SYMMETRIC_ZONES

Python object: phenotypic.schema._symmetric_zones.SYMMETRIC_ZONES

Mask-based radial expansion measurements for colonies on solid media.

Summarises each colony’s radial growth through four scalars derived directly from the binary object mask: the inoculum core radius (shared with RADIAL_EXPANSION), the radius at which growth stops being angularly symmetric, and mean / maximum radial extent beyond the core.

Unlike RADIAL_EXPANSION, no skeletonization, branch tracing, or runner-outlier statistics are involved — all values are computed from per-annulus mask geometry and a circular-statistics angular resultant length. Intended for users who care about colony-level expansion and the symmetry of that expansion, not individual hyphae.

Category: SymZones

Column label	Description
SymZones_CoreRadius	Radius of the dense inoculum core, determined by PELT changepoint detection on the radial mask-density profile centered on the inoculum. Growth measurements are reported relative to this boundary.
SymZones_SymmetricRadius	Radial distance from the inoculum centroid at which colony growth ceases to be angularly uniform. Computed as the first radius past the core where the smoothed per-annulus circular mean resultant length of mask-boundary pixels exceeds the symmetry threshold. Equals the colony outer envelope when growth remains symmetric throughout.
SymZones_MeanExpansion	Mean distance of mask-boundary pixels from the inoculum centroid, measured from the core boundary outward. Captures the typical radial extent of growth past the inoculum, averaged over all angular directions.
SymZones_MaxExpansion	Maximum distance of any mask pixel from the inoculum centroid, measured from the core boundary outward. Captures the farthest extent of growth past the inoculum.
SymZones_CoreEndRadius	Mean radius of the inoculum core boundary derived from the per-angle bright/background ratio walk. Each of 360 1° angular sectors finds the outer edge of the contiguous core run (bright fraction >= tau_core); the reported value is the mean across sectors. Compare with CoreRadius (the global PELT changepoint) — close agreement indicates a well-formed core.
SymZones_DenseEndRadius	Mean outer radius of the dense branching zone, where mask-bright pixels dominate (bright fraction >= tau_sparse). Per-angle radii are capped at the SymmetricRadius and angularly median-smoothed before averaging.
SymZones_SparseEndRadius	Mean outer radius of the sparse branching zone (= colony envelope inside the symmetric growth front). Equals min(objmask outer envelope, SymmetricRadius) per angle, averaged across 360 sectors.
SymZones_CoreArea	Pixel^2 area of the inoculum core zone, integrated across the 360-sector polar polygon defined by the per-angle core radii.
SymZones_DenseArea	Pixel^2 area of the dense branching zone, the annular region between the per-angle core boundary and dense-branching boundary.
SymZones_SparseArea	Pixel^2 area of the sparse branching zone, the annular region between the per-angle dense boundary and the symmetric-envelope outer boundary.