ewing: Ewing's Quantitative Population Ethology

#' substrate data for host-parasite movement
#' 
#' The substrate.species tables (\code{substrate.host}, etc.) describe movement
#' rates on the substrate. The substrate.substrate object
#' (\code{substrate.substrate}) describes connectivity of substrate units.
#' Names of species and substrate(s) are established in
#' \code{organism.features} and internalized via \code{init.simulation}.
#' 
#' The substrate classes are defined implicitly in the substrate.species
#' interaction tables, and could be different for different species on the same
#' substrate. These substrate classes are associated with the possible
#' substrate positions (7 in this simulation, 4 on fruit, 2 on leaf and 1 on
#' twig).
#' 
#' Movement of individuals is rather primitive in this invocation, and is not
#' fully implemented. The \code{find} and \code{move} are placeholders for
#' future improvements. Basically the intent is that teh risk for moving from a
#' position on the substrate is proportional to \code{move}, while the risk of
#' moving to a new position is proportional to \code{find}. As set, fruit is
#' more preferable than leaf, which is preferred to twig, for all species.
#' [These columns are not in fact used for current simulations.] Connectivity
#' of positions is determined by substrate.substrate, which contains 0s and 1s,
#' with positions directly connected (1) or not (0).
#' 
#' @name substrate.host
#' @aliases substrate.host substrate.parasite substrate.substrate
#' @format The substrate.species objects have the following columns:
#' \describe{
#'  \item{substrate}{class of substrate (fruit, twig or leaf)}
#'  \item{side}{side of substrate}
#'  \item{init}{weights for initialization of simulation}
#'  \item{find}{risk species finds this new position on substrate}
#'  \item{move}{risk species moves from this position on substrate}
#'  \item{fruit}{first substrate class (substrate fruit)}
#'  \item{twig}{second substrate class (twig connecting fruit to branch)}
#'  \item{leaf}{third substrate class (leaf on twig)}
#' }
#' 
#' The row names of substrate.species objects coincide with the row and column
#' names of substrate.substrate. Notice that for this simulation, there are
#' four sides to each fruit (1,2,3,4) and two sides to each leaf (top,bottom),
#' but only one side to a twig.
#' \describe{
#'  \item{fr1}{fruit side 1}
#'  \item{fr2}{fruit side 2}
#'  \item{fr3}{fruit side 3}
#'  \item{fr4}{fruit side 4}
#'  \item{twig}{twig}
#'  \item{lftop}{leaf top}
#'  \item{lfbot}{leaf bottom}
#' }
#' @seealso \code{\link{init.simulation}},\code{\link{organism.features}}
#' @references \url{www.stat.wisc.edu/~yandell/ewing}
#' @keywords datasets
#' @examples
#' 
#' data(substrate.host)
#' data(substrate.parasite)
#' data(substrate.substrate)
#' 
NULL