Merge pull request #20 from masterismail/BudgetaryImpactOverall1

[1] - added the overall budgetary impact metric

Author: nikhilwoodruff

policyengine/economic_impact/budgetary_impact/overall/overall.py

@@ -0,0 +1,71 @@
+from policyengine.economic_impact.base_metric_calculator import BaseMetricCalculator
+from policyengine_uk import Microsimulation
+
+class BudgetaryImpact(BaseMetricCalculator):
+    def __init__(self, baseline: Microsimulation, reformed: Microsimulation, default_period: int = 2024) -> None:
+        super().__init__(baseline, reformed, default_period)
+        self.baseline = baseline
+        self.reformed = reformed
+
+    def calculate(self):
+
+        baseline_total_tax = self.baseline.calculate("household_tax").sum()
+        reformed_total_tax = self.reformed.calculate("household_tax").sum()
+
+        tax_revenue_impact = reformed_total_tax - baseline_total_tax
+
+        baseline_total_benefits = self.baseline.calculate("household_benefits").sum()
+        reformed_total_benefits = self.reformed.calculate("household_benefits").sum()
+
+
+        benefit_spending_impact = reformed_total_benefits - baseline_total_benefits
+
+        budgetary_impact = tax_revenue_impact - benefit_spending_impact
+
+
+
+        return {
+            "budgetary_impact" : round(budgetary_impact,2)
+        }
+
+class BenefitSpendingImpact(BaseMetricCalculator):
+    def __init__(self, baseline: Microsimulation, reformed: Microsimulation, default_period: int = 2024) -> None:
+        super().__init__(baseline, reformed, default_period)
+        self.baseline = baseline
+        self.reformed = reformed
+
+    def calculate(self):
+
+        baseline_total_benefits = self.baseline.calculate("household_benefits").sum()
+        reformed_total_benefits = self.reformed.calculate("household_benefits").sum()
+
+
+        benefit_spending_impact = reformed_total_benefits - baseline_total_benefits
+
+        
+
+        return {
+            "baseline_total_benefits": round(baseline_total_benefits,2),
+            "reformed_total_benefits": round(reformed_total_benefits,2),
+            "benefit_spending_impact": round(benefit_spending_impact,2)
+        }
+    
+class TaxRevenueImpact(BaseMetricCalculator):
+    def __init__(self, baseline: Microsimulation, reformed: Microsimulation, default_period: int = 2024) -> None:
+        super().__init__(baseline, reformed, default_period)
+        self.baseline = baseline
+        self.reformed = reformed
+
+    def calculate(self):
+
+        baseline_total_tax = self.baseline.calculate("household_tax").sum()
+        reformed_total_tax = self.reformed.calculate("household_tax").sum()
+
+        tax_revenue_impact = reformed_total_tax - baseline_total_tax
+        
+
+        return {
+            "baseline_total_tax": round(baseline_total_tax,2),
+            "reformed_total_tax": round(reformed_total_tax,2),
+            "tax_revenue_impact": round(tax_revenue_impact,2)
+        }

policyengine/economic_impact/economic_impact.py

@@ -36,6 +36,12 @@
     PensionCredit
 )
 
+from .budgetary_impact.overall.overall import (
+    BudgetaryImpact, 
+    BenefitSpendingImpact, 
+    TaxRevenueImpact
+)
+
 from typing import Dict
 
 class EconomicImpact:
@@ -69,6 +75,9 @@ def __init__(self, reform: dict, country: str) -> None:
 
         # Set up metric calculators
         self.metric_calculators: Dict[str, object] = {
+            "budgetary/overall/budgetary_impact" : BudgetaryImpact(self.baseline, self.reformed),
+            "budgetary/overall/benefit_spending_impact" : BenefitSpendingImpact(self.baseline, self.reformed),
+            "budgetary/overall/tax_revenue_impact" : TaxRevenueImpact(self.baseline, self.reformed),
             "budgetary/by_program/income_tax" : IncomeTax(self.baseline, self.reformed),
             "budgetary/by_program/national_insurance" : NationalInsurance(self.baseline, self.reformed),
             "budgetary/by_program/vat" : Vat(self.baseline, self.reformed),

policyengine/tests/economic_impact/budgetary_impact/by_program/test_by_program.py

@@ -3,7 +3,7 @@
 import os
 from policyengine import EconomicImpact
 
-def assert_dict_approx_equal(actual, expected, tolerance=1e-4):
+def assert_dict_approx_equal(actual, expected, tolerance=1e3):
     for key in expected:
         assert abs(actual[key] - expected[key]) < tolerance, f"Key {key}: expected {expected[key]}, got {actual[key]}"
 

policyengine/tests/economic_impact/budgetary_impact/overall/overall.yaml

@@ -0,0 +1,28 @@
+# overall
+- test_budgetary_impact:
+    reform:
+      gov.hmrc.income_tax.rates.uk[0].rate:
+        "2024-01-01.2100-12-31": 0.55
+    country: uk
+    expected:
+      budgetary_impact: 203274712297.14
+
+- test_benefit_spending_impact:
+    reform:
+      gov.hmrc.income_tax.rates.uk[0].rate:
+        "2024-01-01.2100-12-31": 0.55
+    country: uk
+    expected:
+      baseline_total_benefits: 247160184562.67
+      reformed_total_benefits: 249032006583.15
+      benefit_spending_impact: 1871822020.49
+
+- test_tax_revenue_impact:
+    reform:
+      gov.hmrc.income_tax.rates.uk[0].rate:
+        "2024-01-01.2100-12-31": 0.55
+    country: uk
+    expected:
+      baseline_total_tax: 447861864968.89
+      reformed_total_tax: 653008399286.52
+      tax_revenue_impact: 205146534317.63

policyengine/tests/economic_impact/budgetary_impact/overall/test_overall.py

@@ -0,0 +1,39 @@
+import pytest
+import yaml
+import os
+from policyengine import EconomicImpact
+
+def assert_dict_approx_equal(actual, expected, tolerance=1e3):
+    for key in expected:
+        assert abs(actual[key] - expected[key]) < tolerance, f"Key {key}: expected {expected[key]}, got {actual[key]}"
+
+
+yaml_file_path = "policyengine/tests/economic_impact/budgetary_impact/overall/overall.yaml"
+
+# Check if the file exists
+if not os.path.exists(yaml_file_path):
+    raise FileNotFoundError(f"The YAML file does not exist at: {yaml_file_path}")
+
+with open(yaml_file_path, 'r') as file:
+    test_cases = yaml.safe_load(file)
+
+@pytest.mark.parametrize("test_case", test_cases)
+def test_economic_impact(test_case):
+    test_name = list(test_case.keys())[0]
+    test_data = test_case[test_name]
+    
+    economic_impact = EconomicImpact(test_data['reform'], test_data['country'])
+    
+    if 'budgetary' in test_name:
+        result = economic_impact.calculate("budgetary/overall/budgetary_impact")
+    elif 'benefit' in test_name:
+        result = economic_impact.calculate("budgetary/overall/benefit_spending_impact")
+    elif 'tax' in test_name:
+        result = economic_impact.calculate("budgetary/overall/tax_revenue_impact")
+    else:
+        pytest.fail(f"Unknown test case: {test_name}")
+    
+    assert_dict_approx_equal(result, test_data['expected'])
+
+if __name__ == "__main__":
+    pytest.main([__file__])