_fn()

Multi-member ReCom (module: proposals)

• Added functions and the MultiMemberReCom class to support multi-member ReCom. These new functions and the MultiMemberReCom class mirror the routines and class for standard ReCom:

  • multi_member_recom()

  • build_multi_member_recom_proposal_fn()

  • epsilon_tree_bipartition_multi_member()

  • class MultiMemberReCom

    • cut_edges_mst()

    • district_pairs_mst()

    • cut_edges_ust()

    • district_pairs_ust()

Constraints for multi-member ReCom (module: constraints)

• Added a new constraint to support multi-member ReCom

  • within_percent_of_ideal_population_per_member()

Changed

Graphs

• gerrychain.Graph no longer subclasses networkx.Graph. Node and edge data access has changed. See the v1.0 migration guide.

• Changed the way to access node and edge data

  • To access node data, use: my_graph.node_data(…node_id…)

  • To access edge data, use: my_graph.edge_data(…edge_id…)

• GerryChain now uses independent random number generators configured through rng=. See the reproducibility guide.

Renamed public parameters

• Parameters accepting functions now generally have names that use the _fn suffix:

  This is only an issue for function calls using named parameters.

  An example of this is the renaming of “proposal” to “proposal_fn” in the constructor for a MarkovChain object:

  Old:

  my_chain = MarkovChain(
      proposal = my_proposal,
      ...
  )
  

  New:

  my_chain = MarkovChain(
      proposal_fn = my_proposal,
      ...
  )
  

Removed

Removed the pre-1.0 NetworkX-derived Graph interface.

• gerrychain.Graph is no longer a subclass of networkx.Graph. See the v1.0 migration guide for replacement graph operations.

Removed the old instantiable and callable ReCom interface.

• The old ReCom class was instantiable and callable. It has been replaced with a namespace that defines functions that generate proposal functions. See The ReCom Namespace for details.

Other removals

• MarkovChain is now an iterable rather than an iterator. Create an iterator with chain_iterator = iter(chain), then call next(chain_iterator) instead of next(chain).

• Removed gerrychain.__version__. Use importlib.metadata.version("gerrychain") to read the installed package version.

Deprecated

Pre-1.0 callback signatures

• Legacy proposal, acceptance, spanning-tree, bipartition, balanced-edge-cut, cut-choice, and initial-partition callbacks remain temporarily supported with warnings. This includes callbacks that do not accept rng=.

  For more details see the reproducibility guide.

Legacy parameter names

• The legacy parameter names listed above remain temporarily supported with warnings.

• create_grid_graph() remains available as a deprecated compatibility shim. There is no public create_grid_nx_graph() function.