xnicher 1.0.0

CRAN release

This is the first CRAN release of xnicher (formerly developed as nicher) for fitting ecological niche models with ellipsoidal environmental responses under the M hypothesis.

Model families

• optimize_niche() supports nine likelihood families: presence_only, weighted, ip_weighted, skew_normal, skew_normal_weighted, skew_t, skew_t_weighted, ncst, and ncst_weighted.
• Weighted families (weighted, ip_weighted, and their skew variants) use M-background environmental data through env_m.
• Non-symmetric families (skew_normal, skew_t, ncst, and their weighted variants) model asymmetric or heavy-tailed environmental responses.

Model comparison and validation

• S3 methods for logLik(), AIC(), BIC(), and nobs().
• compare_xnicher() for side-by-side model comparison.
• cv_xnicher() for k-fold and leave-one-out cross-validation of fitted xnicher objects.

Documentation

• Vignettes covering the getting-started workflow, cross-validation, all weighted/non-symmetric likelihood families, and the Rhipicephalus microplus example with iso-suitability and geographic maps.
• README examples cover the main model families.