R/AAA-Classes.R

In pierreroudier/inspectr: Storing, Manipulating and Analysis Spectroscopy and Associated Data in R

#' @include inspectr-package.R

#' @title Spectra* classes
#' @name Spectra-class
#' @aliases inspectr Spectra-class SpectraDataFrame-class as.data.frame.Spectra
#' as.data.frame.SpectraDataFrame as.data.frame.SpatialSpectra
#' names.SpectraDataFrame names<-.SpectraDataFrame print,Spectra-method
#' show,Spectra-method
#' @docType class
#' @description The inspectr package provides the user with S4 classes that have been
#' developped to store and manipulate spectroscopy data.
#' 
#' The \code{Spectra} class is storing the spectra matrix, along with the
#' wavelengths at which those have been measured, the units in whioch those
#' wavelengths are expressed, and a unique id for each sample in the
#' collection.
#' 
#' The \code{SpectraDataFrame} class is extending the \code{Spectra} class by
#' giving the opportunity to store attribute data along with the spectra - this
#' is mostly the case when we want to predict physical or chemical properties
#' from the spectra set.
#' 
#' The \code{SpatialSpectra} and \code{SpatialSpectraDataFrame} classes are
#' extending the \code{Spectra} and \code{SpectraDataFrame} classes using the
#' \code{SpatialPoints} class from package sp. This allows to store spatial
#' information on the dataset: coordinates, coordinate reference system,
#' bounding box, etc.
#' 
#' Common generic methods implemented for these classes include:
#' 
#' \code{summary}, \code{show}, \code{nrow}, \code{length}, \code{plot},
#' \code{[}, \code{[[}, \code{$}.
#' 
#' \code{SpatialPoints} methods from the sp package can be applied to
#' \code{SpatialSpectra} and \code{SpatialSpectraDataFrame} objects are they
#' inherit from this class.
#' 
#' @section Objects from the Class: Objects can be created by calls of the form
#' \code{new("Spectra", ...)}, with the constructor functions like
#' \code{Spectra(...)}, or with the helper functions such as \code{wl} and
#' \code{spectra}.
#' @author Pierre Roudier \email{pierre.roudier@@gmail.com}
#' @examples
#' 
#' showClass("Spectra")
#' showClass("SpectraDataFrame")
#' 
#' @rdname Spectra-class
#' @exportClass Spectra
setClass(
  Class="Spectra",
  representation=representation(
    wl = 'numeric',
    nir = 'matrix',
    id = 'data.frame',
    units = "character"
  ),
  prototype = prototype(
    wl = numeric(),
    nir = matrix(),
    id = data.frame(NA),
    units = as.character(NA)
  ),
  validity = function(object) {
    # if the wl are given as an integer vector they are translated into a numeric vector
    # for clarity (only one type to manage)
    if (is(object@wl, "integer"))
      object@wl <- as.numeric(object@wl)
    if (!inherits(object@wl, "numeric"))
      stop("wl should be of class integer or numeric")
    if ((nrow(object@id) > 0) & (nrow(object@nir) != nrow(object@id)))
      stop("number of individuals and number of rows in the spectra matrix don't match")
    if ((length(object@wl > 1) & (ncol(object@nir) != length(object@wl))))
      stop("number of columns in the spectra matrix and number of observed wavelengths don't match")
    if (length(unique(object@id[,1])) != nrow(object@id))
      stop("The ids of the samples need to be unique")
    return(TRUE)
  }
)

#' Class for spectra collections with associated attributes
#' @rdname Spectra-class
#' @slot wl object of class "\code{numeric}"; the wavelengths at which the spectra has been measured
#' @slot nir object of class "\code{matrix}"; the spectra, with as many columns as wavelengths, and as many rows as samples
#' @slot id object of class "\code{data.frame}" with one attribute; the identification strings for each sample in the collection
#' @slot units object of class "\code{character}"; units in which the wavelengths are expressed
#' @slot data object of class data.frame containing the attribute data
#' @author Pierre Roudier \email{pierre.roudier@@gmail.com}
#' @exportClass SpectraDataFrame
setClass(
  Class='SpectraDataFrame',
  representation=representation(
    "Spectra",
    data='data.frame'
  ),
  prototype=prototype(
    wl = numeric(),
    nir = matrix(),
    id = data.frame(NA),
    units = as.character(NA),
    data = data.frame()
  ),
  validity = function(object) {
    if (ncol(object@data) == 0)
      stop("data.frame is empty: use Spectra() to create spectra-only object")
    if (nrow(object@data) != nrow(object@nir))
      stop("number of rows in data.frame and spectra don't match")
    return(TRUE)
  }
)