weac.parser.utils.layer_gradient module

Segment a windowed density profile into WEAC slab layers by gradient.

Companion to weac.parser.utils.layer_binning. Instead of grouping at a fixed thickness, this cuts the depth-ordered (surface -> ground) density series wherever the density gradient over a fixed 2.5 mm span exceeds a threshold, so ramps become a staircase of >= 1 mm layers while quiet stretches collapse into one homogeneous layer.

Why a fixed span

The native Loewe hop differs between parameterizations (CR2020 / P2015 / King), so an adjacent-sample slope is not comparable across methods. Measuring |drho/dz| over a constant 2.5 mm baseline (the P2015 window) makes a single threshold T meaningful for every parameterization.

Segmentation model

Each sample owns a “cell” (spacing to the next sample, last repeated), exactly as in the binning helper, so sum(layer.h) equals the summed cell thickness (times depth_scale). A sample whose fixed-span gradient is > T is a cut: it stands as its own layer (subject to the 1 mm floor). Consecutive <= T samples merge into one layer until the next cut. Thickness is depth_scale scaled; density is the cell-thickness-weighted mean over the run.

weac.parser.utils.layer_gradient.gradient_profile_to_layers(depth_mm, density_kg_m3, *, threshold_kg_m3_per_mm=12.0, span_mm=2.5, min_thickness_mm=1.0, depth_scale=1.0)[source]

Segment a density profile into WEAC slab layers by gradient (top-down).

Parameters:

  • depth_mm (ndarray) – Depth-ordered (surface -> ground) sample positions [mm].

  • density_kg_m3 (ndarray) – Density at each sample [kg m^-3]; same shape as depth_mm.

  • threshold_kg_m3_per_mm (float) – Cut threshold T. Samples whose fixed-span |drho/dz| exceeds T start their own layer; <= T samples merge. Default 12 (== 30 kg/m^3 across the 2.5 mm span).

  • span_mm (float) – Fixed baseline for the gradient [mm]; default 2.5.

  • min_thickness_mm (float) – Minimum layer thickness [mm]. Sub-floor segments are merged forward; a trailing remainder below the floor is folded into the previous layer.

  • depth_scale (float) – Plumb -> slope-normal factor applied to every h (cos(phi)); 1.0 leaves thicknesses unscaled.

Returns:

Layers ordered surface -> ground. sum(layer.h) equals the summed cell thickness times depth_scale.

Return type:

list[Layer]