pp_icoshift_align — Interval correlation optimized shifting (icoshift-style)¶
Group: Signal transforms · C ABI: n4m_transform_icoshift_align_*
Description¶
Interval correlation shifting with fixed-size intervals.
Parameters¶
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API and bindings¶
C ABI (ABI 2): n4m_transform_icoshift_align_create · n4m_transform_icoshift_align_destroy · n4m_transform_icoshift_align_fit · n4m_transform_icoshift_align_is_fitted · n4m_transform_icoshift_align_transform. Use the linked public header for the exact signature, configuration, and result handles.
Python (verified public re-export):
from n4m.transform.alignment import IcoshiftAlignment
Source signature: IcoshiftAlignment(reference = None, interval_size: int = 32, max_shift: int = 5).
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¶
Savorani, Tomasi & Engelsen (2010), icoshift: A versatile tool for the rapid alignment of 1D NMR spectra, Journal of Magnetic Resonance 202, 190–202, https://doi.org/10.1016/j.jmr.2009.11.012.
Mathematical principle¶
Each fixed interval is compared with the same reference interval over integer lags within max_shift; the lag maximizing the centered cross-product score is applied independently with edge replication. Output length and interval positions are retained.
Appropriate uses¶
Fast correction of piecewise-constant local channel shifts when peak order is stable.
Limits and validation¶
This is a fixed-interval, bounded-shift implementation rather than every option in the original icoshift software. Independent intervals may create seams and weak intervals yield unstable correlations.
Implementation¶
n4m.transform.alignment.IcoshiftAlignment uses n4m_transform_icoshift_align_*; interval search is implemented in cpp/src/c_api/c_api_advanced.cpp.
The ABI-2 implementation is the n4m_transform_icoshift_align_* lifecycle in libn4m.
Sources and provenance¶
https://doi.org/10.1016/j.jmr.2009.11.012; https://github.com/GBeurier/nirs4all-methods/blob/main/cpp/src/c_api/c_api_advanced.cpp
See also: methods index · interactive dashboard