#' TARA ocean microbiome data
#'
#' The TARA Oceans expedition facilitated the study of plankton communities by 
#' providing oceans metagenomic data combined with environmental measures to the 
#' scientific community. This dataset focuses on 139 prokaryotic-enriched 
#' samples collected from 68 stations and spread across three depth layers: the 
#' surface (SRF), the deep chlorophyll maximum (DCM) layer and the mesopelagic 
#' (MES) zones. Samples were located in height different oceans or seas: Indian 
#' Ocean (IO), Mediterranean Sea (MS), North Atlantic Ocean (NAO), North Pacific
#' Ocean (NPO), Red Sea (RS), South Atlantic Ocean (SAO), South Pacific Ocean 
#' (SPO) and South Ocean (SO). Here, only a subset of the original data is 
#' provided (1\% of the 35,650 prokaryotic operational taxonomic units (OTUs) 
#' and of the 39,246 bacterial genes (NOGs) (selected at random).
#'
#' @usage data(TARAoceans)
#'
#' @format A list containing the following components:
#' \describe{
#'   \item{\code{phychem}}{data matrix with 139 rows and 22 columns. Each row 
#'     represents a sample and each column an environmental variable.}
#'   \item{\code{pro.phylo}}{data matrix with 139 rows (samples) and 356 columns
#'     (prokaryotic OTUs).}
#'   \item{\code{taxonomy}}{data matrix with 356 rows (prokaryotic OTUs) and 6 
#'     columns indicating the taxonomy of each OTU.}
#'   \item{\code{phylogenetic.tree}}{a phylo object (see package 'ape') 
#'     representing the prokaryotic OTUs phylogenetic tree.}
#'   \item{\code{pro.NOGs}}{data matrix with 139 rows (samples) and 638 columns 
#'     (NOGs).}
#'   \item{\code{sample}}{a list containing three following entries (all three 
#'     are character vectors): \code{name} (sample name), \code{ocean} (oceanic 
#'    region of the sample) and \code{depth} (sample depth).}
#' }
#' 
#' @source The raw data were downloaded from 
#' \url{http://ocean-microbiome.embl.de/companion.html}.
#' 
#' @keywords datasets
#' 
#' @references Sunagawa S., Coelho L.P., Chaffron S., Kultima J.R., Labadie K., 
#' Salazar F., Djahanschiri B., Zeller G., Mende D.R., Alberti A., 
#' Cornejo-Castillo F., Costea P.I., Cruaud C., d'Oviedo F., Engelen S., 
#' Ferrera I., Gasol J., Guidi L., Hildebrand F., Kokoszka F., Lepoivre C., 
#' Lima-Mendez G., Poulain J., Poulos B., Royo-Llonch M., Sarmento H., 
#' Vieira-Silva S., Dimier C., Picheral M., Searson S., Kandels-Lewis S., 
#' \emph{Tara} Oceans coordinators, Bowler C., de Vargas C., Gorsky G., 
#' Grimsley N., Hingamp P., Iudicone D., Jaillon O., Not F., Ogata H., Pesant 
#' S., Speich S., Stemmann L., Sullivan M., Weissenbach J., Wincker P., Karsenti 
#' E., Raes J., Acinas S. and Bork P. (2015). Structure and function of the 
#' global ocean microbiome. \emph{Science}, \bold{348}, 6237.
#' 
"TARAoceans"