redistricting-analysis

Redistricting Analysis with the redistverse

A comprehensive reference for redistricting analysis in R using the redistverse ecosystem (library(redistverse) loads redist, redistmetrics, ggredist, geomander, sf, and adj).

Standard Analysis Pipeline

1. Load data — Download pre-built precinct map + demographics + elections via alarmdata, or assemble your own sf object and build a redist_map. → [12-alarmdata.md](references/12-alarmdata.md)
2. Prepare adjacency — Verify and edit the adjacency graph (remove water-body edges, fix topological errors). → [08-adj.md](references/08-adj.md), [09-geomander-adjacency.md](references/09-geomander-adjacency.md)
3. Set constraints — Define population tolerance, county-split penalties, VRA hinge constraints, compactness. → [02-redist-constraints.md](references/02-redist-constraints.md)
4. Simulate — Run redist_smc() (recommended) or MCMC to generate an ensemble of valid plans. → [01-redist-simulation.md](references/01-redist-simulation.md)
5. Validate — Check convergence (summary()), R-hat, effective sample size, and plan diversity. → [01-redist-simulation.md](references/01-redist-simulation.md)
6. Score — Compute compactness, partisan fairness, splits, and other metrics across the ensemble. → [04–06 redistmetrics references](references/04-redistmetrics-compactness.md)
7. Visualize & compare — Map plans, plot metric distributions, compare enacted plan to the baseline. → [07-ggredist.md](references/07-ggredist.md)

Quick Navigation

| Package / Topic | Reference |

|----------------|-----------|

| redist_map, redist_smc, redist_mergesplit, redist_flip, redist_plans, diagnostics | [01-redist-simulation.md](references/01-redist-simulation.md) |

| redist_constr, add_constr_splits, add_constr_grp_hinge, all soft constraints | [02-redist-constraints.md](references/02-redist-constraints.md) |

| redist_enumpart, redist_shortburst, redist_cyclewalk, init_particles | [03-redist-advanced.md](references/03-redist-advanced.md) |

| redistmetrics — Polsby-Popper, Reock, spanning tree, prep_perims, comp_* functions | [04-redistmetrics-compactness.md](references/04-redistmetrics-compactness.md) |

| redistmetrics — efficiency gap, mean-median, bias, declination, part_* functions | [05-redistmetrics-partisan.md](references/05-redistmetrics-partisan.md) |

| redistmetrics — county splits, segregation, competitiveness, incumbents, plan_parity, group_frac | [06-redistmetrics-other.md](references/06-redistmetrics-other.md) |

| ggredist — geom_district, party color scales, cartographic palettes, theme_map | [07-ggredist.md](references/07-ggredist.md) |

| adj — adjacency graph construction, edge operations, coloring, Laplacian | [08-adj.md](references/08-adj.md) |

| geomander — adjacency construction, contiguity checks, seam_rip, edge editing | [09-geomander-adjacency.md](references/09-geomander-adjacency.md) |

| geomander — geo_match, estimate_down/up, block2prec, spatial estimation | [10-geomander-spatial.md](references/10-geomander-spatial.md) |

| geomander — downloading VEST, ALARM, DRA, HEDA, get_lewis election data | [11-geomander-data.md](references/11-geomander-data.md) |

| alarmdata — alarm_50state_map, pre-built datasets, caching, alarm_add_plan | [12-alarmdata.md](references/12-alarmdata.md) |

| PL94171 — Census P.L. 94-171 decennial data ingestion | [13-pl94171.md](references/13-pl94171.md) |

| censable (data + state IDs), easycensus (ACS), tinytiger (TIGER shapefiles) | [14-census-utilities.md](references/14-census-utilities.md) |

| baf — download official Census Bureau block assignment files | [15-baf.md](references/15-baf.md) |

| rict — gt summary tables: population, demographics, elections, compactness, splits | [16-rict.md](references/16-rict.md) |

| redistio — interactive Shiny plan drawing (draw()) and adjacency editor (adj_editor()) | [17-redistio.md](references/17-redistio.md) |

Key Data Structures

redist_map — an sf tibble with one row per precinct. Stores the adjacency graph, population column, number of districts, and population tolerance. Created by redist_map() or downloaded via alarm_50state_map(). Standard columns include pop, pop_black, pop_hisp, pop_asian, pop_white, pop_vap, pop_bvap, ndv (Democratic votes), nrv (Republican votes), and geometry.

redist_plans — a tibble with one row per district per plan (so nsims × ndists rows, plus reference plans). Stores district assignments in a hidden integer matrix; metrics are added as columns via mutate(). Access the plan matrix with get_plans_matrix().

adj — an S3 vector class representing an adjacency list. Each element is a zero-indexed integer vector of neighbors. Stored as the adj column in redist_map.

Population Tolerance Guidelines

| Map type | Typical pop_tol | Legal basis |

|----------|----------|-------------|

| Congressional | 0.005 (±0.5%) | Wesberry v. Sanders |

| State legislative | 0.05 (±10%) | Reynolds v. Sims |

| Local | Varies by state | State law |