Package elections :: Module irv

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Module irv

source code

Implement all the functions for computing IRV margins and bounds.

Functions

number, dict, list, Node

irv_round(profile, rounds, rules=0)
Perform at most rounds rounds of IRV using rules.

source code

number, dict, list

irv(election, rules=0)
Perform IRV using rules and return the winner, vote counts, and elimination order. source code

number

irv_simple_lb(election, rules=1)
Compute and return an IRV margin lower bound using the elimination sets dictated by the rules.

source code

number

irv_margin(election, winner=None, elim_order=None, ub=None, trace=False, timeout=1e+75)
Compute the exact IRV margin of the election.

source code

number

irv_lb(election, eliminations=None, trace=False)
Compute and return an IRV margin lower bound and the optimal sequence of eliminations that gives it.

source code

number

irv_ub(election, rules=1, winner=None, elim_order=None, trace=False)
Compute and return an IRV margin upper bound.

source code

Variables
	BASE_IRV_RULES = `0`
	SF_RCV_RULES = `1`
	COMPLETE_IRV_RULES = `2`
	__package__ = `'elections'`

Function Details

irv_round(profile, rounds, rules=0)

source code

Perform at most rounds rounds of IRV using rules.

Parameters:

profile (Node) - The ballot profile.
rounds (number) - The maximum number of rounds to perform.
rules (enum) - The IRV rules to use for elimination.

Returns: number, dict, list, Node

Returns the winner, if any, the count of votes in each round, the list of elimination sets used, and the reduced tree after having eliminated candidates.

irv(election, rules=0)

source code

Perform IRV using rules and return the winner, vote counts, and elimination order.

Parameters:

election (Election) - The election.
rules (enum) - The rules to use.

Returns: number, dict, list

Returns the winner, the vote counts, and the elimination order.

irv_simple_lb(election, rules=1)

source code

Compute and return an IRV margin lower bound using the elimination sets dictated by the rules.

Parameters:

election (Election) - The election.
rules (enum) - The rules to use.

Returns: number

Returns the lower bound.

irv_margin(election, winner=None, elim_order=None, ub=None, trace=False, timeout=1e+75)

source code

Compute the exact IRV margin of the election.

Parameters:

election (Election) - The election.
winner (number) - The winner of the election. If None, it will be computed.
elim_order (list) - The elimination order. If None, it will be computed.
ub (number) - An upper bound on the margin. If None, it will be computed via irv_ub.
trace (boolean) - If True, print a trace of the computation.
timeout (number) - The amount of time to spend computing the margin.

Returns: number

Returns the IRV margin.

irv_lb(election, eliminations=None, trace=False)

source code

Compute and return an IRV margin lower bound and the optimal sequence of eliminations that gives it.

Parameters:

election (Election) - The election.
eliminations (list) - If not None, it is set to the optimal sequence of eliminations that gives the lower bound.
trace (boolean) - If True, then print out at trace of the computation.

Returns: number

Returns the lower bound.

irv_ub(election, rules=1, winner=None, elim_order=None, trace=False)

source code

Compute and return an IRV margin upper bound.

Parameters:

election (Election) - The election.
rules (enum) - The rules to use. Should probably not be changed.
trace (boolean) - If True, then print a trace of the computation.

Returns: number

Returns an upper bound on the margin.