Add default parameters to select statements

changelog_entry.yaml

@@ -0,0 +1,8 @@
+- bump: patch
+  changes:
+    fixed:
+      - Added default parameters to select statements for better performance and clarity (issue #1176)
+      - Updated select statements with dummy True conditions to use default parameter instead
+      - Set SINGLE as default for filing status select statements per issue #3334
+    changed:
+      - Consolidated Pell Grant calculation method variables by replacing pell_grant_calculation_method and pell_grant_uses_efc with pell_grant_uses_sai

policyengine_us/tests/tools/test_filing_status_utility.yaml

@@ -0,0 +1,55 @@
+# Test that select_filing_status_value works correctly with MD income tax
+- name: Test filing status utility with MD tax - single filer
+  period: 2024
+  input:
+    people:
+      person:
+        age: 30
+    tax_units:
+      tax_unit:
+        members: [person]
+        md_taxable_income: 50_000
+    households:
+      household:
+        members: [person]
+        state_code: MD
+  output:
+    md_income_tax_before_credits: 2_322.50
+
+- name: Test filing status utility with MD tax - joint filers
+  period: 2024
+  input:
+    people:
+      head:
+        age: 30
+      spouse:
+        age: 28
+    tax_units:
+      tax_unit:
+        members: [head, spouse]
+        md_taxable_income: 100_000
+    households:
+      household:
+        members: [head, spouse]
+        state_code: MD
+  output:
+    md_income_tax_before_credits: 4_697.50
+
+- name: Test filing status utility with MD tax - head of household
+  period: 2024
+  input:
+    people:
+      head:
+        age: 35
+      child:
+        age: 10
+    tax_units:
+      tax_unit:
+        members: [head, child]
+        md_taxable_income: 75_000
+    households:
+      household:
+        members: [head, child]
+        state_code: MD
+  output:
+    md_income_tax_before_credits: 3_510.00

policyengine_us/tools/general.py

@@ -84,3 +84,81 @@ def get_previous_threshold(
     return t[
         max_((t <= values.reshape((1, len(values))).T).sum(axis=1) - 1, 0)
     ]
+
+
+def select_filing_status_value(
+    filing_status: ArrayLike,
+    filing_status_values: dict,
+    input_value: ArrayLike = None,
+    **kwargs,
+) -> ArrayLike:
+    """
+    Select a value based on filing status, with SINGLE as the default.
+
+    This is a common pattern for selecting parameter values based on filing status.
+    According to IRS SOI data, SINGLE is the most common filing status.
+
+    Args:
+        filing_status: Array of filing status enum values
+        filing_status_values: Dict mapping filing status to values or functions
+        input_value: Optional input value to pass to functions (e.g., taxable income)
+
+    Returns:
+        Array of selected values based on filing status
+
+    Example:
+        # For parameter values
+        result = select_filing_status_value(
+            filing_status,
+            parameters.amount
+        )
+
+        # For calculated values (e.g., tax brackets)
+        result = select_filing_status_value(
+            filing_status,
+            parameters.rates,
+            taxable_income
+        )
+    """
+    statuses = filing_status.possible_values
+
+    # Helper function to get value
+    def get_value(fs_value):
+        if input_value is not None and hasattr(fs_value, "calc"):
+            # It's a rate schedule or similar
+            return fs_value.calc(input_value, **kwargs)
+        elif hasattr(fs_value, "__call__"):
+            # It's a callable
+            return (
+                fs_value(input_value, **kwargs)
+                if input_value is not None
+                else fs_value(**kwargs)
+            )
+        else:
+            # It's a simple value
+            return fs_value
+
+    # Build conditions and values, excluding SINGLE
+    conditions = []
+    values = []
+
+    # Check each filing status except SINGLE
+    for status_name in [
+        "JOINT",
+        "SEPARATE",
+        "HEAD_OF_HOUSEHOLD",
+        "SURVIVING_SPOUSE",
+    ]:
+        # Check if this enum value exists in this filing status enum
+        if hasattr(statuses, status_name):
+            status_enum = getattr(statuses, status_name)
+            if status_enum.name.lower() in filing_status_values:
+                conditions.append(filing_status == status_enum)
+                values.append(
+                    get_value(filing_status_values[status_enum.name.lower()])
+                )
+
+    # SINGLE is the default
+    default_value = get_value(filing_status_values["single"])
+
+    return select(conditions, values, default=default_value)

