Files
aare/python/tests/test_Fit.py
T
Erik FröjdhandClaude Fable 5.1 a211a3e8e2 Add Minimizer::VarPro, a variable projection minimizer
Every bundled model now declares the parameters it is linear in
(linear_par, basis_and_grad) and, except the polynomials, a vectorisable
bulk basis pass (basis_columns) built on the new model::fast_exp. The
Levenberg-Marquardt iteration is factored into a shared DampedGaussNewton
driver with unchanged results; VarPro solves the linear parameters exactly
at every trial point and iterates over the nonlinear ones, rejecting
degenerate trial points and polishing the converged point with one
undamped step. Limits on linear parameters, pixels that do not converge
and models without the separable structure fall back to
LevenbergMarquardt. Parameter errors are the same Gauss-Newton estimates.
The [fit] tests run VarPro through every configuration and check the
separable structure of each model against its derivatives.

Measured on an M1 Max, single thread: FallingScurve population 5.5 us per
fit against 11.7 us with LevenbergMarquardt, and 2 wrong minima in 4096
pixels against 30; Gaussian 3.3 vs 4.3 us; GaussianChargeSharingKb 33 vs
49 us; Pol2 0.34 vs 1.52 us. Migrad stays the default.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
2026-09-25 21:36:53 +02:00

