Default eCPS reweighting to zero L0 penalty (#1124)

Author: MaxGhenis

changelog.d/zero-ecps-l0.changed.md

@@ -0,0 +1 @@
+Default enhanced CPS reweighting to no L0 sparsity penalty while preserving the configurable penalty for large calibration runs.

policyengine_us_data/datasets/cps/enhanced_cps.py

@@ -490,7 +490,7 @@ def reweight(
     targets_array,
     log_path="calibration_log.csv",
     epochs=500,
-    l0_lambda=2.6445e-07,
+    l0_lambda=0.0,
     init_mean=0.999,  # initial proportion with non-zero weights
     temperature=0.25,
     seed=1456,
@@ -534,7 +534,7 @@ def loss(weights):
         return rel_error_normalized.mean()
 
     logging.info(
-        f"Sparse optimization using seed {seed}, temp {temperature} "
+        f"Hard-concrete optimization using seed {seed}, temp {temperature} "
         + f"init_mean {init_mean}, l0_lambda {l0_lambda}"
     )
     set_seeds(seed)
@@ -600,7 +600,7 @@ def loss(weights):
         final_weights_sparse,
         loss_matrix,
         targets_array,
-        "L0 Sparse Solution",
+        "L0 Sparse Solution" if l0_lambda else "Unpenalized HardConcrete Solution",
         target_names=target_names,
     )
 

pyproject.toml

@@ -22,7 +22,7 @@ classifiers = [
     "Programming Language :: Python :: 3.14",
 ]
 dependencies = [
-    "policyengine-us==1.705.1",
+    "policyengine-us==1.705.15",
     # policyengine-core 3.26.1 is the current 3.26.x runtime and includes the fix for
     # PolicyEngine/policyengine-core#482 (user-set ETERNITY inputs lost
     # after _invalidate_all_caches) and is required by policyengine-us 1.682.1+.

tests/unit/test_enhanced_cps.py

@@ -1,3 +1,5 @@
+import inspect
+
 import numpy as np
 
 from policyengine_us_data.datasets.cps import enhanced_cps
@@ -9,6 +11,12 @@
 )
 
 
+def test_reweight_default_does_not_penalize_l0():
+    signature = inspect.signature(enhanced_cps.reweight)
+
+    assert signature.parameters["l0_lambda"].default == 0.0
+
+
 def test_get_base_aca_takeup_uses_stored_values():
     data = {
         "takes_up_aca_if_eligible": {