policyengine_us/variables/contrib/taxsim/taxsim_mstat.py

@@ -25,4 +25,5 @@ def formula(tax_unit, period, parameters):
                 6,
                 8,
             ],
+            default=1,  # SINGLE
         )

policyengine_us/variables/contrib/taxsim/taxsim_state.py

@@ -16,13 +16,12 @@ def formula(tax_unit, period, parameters):
                 state_code_str == "MA",
                 state_code_str == "NY",
                 state_code_str == "WA",
-                True,
             ],
             [
                 21,
                 22,
                 33,
                 48,
-                0,
             ],
+            default=0,
         )

policyengine_us/variables/gov/ed/pell_grant/efc/pell_grant_efc.py

@@ -28,4 +28,5 @@ def formula(person, period, parameters):
                 max_(0, head_contribution),
                 where(automatic_zero, 0, max_(0, head_contribution)),
             ],
+            default=0,
         )

policyengine_us/variables/gov/ed/pell_grant/head/pell_grant_head_contribution.py

@@ -16,7 +16,6 @@ def formula(person, period, parameters):
         assets = person("pell_grant_contribution_from_assets", period)
         adjusted_available_income = available_income + assets
         formula = person("pell_grant_formula", period)
-        uses_efc = person("pell_grant_uses_efc", period)
         uses_sai = person("pell_grant_uses_sai", period)
         p = parameters(period).gov.ed.pell_grant.head
         positive_head_contribution = p.marginal_rate.calc(
@@ -40,4 +39,4 @@ def formula(person, period, parameters):
         mask = dependents > 0
         amount_per_dependent[mask] = total[mask] / dependents[mask]
 
-        return select([uses_efc, uses_sai], [amount_per_dependent, total])
+        return where(uses_sai, total, amount_per_dependent)

policyengine_us/variables/gov/ed/pell_grant/pell_grant.py

@@ -14,10 +14,9 @@ def formula(person, period, parameters):
         efc = person("pell_grant_efc", period)
         sai = person("pell_grant_sai", period)
         eligibility = person("pell_grant_eligibility_type", period)
-        uses_efc = person("pell_grant_uses_efc", period)
         uses_sai = person("pell_grant_uses_sai", period)
         p = parameters(period).gov.ed.pell_grant
-        contribution = select([uses_efc, uses_sai], [efc, sai])
+        contribution = where(uses_sai, sai, efc)
         unbounded = coa - contribution
         amount = where(unbounded < p.amount.min, 0, unbounded)
         uncapped_efc_pell = amount * (
@@ -30,9 +29,8 @@ def formula(person, period, parameters):
                 eligibility == eligibility.possible_values.MINIMUM,
             ],
             [0, p.amount.max, amount],
+            default=0,
         )
-        uncapped = select(
-            [uses_efc, uses_sai], [uncapped_efc_pell, uncapped_sai_pell]
-        )
+        uncapped = where(uses_sai, uncapped_sai_pell, uncapped_efc_pell)
         max = min_(coa, p.amount.max)
         return min_(max, uncapped)

policyengine_us/variables/gov/ed/pell_grant/sai/eligibility_type/pell_grant_household_type.py

@@ -33,4 +33,5 @@ def formula(person, period, parameters):
                 PellGrantHouseholdType.INDEPENDENT_SINGLE,
                 PellGrantHouseholdType.INDEPENDENT_NOT_SINGLE,
             ],
+            default=PellGrantHouseholdType.INDEPENDENT_SINGLE,
         )

policyengine_us/variables/gov/ed/pell_grant/sai/pell_grant_uses_sai.py

@@ -5,8 +5,13 @@ class pell_grant_uses_sai(Variable):
     value_type = bool
     entity = Person
     definition_period = YEAR
-    label = "Pell Grant uses the student aid index"
+    label = "Pell Grant uses the Student Aid Index"
 
     def formula(person, period, parameters):
-        method = person.tax_unit("pell_grant_calculation_method", period)
-        return method == method.possible_values.SAI
+        return True
+
+    def formula_2024(person, period, parameters):
+        return True
+
+    def formula_2023(person, period, parameters):
+        return False

policyengine_us/variables/gov/hhs/ccdf/ccdf_age_group.py

@@ -34,4 +34,5 @@ def formula(person, period, parameters):
                 CCDFAgeGroup.PRESCHOOLER,
                 CCDFAgeGroup.SCHOOL_AGE,
             ],
+            default=CCDFAgeGroup.SCHOOL_AGE,
         )

