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Merge pull request #148 from PiaLJP/feature/correlated_combined_fit

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Feature/correlated combined fit
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Fabian Joswig 2023-02-03 17:05:36 +00:00 • committed by GitHub
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2 changed files with 132 additions and 30 deletions
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107
pyerrors/fits.py
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@ -705,9 +705,6 @@ def _standard_fit(x, y, func, silent=False, **kwargs):
def _combined_fit(x, y, func, silent=False, **kwargs):
if kwargs.get('correlated_fit') is True:
raise Exception("Correlated fit has not been implemented yet")
output = Fit_result()
output.fit_function = func
@ -735,6 +732,9 @@ def _combined_fit(x, y, func, silent=False, **kwargs):
if len(x_all.shape) > 2:
raise Exception('Unknown format for x values')
if np.any(np.asarray(dy_f) <= 0.0):
raise Exception('No y errors available, run the gamma method first.')
# number of fit parameters
n_parms_ls = []
for key in key_ls:
@ -766,6 +766,22 @@ def _combined_fit(x, y, func, silent=False, **kwargs):
else:
x0 = [0.1] * n_parms
if kwargs.get('correlated_fit') is True:
corr = covariance(y_all, correlation=True, **kwargs)
covdiag = np.diag(1 / np.asarray(dy_f))
condn = np.linalg.cond(corr)
if condn > 0.1 / np.finfo(float).eps:
raise Exception(f"Cannot invert correlation matrix as its condition number exceeds machine precision ({condn:1.2e})")
if condn > 1e13:
warnings.warn("Correlation matrix may be ill-conditioned, condition number: {%1.2e}" % (condn), RuntimeWarning)
chol = np.linalg.cholesky(corr)
chol_inv = scipy.linalg.solve_triangular(chol, covdiag, lower=True)
def chisqfunc_corr(p):
model = np.concatenate([np.array(func[key](p, np.asarray(x[key]))) for key in key_ls])
chisq = anp.sum(anp.dot(chol_inv, (y_f - model)) ** 2)
return chisq
def chisqfunc(p):
func_list = np.concatenate([[func[k]] * len(x[k]) for k in key_ls])
model = anp.array([func_list[i](p, x_all[i]) for i in range(len(x_all))])
@ -782,30 +798,46 @@ def _combined_fit(x, y, func, silent=False, **kwargs):
if 'tol' in kwargs:
tolerance = kwargs.get('tol')
fit_result = iminuit.minimize(chisqfunc, x0, tol=tolerance) # Stopping criterion 0.002 * tol * errordef
if kwargs.get('correlated_fit') is True:
fit_result = iminuit.minimize(chisqfunc_corr, fit_result.x, tol=tolerance)
output.iterations = fit_result.nfev
else:
tolerance = 1e-12
if 'tol' in kwargs:
tolerance = kwargs.get('tol')
fit_result = scipy.optimize.minimize(chisqfunc, x0, method=kwargs.get('method'), tol=tolerance)
if kwargs.get('correlated_fit') is True:
fit_result = scipy.optimize.minimize(chisqfunc_corr, fit_result.x, method=kwargs.get('method'), tol=tolerance)
output.iterations = fit_result.nit
chisquare = fit_result.fun
else:
if kwargs.get('correlated_fit') is True:
def chisqfunc_residuals_corr(p):
model = np.concatenate([np.array(func[key](p, np.asarray(x[key]))) for key in key_ls])
chisq = anp.dot(chol_inv, (y_f - model))
return chisq
def chisqfunc_residuals(p):
model = np.concatenate([np.array(func[key](p, np.asarray(x[key]))) for key in key_ls])
chisq = ((y_f - model) / dy_f)
return chisq
if 'tol' in kwargs:
print('tol cannot be set for Levenberg-Marquardt')
fit_result = scipy.optimize.least_squares(chisqfunc_residuals, x0, method='lm', ftol=1e-15, gtol=1e-15, xtol=1e-15)
if kwargs.get('correlated_fit') is True:
fit_result = scipy.optimize.least_squares(chisqfunc_residuals_corr, fit_result.x, method='lm', ftol=1e-15, gtol=1e-15, xtol=1e-15)
chisquare = np.sum(fit_result.fun ** 2)
assert np.isclose(chisquare, chisqfunc(fit_result.x), atol=1e-14)
output.iterations = fit_result.nfev
if kwargs.get('correlated_fit') is True:
assert np.isclose(chisquare, chisqfunc_corr(fit_result.x), atol=1e-14)
else:
assert np.isclose(chisquare, chisqfunc(fit_result.x), atol=1e-14)
output.message = fit_result.message
output.iterations = fit_result.nfev
if not fit_result.success:
raise Exception('The minimization procedure did not converge.')
