The consecutive spacing-ratio of nucleosome arrays: high regularity from steric renewal, not level repulsion

Code, derived data and figures accompanying the paper "The consecutive spacing-ratio of nucleosome arrays: high regularity from steric renewal, not level repulsion." The unfold-free random-matrix level-spacing ratio ⟨r⟩ is applied to published base-pair-resolution chemical maps of nucleosome dyads in Saccharomyces cerevisiae (Brogaard et al. 2012) and Schizosaccharomyces pombe (Moyle-Heyrman et al. 2013). Both arrays give ⟨r⟩ ≈ 0.78–0.81, far above every random-matrix ensemble, but a permutation (shuffle) test shows this value is reproduced exactly by an i.i.d. renewal with the same linker-length distribution: the high ⟨r⟩ is a scalar, steric hard-core (Tonks-gas-like) property with no sequential level repulsion. The result is robust across confidence thresholds, nucleosome-free-region trimming and both species; superposition and random thinning each drive ⟨r⟩ back toward the Poisson value. The permutation test is shown to be a necessary control when applying ⟨r⟩ to genomic or spatial point patterns. The repository includes analysis scripts, derived spacing data and paper source. The raw chemical maps are third-party data (GEO GSE36063 and GSE46975) and are not redistributed here.