Build a per-feature reference end-member for LMF calibration — build_reference

Computes mean (R_i) and standard deviation (sigma_R_i) for each ion in the collapsed LMF panel from reference samples within the calibration window. Called once per feature by add_lmf.

Usage

build_reference_endmember(reference_feature_uuid, cal_start, cal_end)

Arguments

reference_feature_uuid: UUID of the matched reference feature.
cal_start: Ideal calibration window start date.
cal_end: Ideal calibration window end date. Shifted backwards if reference data do not extend this far.

Value

NULL if no reference data are found. Otherwise a named list with elements:

stats: Tibble with columns ion, n_ref, R, sigma_R. Only ions with >= 3 observations are included.
window_start: Actual calibration window start used.
window_end: Actual calibration window end used.
n_samples: Number of sample events contributing.