@ -818,17 +850,12 @@ def _combined_fit(x, y, func, silent=False, **kwargs):
else:
output.chisquare_by_dof = float('nan')
output.message = fit_result.message
if not silent:
print(fit_result.message)
print('chisquare/d.o.f.:', output.chisquare_by_dof)
print('fit parameters', fit_result.x)
def chisqfunc_compact(d):
func_list = np.concatenate([[func[k]] * len(x[k]) for k in key_ls])
model = anp.array([func_list[i](d[:n_parms], x_all[i]) for i in range(len(x_all))])
chisq = anp.sum(((d[n_parms:] - model) / dy_f) ** 2)
return chisq
def prepare_hat_matrix():
hat_vector = []
for key in key_ls:
@ -838,24 +865,6 @@ def _combined_fit(x, y, func, silent=False, **kwargs):
hat_vector = [item for sublist in hat_vector for item in sublist]
return hat_vector
fitp = fit_result.x
if np.any(np.asarray(dy_f) <= 0.0):
raise Exception('No y errors available, run the gamma method first.')
try:
hess = hessian(chisqfunc)(fitp)
except TypeError:
raise Exception("It is required to use autograd.numpy instead of numpy within fit functions, see the documentation for details.") from None
jac_jac_y = hessian(chisqfunc_compact)(np.concatenate((fitp, y_f)))
# Compute hess^{-1} @ jac_jac_y[:n_parms + m, n_parms + m:] using LAPACK dgesv
try:
deriv_y = -scipy.linalg.solve(hess, jac_jac_y[:n_parms, n_parms:])
except np.linalg.LinAlgError:
raise Exception("Cannot invert hessian matrix.")
if kwargs.get('expected_chisquare') is True:
if kwargs.get('correlated_fit') is not True:
W = np.diag(1 / np.asarray(dy_f))
@ -868,12 +877,50 @@ def _combined_fit(x, y, func, silent=False, **kwargs):
if not silent:
print('chisquare/expected_chisquare:', output.chisquare_by_expected_chisquare)
fitp = fit_result.x
if np.any(np.asarray(dy_f) <= 0.0):
raise Exception('No y errors available, run the gamma method first.')
try:
if kwargs.get('correlated_fit') is True:
hess = hessian(chisqfunc_corr)(fitp)
else:
hess = hessian(chisqfunc)(fitp)
except TypeError:
raise Exception("It is required to use autograd.numpy instead of numpy within fit functions, see the documentation for details.") from None
if kwargs.get('correlated_fit') is True:
def chisqfunc_compact(d):
func_list = np.concatenate([[func[k]] * len(x[k]) for k in key_ls])
model = anp.array([func_list[i](d[:n_parms], x_all[i]) for i in range(len(x_all))])
chisq = anp.sum(anp.dot(chol_inv, (d[n_parms:] - model)) ** 2)
return chisq
else:
def chisqfunc_compact(d):
func_list = np.concatenate([[func[k]] * len(x[k]) for k in key_ls])
model = anp.array([func_list[i](d[:n_parms], x_all[i]) for i in range(len(x_all))])
chisq = anp.sum(((d[n_parms:] - model) / dy_f) ** 2)
return chisq
jac_jac_y = hessian(chisqfunc_compact)(np.concatenate((fitp, y_f)))
# Compute hess^{-1} @ jac_jac_y[:n_parms + m, n_parms + m:] using LAPACK dgesv
try:
deriv_y = -scipy.linalg.solve(hess, jac_jac_y[:n_parms, n_parms:])
except np.linalg.LinAlgError:
raise Exception("Cannot invert hessian matrix.")
