Graphs and Covariance for Landscape Genetics

Shared, dependency-light primitives for landscape-genetic network methods: a lightweight deme/landscape graph (vertex coordinates and an undirected edge list) with constructors from coordinates; genetic covariance and distance from biallelic or multiallelic data (the normalized-dosage covariance of Yang et al. (2010) , and the multivariate covariance of Dyer and Nason (2004) built by the Gower (1966) double-centering); pairwise F_ST by the estimator of Bhatia et al. (2013) ; and antisymmetric per-edge directional covariate builders (the gradient of a scalar potential, and the projection of a vector flow field). Used by 'terradish' (symmetric resistance).