The Poisson-lognormal model and variants can be used for a variety of multivariate problems when count data are at play, including principal component analysis for count data (Chiquet, Mariadassou and Robin, 2018 <doi:10.1214/18-AOAS1177>), discriminant analysis and network inference (Chiquet, Mariadassou and Robin, 2018 <http://proceedings.mlr.press/v97/chiquet19a.html>). Implements variational algorithms to fit such models accompanied with a set of functions for visualization and diagnostic.