result = []
for i in range(n_parms):
result.append(derived_observable(lambda x_all, **kwargs: (x_all[0] + np.finfo(np.float64).eps) / (y_all[0].value + np.finfo(np.float64).eps) * fitp[i], list(y_all), man_grad=list(deriv_y[i])))
output.fit_parameters = result
if kwargs.get('correlated_fit') is True:
n_cov = np.min(np.vectorize(lambda x_all: x_all.N)(y_all))
output.t2_p_value = 1 - scipy.stats.f.cdf((n_cov - output.dof) / (output.dof * (n_cov - 1)) * output.chisquare,
output.dof, n_cov - output.dof)
return output

55
tests/fits_test.py
View file

@ -703,6 +703,8 @@ def test_combined_fit_invalid_input():
yvals.append(pe.pseudo_Obs(x + np.random.normal(0.0, err), err, 'test1') + pe.pseudo_Obs(0, err / 100, 'test2', samples=87))
with pytest.raises(Exception):
pe.least_squares({'a':xvals}, {'b':yvals}, {'a':func_valid})
with pytest.raises(Exception):
pe.least_squares({'a':xvals}, {'a':yvals}, {'a':func_valid})
def test_combined_fit_no_autograd():
@ -833,6 +835,59 @@ def test_combined_fit_dictkeys_no_order():
assert(no_order_x_y[0] == order[0])
assert(no_order_x_y[1] == order[1])
def test_correlated_combined_fit_vs_correlated_standard_fit():
x_const = {'a':[0, 1, 2, 3, 4, 5, 6, 7, 8, 9], 'b':np.arange(10, 20)}
y_const = {'a':[pe.Obs([np.random.normal(1, val, 1000)], ['ensemble1'])
for val in [0.25, 0.3, 0.01, 0.2, 0.5, 1.3, 0.26, 0.4, 0.1, 1.0]],
'b':[pe.Obs([np.random.normal(1, val, 1000)], ['ensemble1'])
for val in [0.5, 1.12, 0.26, 0.25, 0.3, 0.01, 0.2, 1.0, 0.38, 0.1]]}
for key in y_const.keys():
[item.gamma_method() for item in y_const[key]]
y_const_ls = np.concatenate([np.array(o) for o in y_const.values()])
x_const_ls = np.arange(0, 20)
def func_const(a,x):
return 0 * x + a[0]
funcs_const = {"a": func_const,"b": func_const}
for method_kw in ['Levenberg-Marquardt', 'migrad', 'Powell', 'Nelder-Mead']:
res = []
res.append(pe.fits.least_squares(x_const, y_const, funcs_const, method = method_kw, correlated_fit=True))
res.append(pe.fits.least_squares(x_const_ls, y_const_ls, func_const, method = method_kw, correlated_fit=True))
[item.gamma_method for item in res]
assert np.isclose(0.0, (res[0].chisquare_by_dof - res[1].chisquare_by_dof), 1e-14, 1e-8)
assert np.isclose(0.0, (res[0].p_value - res[1].p_value), 1e-14, 1e-8)
assert np.isclose(0.0, (res[0].t2_p_value - res[1].t2_p_value), 1e-14, 1e-8)
assert (res[0][0] - res[1][0]).is_zero(atol=1e-8)
def test_combined_fit_hotelling_t():
xvals_b = np.arange(0,6)
xvals_a = np.arange(0,8)
def func_exp1(x):
return 0.3*np.exp(0.5*x)
def func_exp2(x):
return 0.3*np.exp(0.8*x)
def func_a(a,x):
return a[0]*anp.exp(a[1]*x)
def func_b(a,x):
return a[0]*anp.exp(a[2]*x)
funcs = {'a':func_a, 'b':func_b}
xs = {'a':xvals_a, 'b':xvals_b}
yobs_a = [pe.Obs([np.random.normal(item, item*1.5, 1000)],['ensemble1']) for item in func_exp1(xvals_a)]
yobs_b = [pe.Obs([np.random.normal(item, item*1.4, 1000)],['ensemble1']) for item in func_exp2(xvals_b)]
ys = {'a': yobs_a, 'b': yobs_b}
for key in funcs.keys():
[item.gamma_method() for item in ys[key]]
ft = pe.fits.least_squares(xs, ys, funcs, correlated_fit=True)
assert ft.t2_p_value >= ft.p_value
def fit_general(x, y, func, silent=False, **kwargs):
"""Performs a non-linear fit to y = func(x) and returns a list of Obs corresponding to the fit parameters.