R/vdg-package.R

In vdg: Variance Dispersion Graphs and Fraction of Design Space Plots

#' Variance Dispersion Graphs, Fraction-of-Design-Space Plots and Variants
#' 
#' This package provides functionality for producing variance dispersion graphs (VDGs), 
#' fraction-of-design (FDS) plots and related graphics for assessing the prediction variance
#' properties of experimental designs. Random sampling is used to assess the distribution of the 
#' prediction variance throughout the design region. Multiple design and/or model formulae
#' can be assessed at the same time. Graphics are produced by the \pkg{ggplot2} package.
#' 
#' @details The workhorse function in the package is \code{\link{spv}}, which takes lists of 
#' experimental designs and / or model formulae and produces samples throughout the design region
#' at which the prediction variance is evaluated. Depending on the type of input for the 
#' \code{design} and \code{formula} arguments, \code{\link{spv}} creates output objects of S3 classes
#' \code{spv}, \code{spvlist}, \code{spvforlist} or \code{spvlistforlist}. The graphical output are
#' obtained with the \code{\link{plot}} methods of these classes, and the \code{which} argument
#' can be used to control the type of plots produced. 
#' 
#' The design regions allowed for are typically spherical or cuboidal in nature, but the 
#' \code{keepfun} argument to \code{\link{spv}} can be used for rejection sampling. In this way 
#' nonstandard design regions can be allowed for. See also the \code{type} argument of \code{\link{spv}}.
#' The output from the \code{\link{plot}} methods for objects created by \code{\link{spv}} are 
#' typically named lists of graphical objects created by \pkg{ggplot2}. These are best stored in an 
#' object and recreated by printing the required plot. Storing such graphical objects also enables 
#' post-hoc manipulation of the plots, such as changing the background colour by using 
#' \pkg{ggplot2}'s \code{\link{theme}} function.
#' 
#' @seealso \code{\link{spv}}, \code{\link{plot.spv}}, and \code{vignette(topic = "vdg")}.
#' 
#' @name vdg-package
#' @aliases vdg-package vdg
#' @docType package
#' @author Pieter C. Schoonees <schoonees@gmail.com>
#' @references 
#' Pieter C. Schoonees, Niel J. le Roux, Roelof L.J. Coetzer (2016). Flexible Graphical Assessment of 
#' Experimental Designs in R: The vdg Package. \emph{Journal of Statistical Software}, 74(3), 1-22. 
#' \doi{10.18637/jss.v074.i03}.
#' @useDynLib vdg, fds, .registration = TRUE
#' @keywords package
#' @importFrom grDevices topo.colors
#' @importFrom methods is
#' @importFrom stats as.formula model.matrix na.omit predict quantile rnorm runif terms
#' @importFrom utils combn
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