pp_epo — External parameter orthogonalization (EPO)¶
Group: Feature extraction · C ABI: n4m_domain_adaptation_epo_*
Description¶
External Parameter Orthogonalisation.
Parameters¶
Name |
Type |
Default |
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API and bindings¶
C ABI (ABI 2): n4m_domain_adaptation_epo_create · n4m_domain_adaptation_epo_destroy · n4m_domain_adaptation_epo_fit · n4m_domain_adaptation_epo_inverse_transform · n4m_domain_adaptation_epo_is_fitted · n4m_domain_adaptation_epo_transform · n4m_domain_adaptation_epo_transform_with_d. Use the linked public header for the exact signature, configuration, and result handles.
Python (verified public re-export):
from n4m.domain_adaptation.orthogonalization import epo
Source signature: epo(X, d, scale: bool = True).
R: no current source-verified entry point was found for this catalog method.
MATLAB / Octave: no current source-verified entry point was found for this catalog method.
Explanations¶
Bibliographic source¶
Roger, Chauchard & Bellon-Maurel (2003), EPO-PLS external parameter orthogonalisation of PLS application to temperature-independent measurement of sugar content of intact fruits, Chemometrics and Intelligent Laboratory Systems 66, 191–204, https://doi.org/10.1016/S0169-7439(03)00051-0.
Mathematical principle¶
From nuisance-variation spectra, EPO estimates leading singular vectors \(P\) of the external-parameter subspace and projects data with \(I-PP^T\). Optional scaling is learned before the projection and reused at transform time.
Appropriate uses¶
Removing measured instrument, temperature, moisture, or batch variation before a calibration is fitted.
Limits and validation¶
The nuisance experiment must span unwanted variation without confounding analyte signal. Removing too many components deletes predictive information; EPO is stateful and must be fit within validation folds.
Implementation¶
n4m.domain_adaptation.orthogonalization.EPO wraps n4m_domain_adaptation_epo_*; SVD and projection are in preprocessing/orthogonalization/epo.c.
The ABI-2 implementation is the n4m_domain_adaptation_epo_* lifecycle in libn4m.
Sources and provenance¶
https://doi.org/10.1016/S0169-7439(03)00051-0; https://github.com/GBeurier/nirs4all-methods/blob/main/cpp/src/core/preprocessing/orthogonalization/epo.c
See also: methods index · interactive dashboard