Class GerrymanderingDetector

java.lang.Object

org.episteme.social.politics.GerrymanderingDetector

public final class GerrymanderingDetector
extends Object

Provides algorithms to detect gerrymandering and partisan bias in electoral district maps. Includes implementations for Efficiency Gap, Mean-Median Difference, and Declination.

Since:

1.0

Version:

1.1

Author:

Silvere Martin-Michiellot, Gemini AI (Google DeepMind)

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static final record	GerrymanderingDetector.District	Data model for an individual electoral district.
static final record	GerrymanderingDetector.GerrymanderAnalysis	Comprehensive analysis result for a full district map.

Method Summary

Modifier and Type	Method	Description
static GerrymanderingDetector.GerrymanderAnalysis	analyze(List<GerrymanderingDetector.District> districts)	Performs a multi-metric analysis of a set of districts to detect partisan bias.
static double	polsbyPopperCompactness(List<double[]> polygon)	Calculates geometric compactness using the Polsby-Popper method.
static Map<Double,Double>	seatsVotesCurve(List<GerrymanderingDetector.District> districts, int points)	Simulates a seats-votes curve to visualize partisan lean.

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Details

analyze

public static GerrymanderingDetector.GerrymanderAnalysis analyze(List<GerrymanderingDetector.District> districts)

Performs a multi-metric analysis of a set of districts to detect partisan bias.

Parameters:

districts - the list of districts in the map

Returns:

a detailed analysis result

polsbyPopperCompactness

public static double polsbyPopperCompactness(List<double[]> polygon)

Calculates geometric compactness using the Polsby-Popper method. PP = 4π × Area / Perimeter²

Parameters:

polygon - list of vertices

Returns:

compactness ratio between 0 and 1

seatsVotesCurve

public static Map<Double,Double> seatsVotesCurve(List<GerrymanderingDetector.District> districts,
 int points)

Simulates a seats-votes curve to visualize partisan lean.

Parameters:

districts - base districts

points - number of points on the curve

Returns:

map of total vote share to resulting seat share