242 lines
8.1 KiB
Python

# SPDX-License-Identifier: MPL-2.0
import numpy as np
import pytest
import aare
MINIMIZERS = [
aare.Minimizer.Migrad,
aare.Minimizer.Fumili,
aare.Minimizer.LevenbergMarquardt,
aare.Minimizer.VarPro,
]
def gaussian(x, A, mu, sigma):
return A * np.exp(-0.5 * ((x - mu) / sigma) ** 2)
def uses_minuit2(minimizer):
return minimizer not in (
aare.Minimizer.LevenbergMarquardt,
aare.Minimizer.VarPro,
)
@pytest.fixture(params=MINIMIZERS, ids=lambda m: m.name)
def minimizer(request):
return request.param
@pytest.fixture
def gaussian_data():
x = np.linspace(-6.0, 6.0, 61)
y = gaussian(x, 120.0, 0.8, 1.3)
y_err = np.ones_like(y)
return x, y, y_err
def test_gaussian_model_evaluates_and_fits_data(minimizer):
x = np.linspace(-5.0, 5.0, 51)
expected = np.array([20.0, 0.5, 1.2])
model = aare.Gaussian(minimizer=minimizer)
y = model(x, expected)
result = model.fit(x, y)
np.testing.assert_allclose(result["par"], expected, atol=2e-3)
def test_minimizer_can_be_selected():
assert aare.Gaussian().minimizer == aare.Minimizer.Migrad
assert set(aare.Minimizer.__members__) == {
"Migrad",
"Fumili",
"LevenbergMarquardt",
"VarPro",
}
for minimizer in MINIMIZERS:
assert aare.Gaussian(minimizer=minimizer).minimizer == minimizer
model = aare.Gaussian()
model.minimizer = aare.Minimizer.LevenbergMarquardt
assert model.minimizer == aare.Minimizer.LevenbergMarquardt
def test_fit_returns_errors_and_chi2(gaussian_data, minimizer):
x, y, y_err = gaussian_data
model = aare.Gaussian(compute_errors=True, minimizer=minimizer)
result = model.fit(x, y, y_err)
assert set(result) == {"par", "par_err", "chi2"}
assert result["par"].shape == (3,)
assert result["par_err"].shape == (3,)
assert result["chi2"].shape == (1,)
np.testing.assert_allclose(result["par"], [120.0, 0.8, 1.3], rtol=1e-4)
np.testing.assert_allclose(
result["par_err"], [0.361, 0.00451, 0.00451], rtol=2e-2
)
assert result["chi2"][0] == pytest.approx(0.0, abs=1e-3)
without_errors = aare.fit(aare.Gaussian(minimizer=minimizer), x, y)
assert set(without_errors) == {"par", "chi2"}
def test_pol1_weighted_errors_match_analytic_formula(minimizer):
x = np.arange(20, dtype=float)
y = 2.0 + 0.5 * x
y_err = 1.0 + 0.1 * x
w = 1.0 / y_err**2
S, Sx, Sxx = w.sum(), (w * x).sum(), (w * x * x).sum()
delta = S * Sxx - Sx * Sx
result = aare.Pol1(compute_errors=True, minimizer=minimizer).fit(x, y, y_err)
np.testing.assert_allclose(result["par"], [2.0, 0.5], rtol=1e-6)
np.testing.assert_allclose(
result["par_err"],
[np.sqrt(Sxx / delta), np.sqrt(S / delta)],
rtol=1e-6,
)
def test_fixed_parameter_reports_zero_error(gaussian_data, minimizer):
x, y, y_err = gaussian_data
model = aare.Gaussian(compute_errors=True, minimizer=minimizer)
model.FixParameter("sigma", 1.5)
result = model.fit(x, y, y_err)
assert result["par"][2] == 1.5
assert result["par_err"][2] == 0.0
assert result["par"][0] == pytest.approx(111.15, rel=1e-3)
assert result["chi2"][0] == pytest.approx(1684.25, rel=1e-3)
model.ReleaseParameter("sigma")
result = model.fit(x, y, y_err)
assert result["par"][2] == pytest.approx(1.3, rel=1e-4)
def test_active_limit_ends_on_the_limit(gaussian_data, minimizer):
x, y, y_err = gaussian_data
model = aare.Gaussian(compute_errors=True, minimizer=minimizer)
model.SetParLimits("mu", -5.0, 0.5)
result = model.fit(x, y, y_err)
margin = 1e-6 if uses_minuit2(minimizer) else 1e-9
assert result["par"][1] == pytest.approx(0.5, abs=margin)
assert result["par_err"][1] == 0.0
assert result["par"][0] == pytest.approx(116.88, rel=1e-3)
assert result["chi2"][0] == pytest.approx(4301.95, rel=1e-3)
inactive = aare.Gaussian(minimizer=minimizer)
inactive.SetParLimits(1, -5.0, 5.0)
np.testing.assert_allclose(
inactive.fit(x, y)["par"], [120.0, 0.8, 1.3], rtol=1e-4
)
def test_user_start_value(gaussian_data, minimizer):
x, y, _ = gaussian_data
model = aare.Gaussian(minimizer=minimizer)
model.SetParameter("mu", 0.0)
np.testing.assert_allclose(model.fit(x, y)["par"], [120.0, 0.8, 1.3], rtol=1e-4)
def test_max_calls_failure_returns_zeros(gaussian_data, minimizer):
x, y, y_err = gaussian_data
model = aare.Gaussian(max_calls=3, compute_errors=True, minimizer=minimizer)
# start far from the minimum so that no minimizer converges in 3 calls
model.SetParameter("mu", -3.0)
model.SetParameter("sigma", 3.0)
result = model.fit(x, y, y_err)
assert np.all(result["par"] == 0.0)
assert np.all(result["par_err"] == 0.0)
assert np.all(result["chi2"] == 0.0)
def test_strategy_is_ignored_by_levenberg_marquardt(gaussian_data):
x, y, _ = gaussian_data
lm = aare.Minimizer.LevenbergMarquardt
a = aare.Gaussian(strategy=0, minimizer=lm).fit(x, y)
b = aare.Gaussian(strategy=1, minimizer=lm).fit(x, y)
np.testing.assert_array_equal(a["par"], b["par"])
def test_invalid_parameter_access_raises():
model = aare.Gaussian()
assert model.par_names == ["A", "mu", "sigma"]
assert model.n_par == 3
with pytest.raises(RuntimeError):
model.SetParameter("nope", 1.0)
with pytest.raises(IndexError):
model.SetParameter(3, 1.0)
with pytest.raises(RuntimeError):
model.SetParLimits("mu", 1.0, 1.0)
@pytest.mark.parametrize("cls", [aare.RisingScurve, aare.FallingScurve])
def test_scurve_fit(cls, minimizer):
truth = np.array([10.0, 0.1, 50.0, 3.0, 1000.0, 2.0])
x = np.linspace(0.0, 100.0, 100)
model = cls(max_calls=500, compute_errors=True, minimizer=minimizer)
y = model(x, truth)
result = model.fit(x, y, np.ones_like(y))
np.testing.assert_allclose(result["par"], truth, rtol=1e-3)
assert np.all(result["par_err"] > 0.0)
@pytest.mark.parametrize("with_errors", [False, True])
@pytest.mark.parametrize("weighted", [False, True])
def test_fit_3d_matches_fit_1d(with_errors, weighted, minimizer):
x = np.linspace(-6.0, 6.0, 61)
rows, cols = 4, 3
y = np.empty((rows, cols, x.size))
for r in range(rows):
for c in range(cols):
y[r, c] = gaussian(x, 80.0 + 10.0 * r, -0.6 + 0.3 * c, 0.9 + 0.1 * r)
y_err = np.ones_like(y) if weighted else None
model = aare.Gaussian(compute_errors=with_errors, minimizer=minimizer)
cube = model.fit(x, y, y_err, n_threads=3)
expected_keys = {"par", "par_err", "chi2"} if with_errors else {"par", "chi2"}
assert set(cube) == expected_keys
assert cube["par"].shape == (rows, cols, 3)
assert cube["chi2"].shape == (rows, cols)
if with_errors:
assert cube["par_err"].shape == (rows, cols, 3)
for r in range(rows):
for c in range(cols):
single = model.fit(x, y[r, c], None if y_err is None else y_err[r, c])
np.testing.assert_allclose(cube["par"][r, c], single["par"], rtol=1e-10)
assert cube["chi2"][r, c] == pytest.approx(single["chi2"][0], abs=1e-10)
if with_errors:
np.testing.assert_allclose(
cube["par_err"][r, c], single["par_err"], rtol=1e-10
)
np.testing.assert_allclose(cube["par"][3, 2], [110.0, 0.0, 1.2], rtol=1e-4, atol=1e-6)
def test_all_minimizers_agree_on_3d_data_with_errors():
x = np.linspace(-5.0, 5.0, 51)
expected = np.array([20.0, 0.5, 1.2])
single = aare.Gaussian()(x, expected)
y = np.tile(single, (2, 3, 1))
y_err = np.ones_like(y)
results = {
minimizer: aare.Gaussian(compute_errors=True, minimizer=minimizer).fit(
x, y, y_err, n_threads=2
)
for minimizer in MINIMIZERS
}
reference = results[aare.Minimizer.Migrad]
for minimizer, result in results.items():
assert result["par"].shape == (2, 3, 3)
assert result["par_err"].shape == (2, 3, 3)
np.testing.assert_allclose(result["par"], np.broadcast_to(expected, (2, 3, 3)), atol=2e-3)
np.testing.assert_allclose(result["chi2"], 0.0, atol=1e-3)
np.testing.assert_allclose(result["par_err"], reference["par_err"], rtol=2e-2)