policyengine_us/variables/gov/hhs/ccdf/ccdf_duration_of_care.py

@@ -27,12 +27,11 @@ def formula(person, period):
                 hours_per_week >= 30,
                 hours_per_day >= 6,
                 hours_per_day >= 3,
-                True,
             ],
             [
                 CCDFDurationOfCare.WEEKLY,
                 CCDFDurationOfCare.DAILY,
                 CCDFDurationOfCare.PART_DAY,
-                CCDFDurationOfCare.HOURLY,
             ],
+            default=CCDFDurationOfCare.HOURLY,
         )

policyengine_us/variables/gov/hhs/ccdf/ccdf_market_rate.py

@@ -30,5 +30,6 @@ def formula(person, period, parameters):
                 duration_of_care == durations_of_care.HOURLY,
             ],
             [1, days_per_week, days_per_week, hours_per_week],
+            default=0,
         )
         return rate_per_period * periods_per_week * WEEKS_IN_YEAR

policyengine_us/variables/gov/hhs/medicaid/eligibility/categories/medicaid_category.py

@@ -53,7 +53,7 @@ def formula(person, period, parameters):
             [
                 person(variable, period)
                 for variable in variable_to_category.keys()
-            ]
-            + [True],
-            list(variable_to_category.values()) + [MedicaidCategory.NONE],
+            ],
+            list(variable_to_category.values()),
+            default=MedicaidCategory.NONE,
         )

policyengine_us/variables/gov/irs/credits/elderly_and_disabled/section_22_income.py

@@ -27,14 +27,13 @@ def formula(tax_unit, period, parameters):
                 num_qualifying_individuals == 1,
                 num_qualifying_individuals == 2,
                 filing_status == filing_status.possible_values.SEPARATE,
-                True,
             ],
             [
                 elderly_disabled.amount.one_qualified,
                 elderly_disabled.amount.two_qualified,
                 elderly_disabled.amount.separate,
-                0,
             ],
+            default=0,
         )
 
         # Limitations on under-65s

policyengine_us/variables/gov/irs/income/taxable_income/adjusted_gross_income/irs_gross_income/social_security/tax_unit_taxable_social_security.py

@@ -65,11 +65,10 @@ def formula(tax_unit, period, parameters):
             [
                 under_first_threshold,
                 under_second_threshold,
-                True,
             ],
             [
                 0,
                 amount_if_under_second_threshold,
-                amount_if_over_second_threshold,
             ],
+            default=amount_if_over_second_threshold,
         )

policyengine_us/variables/gov/local/ny/nyc/tax/income/credits/household/nyc_household_credit.py

@@ -1,4 +1,5 @@
 from policyengine_us.model_api import *
+from policyengine_us.tools.general import select_filing_status_value
 
 
 class nyc_household_credit(Variable):
@@ -23,23 +24,25 @@ def formula(tax_unit, period, parameters):
         # Then get their number of people.
         tax_unit_size = tax_unit("tax_unit_size", period)
 
-        filing_statuses = filing_status.possible_values
-
-        return select(
-            [
-                filing_status == filing_statuses.SINGLE,
-                filing_status == filing_statuses.SEPARATE,
-            ],
-            [
-                # Single filers get a flat amount.
-                p.flat_amount.calc(federal_agi, right=True),
-                # Separate filers get an amount for each person in the tax
-                # unit, varying with AGI.
-                p.separate_per_dependent.calc(federal_agi, right=True)
-                * tax_unit_size,
-            ],
-            # Joint, head of household, and surviving spouse filers have a different
-            # amount per person, varying with AGI.
-            default=p.other_per_dependent.calc(federal_agi, right=True)
+        # Create a dictionary of values for each filing status
+        filing_status_values = {
+            "single": p.flat_amount.calc(federal_agi, right=True),
+            "separate": p.separate_per_dependent.calc(federal_agi, right=True)
             * tax_unit_size,
+            # Joint, head of household, and surviving spouse use the same formula
+            "joint": p.other_per_dependent.calc(federal_agi, right=True)
+            * tax_unit_size,
+            "head_of_household": p.other_per_dependent.calc(
+                federal_agi, right=True
+            )
+            * tax_unit_size,
+            "surviving_spouse": p.other_per_dependent.calc(
+                federal_agi, right=True
+            )
+            * tax_unit_size,
+        }
+
+        return select_filing_status_value(
+            filing_status,
+            filing_status_values,
         )