eegr: Electrophysiological data analysis

#' EEGlocations
#'
#' Data frame of class \code{\link{sensorlocs}} containing 346 sensor locations
#' corresponding to the 10-5 electrode system for EEG.
#' 
#' A \code{\link{sensorlocs}} object is a \code{\link{data.frame}} containing sensor locations that can
#' be used in further analyses or display. In order to match R's plotting functions,
#' the coordinate system used in \code{eegr} models the head as a perfect sphere with a
#' radius of 1 and the origin in the middle of the head (0,0,0).
#' 
#' Within this system, Cartesian coordinates are defined along the following axes:
#' \describe{
#'   \item{x}{the X-axis points from the left (-) to right (+) pre-auricular points,
#'    i.e., positive values of x refer to sensors over the right hemisphere, whereas
#'    negative values of x refer to sensors over the left hemisphere.}
#'   \item{y}{the Y-axis points from the back of the head (inion, -) to the front
#'   (nasion, +), i.e., positive values of y refer to sensors over the anterior part
#'   of the brain, whereas negative values of y refer to sensors over the posterior
#'   part of the brain.}
#'   \item{z}{the Z-axis point from the bottom of the head (-) to the top (+) of body,
#'    i.e., positive values of z refer to sensors above the center of the head,
#'    whereas negative values of z refer to sensors below the center of the head.}
#' }
#' Angular coordinates are defined as follows:
#' \describe{
#'   \item{theta}{Theta is the angle angle between the Z-axis and the X/Y-plane;
#'   positive values indicate sensors over the right hemisphere; negative values
#'   over the left.}
#'   \item{phi}{Phi is the angle between the X- and Y-axes, with positive values
#'   indicating counterclockwise rotation and negative values clockwise.}
#' }
#' 
#' @references Oostenveld, R., Praamstra, P., 2001. The five percent electrode system for
#' high-resolution EEG and ERP measurements. Clin. Neurophysiol. 112, 713-719.
#' 
#' @author Geert van Boxtel <\email{G.J.M.vanBoxtel@@gmail.com}>
#' 
#' @examples
#' data(EEGlocations)

#' @format A data frame with 356 rows and 8 columns:
#' \describe{
#'   \item{label}{(\code{factor}) electrode label according to the 10-5 system, e.g., "AF1", "P3", etc.}
#'   \item{x}{(\code{numeric}) Cartesian x-axis (left-to-right) value}
#'   \item{y}{(\code{numeric}) Cartesian y-axis (back-to-front) value}
#'   \item{z}{(\code{numeric}) Cartesian z-axis (bottom-to-top) value}
#'   \item{x2d}{(\code{numeric}) x-axis value of orthogonal projection onto 2D plane}
#'   \item{y2d}{(\code{numeric}) y-axis value of orthogonal projection onto 2D plane}
#'   \item{theta}{(\code{numeric}) angle between 3D z-axis and x/y plane}
#'   \item{phi}{(\code{numeric}) angle between x- and y-axes}
#' }
"EEGlocations"