Module: Equalshares::FixedBudget

Defined in:
lib/equalshares/fixed_budget.rb

Overview

The fixed-budget Method of Equal Shares loop.

This unifies the two near-identical JS implementations (equalSharesFixedBudgetFractions and equalSharesFixedBudgetFloats in js/methodOfEqualSharesWorker.js) into a single loop driven by the numeric type of the values passed in:

- fractions mode: `cost` values and `b_total` are Rational  -> exact arithmetic
- floats mode:    `cost` values and `b_total` are Float      -> IEEE-754 arithmetic

The arithmetic (order and types) is kept bit-identical to the JS tool; the class below only reorganises the control flow into evaluate/charge steps.

Defined Under Namespace

Classes: Loop, Report

Class Method Summary collapse

Class Method Details

.run(voter_ids, project_ids, cost_source, approvers, budget_source, params, report_details: false, progress: nil) ⇒ Object

Dispatch on params.accuracy, preparing cost/budget in the right numeric type. cost_source maps project_id => original cost string; budget_source is the budget string. This mirrors JS where costs come from parseFloat, then (in the fractions path) get wrapped by new Fraction(...).



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# File 'lib/equalshares/fixed_budget.rb', line 22

def run(voter_ids, project_ids, cost_source, approvers, budget_source, params,
        report_details: false, progress: nil)
  case params.accuracy
  when "fractions"
    cost = cost_source.transform_values { |c| Election.rational_of(c) }
    b_total = Election.rational_of(budget_source)
  when "floats"
    cost = cost_source.transform_values { |c| Float(c) }
    b_total = Float(budget_source)
  else
    raise ComputeError, "Unknown accuracy parameter"
  end
  Loop.new(voter_ids, project_ids, cost, approvers, b_total, params,
           report_details: report_details, progress: progress).run
end