PLNmodels: Poisson Lognormal Models

#' Mollusk data set
#'
#' This data set gives the abundance of 32 mollusk species in 163 samples.
#' For each sample, 4 additional covariates are known.
#'
#' @format A list with 2 two data frames:
#' \describe{
#'   \item{Abundance}{a 163 x 32 data frame of abundancies/counts (163 samples and 32 mollusk species)}
#'   \item{Covariate}{a 163 x 4 data frame of covariates:
#'   \describe{
#'     \item{site}{a factor with 8 levels indicating the sampling site}
#'     \item{season}{a factor with 4 levels indicating the season}
#'     \item{method}{a factor with 2 levels for the method of sampling - wood or string}
#'     \item{duration}{a numeric with 3 levels for the time of exposure in week}
#'   }
#'   }
#' }
#'
#' In order to prepare the data for using formula in multivariate analysis (multiple outputs and inputs), use [prepare_data()].
#' Original data set has been extracted from ade4.
#'
#' @seealso [prepare_data()]
#' @references Richardot-Coulet, M., Chessel D. and Bournaud M. (1986) Typological value of the benthos of old beds of a large river. Methodological approach. Archiv fùr Hydrobiologie, 107, 363–383.
#' @examples
#' data(mollusk)
#' mollusc <- prepare_data(mollusk$Abundance, mollusk$Covariate)
#' @source Data from Richardot-Coulet, Chessel and Bournaud.
"mollusk"