aug_spline_curve_simplify — Curve-control cubic-spline simplification

Group: Augmentation · C ABI: n4m_augmentation_spline_curve_simplification_*

Description

Simplify each spectrum via a cubic B-spline through a random control subset along the curve (nirs4all Spline_Curve_Simplification). Same behaviour as the x-axis variant, differing only in the uniform path’s np.unique handling.

Parameters

Name

Type

Default

spline_points

int

-1

uniform

bool

False

rng

Optional[PCG64]

None

seed

int

0

API and bindings

C ABI (ABI 2): n4m_augmentation_spline_curve_simplification_apply · n4m_augmentation_spline_curve_simplification_create · n4m_augmentation_spline_curve_simplification_destroy. Use the linked public header for the exact signature, configuration, and result handles.

Python (verified public re-export):

from n4m.augmentation.splines import SplineCurveSimplificationAugmenter

Source signature: SplineCurveSimplificationAugmenter().

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

No canonical paper defines this augmenter. It shares the internal interpolating B-spline engine with x simplification and exists for historical parity.

Mathematical principle

Reduce each spectrum to spline_points controls (default \(p/4\)), fit a not-a-knot cubic interpolant, and reconstruct the dense curve. Random mode is identical to x simplification; in uniform mode this variant additionally deduplicates rounded linspace indices.

Appropriate uses

Parity with the historical curve-simplification operator and sparse-curve stress tests.

Limits and validation

The distinction from x simplification is only the uniform-index deduplication rule. It is not a geometry-aware arc-length simplifier despite the name.

Implementation

Python role API n4m.augmentation.splines.SplineCurveSimplificationAugmenter; ABI 2 family n4m_augmentation_spline_curve_simplification_{create,apply,destroy}.

The ABI-2 implementation is the n4m_augmentation_spline_curve_simplification_* lifecycle in libn4m.

Sources and provenance

https://github.com/GBeurier/nirs4all-methods/blob/main/cpp/src/core/augmentation/splines/spline_curve_simplification.h

See also: methods index · interactive dashboard