itrak: Tools for processing eye-tracking data

#' Sample Time Series of Pupil Area
#'
#' A sample of 12 time series containing measurements of pupil area used by
#' the "pupil-data-vignette" to illustrate the use of \code{\link{itrak}}
#' functions.
#'
#' @format A data frame with 41652 rows and 6 variables:
#' \describe{
#'   \item{RECORDING_SESSION_LABEL}{index key for the eye-tracking session}
#'   \item{SAMPLE_INDEX}{index of consecutive integers indicating the
#'         temporal order of the observations of each trial in the session}
#'   \item{SAMPLE_MESSAGE}{field for "stamping" events in an eye-tracking
#'         session, such as the onset of a visual stimulus}
#'   \item{TIMESTAMP}{the computer clock time associated with each observation,
#'         in units of milliseconds}
#'   \item{LEFT_PUPIL_SIZE}{measured area of the left pupil}
#'   \item{RIGHT_PUPIL_SIZE}{measured area of the right pupil, empty here
#'         as the right pupil was not measured}}
#'
#' @source Data were collected in the Mood Disorders Laboratory at the
#' University of Texas at Austin using an EyeLink 1000 Plus, sampling pupil area
#' from a single eye at a frequency of 500 Hz. The data shown here are a
#' selection of 9 experimental trials and 3 drift-correction calibrations
#' from a longer experimental session consisting of 90 trials, each involving
#' a 2-second baseline period of viewing a gray screen followed by 6 seconds
#' of viewing an image from the International Affective Picture System (IAPS).

"pupil_data"