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beta_shape_pnpi/tests/fitter/test_fit_engine.py
T

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Python

"""Tests for fitter.fit_engine."""
import numpy as np
from fitter.fit_engine import SpectrumFitter, FitConfig
from fitter.model import SpectrumModel
class TestFitConfig:
"""Test FitConfig defaults."""
def test_defaults(self) -> None:
config = FitConfig()
assert config.method == "trf"
assert config.max_nfev == 1000
assert config.loss == "linear"
class TestSpectrumFitter:
"""Test SpectrumFitter."""
def _make_fitter(self) -> "SpectrumFitter":
"""Create a simple fitter with synthetic data."""
# Create a simple linear model
def linear_model(
energies_keV: np.ndarray, norm: float, bg: float
) -> np.ndarray:
return norm * (1.0 - energies_keV / 100.0) + bg
# Synthetic data
energies = np.linspace(0.1, 99.9, 200)
counts = 10.0 * (1.0 - energies / 100.0) + 2.0
counts += np.random.RandomState(42).normal(0, 0.5, len(energies))
# Mock model
class MockModel:
def evaluate(
self, energies_keV: np.ndarray, norm: float, bg: float
) -> np.ndarray:
return linear_model(energies_keV, norm, bg)
model = MockModel()
fitter = SpectrumFitter(
model, energies, counts, exp_errors=np.ones_like(counts) * 0.5
)
return fitter
def test_fit_basic(self) -> None:
fitter = self._make_fitter()
result = fitter.fit(x0=[10.0, 2.0], param_names=["norm", "bg"])
assert result.success
assert result.n_points == 200
assert result.n_free == 2
assert result.chi2 > 0
assert result.chi2_per_dof > 0
assert len(result.parameters) == 2
def test_fit_with_bounds(self) -> None:
fitter = self._make_fitter()
result = fitter.fit(
x0=[10.0, 2.0],
bounds=([1.0, 0.0], [20.0, 10.0]),
)
assert result.success
def test_fit_returns_residuals(self) -> None:
fitter = self._make_fitter()
result = fitter.fit(x0=[10.0, 2.0])
assert len(result.residuals) == 200
assert len(result.model_values) == 200
def test_parameters_property(self) -> None:
fitter = self._make_fitter()
fitter.fit(x0=[10.0, 2.0])
params = fitter.parameters
assert len(params) == 2
def test_covariance_property(self) -> None:
fitter = self._make_fitter()
fitter.fit(x0=[10.0, 2.0])
cov = fitter.covariance
assert cov.shape == (2, 2)
def test_chi2_per_dof(self) -> None:
fitter = self._make_fitter()
result = fitter.fit(x0=[10.0, 2.0])
assert result.chi2_per_dof == result.chi2 / result.n_free
def test_p_value(self) -> None:
fitter = self._make_fitter()
result = fitter.fit(x0=[10.0, 2.0])
assert 0.0 <= result.p_value <= 1.0
def test_parameters_with_errors(self) -> None:
fitter = self._make_fitter()
result = fitter.fit(x0=[10.0, 2.0])
params = result.parameters_with_errors
assert len(params) == 2
for name, (val, err) in params.items():
assert isinstance(val, float)
assert isinstance(err, float)
assert err >= 0
def test_correlation_matrix(self) -> None:
fitter = self._make_fitter()
result = fitter.fit(x0=[10.0, 2.0])
corr = result.correlation_matrix
assert corr.shape == (2, 2)
# Diagonal should be 1
np.testing.assert_allclose(np.diag(corr), 1.0)
def test_summary(self) -> None:
fitter = self._make_fitter()
result = fitter.fit(x0=[10.0, 2.0], param_names=["norm", "bg"])
summary = result.summary(param_names=["norm", "bg"])
assert "norm" in summary
assert "bg" in summary
assert "Fit Results" in summary
def test_profile_likelihood(self) -> None:
fitter = self._make_fitter()
result = fitter.fit(x0=[10.0, 2.0])
param_vals, chi2_vals, norm_vals = result.profile_likelihood(0, n_points=10)
assert len(param_vals) == 10
assert len(chi2_vals) == 10
assert len(norm_vals) == 10
assert np.min(norm_vals) >= 0 # Normalized χ² should be >= 0
def test_confidence_interval(self) -> None:
fitter = self._make_fitter()
result = fitter.fit(x0=[10.0, 2.0])
ci = result.confidence_interval(0, confidence=0.95)
assert len(ci) == 2
assert ci[0] <= ci[1]
class TestSpectrumFitterWithRealModel:
"""Test SpectrumFitter with a real SpectrumModel."""
def test_fit_with_real_model(self) -> None:
from beta_spectrum import BetaSpectrum, SpectrumConfig
config = SpectrumConfig(
Z_parent=43,
Z_daughter=44,
A_number=99,
endpoint_MeV=0.294,
)
spectrum = BetaSpectrum.from_config(config)
model = SpectrumModel(spectrum)
# Generate synthetic data from the unconvolved model on a keV grid
energies_keV = np.linspace(1.0, 293.0, 200)
true_norm = 5.0
true_bg = 0.1
counts = model.evaluate(energies_keV, true_norm, true_bg)
counts = np.maximum(counts, 0) # Clip negatives
counts += np.random.RandomState(42).normal(
0, np.sqrt(np.maximum(counts, 1)), len(energies_keV)
)
counts = np.maximum(counts, 0)
fitter = SpectrumFitter(
model,
energies_keV,
counts,
exp_errors=np.sqrt(np.maximum(counts, 1)),
)
result = fitter.fit(x0=[1.0, 0.0], param_names=["norm", "bg"])
assert result.success
# Fit should complete without error
assert len(result.parameters) == 2