R/qcd.r

In qcr: Quality Control Review

#-----------------------------------------------------------------------------#
#                                                                             #
#                  QUALITY CONTROL STATISTICS IN R                            #
#                                                                             #
#  An R package for statistical in-line quality control.                      #
#                                                                             #
#  Written by: Miguel A. Flores Sanchez                                       #
#              Professor of the Mathematics Department                        #
#              Escuela Politecnica Nacional, Ecuador                          #
#              miguel.flores@epn.edu.ec                                       #
#                                                                             #
#-----------------------------------------------------------------------------#

#
#  Main function to create a 'qcd' object
#



##' Quality Control Data
##' 
##' Create an object of class 'qcd' to perform statistical quality control.
##' This object may then be used to plot Shewhart charts, Multivariate Control Charts,
##' and more.
##' 
##' 
##' @aliases qcd 
##' @param data a matrix or data-frame which should contain data, index sample and,
##' optionally, covariate(s).
##' @param var.index a scalar with the column number corresponding to the observed data for
##' the variable (the variable quality).  Alternativelly can be a string with the
##' name of the quality variable.
##' @param sample.index a scalar with the column number corresponding to the index each
##' group (sample).
##' @param covar.index  optional. A scalar or numeric vector with the column number(s)
##' corresponding to the covariate(s). Alternativelly it can be a character vector with
##' the names of the covariates.
##' @param covar.names  optional. A string or vector of strings with names for the
##' covariate columns.  Only valid if there is more than one column of data. By
##' default, takes the names from the original object.
##' @param data.name  a string specifying the name of the variable which appears on the
##' plots. If not provided it is taken from the object given as data.
##' @param type.data  a string specifying the type of data.
##' @param sizes  optional. A value or a vector of values specifying the sample sizes
##' associated with each group. For continuous data the sample sizes are obtained counting the non-\code{NA} elements##' of the sample.index vector. For attribute variable the argument sizes is required.
##' @export

qcd <- function(data, var.index  =  1, sample.index  =  2,
                covar.index = NULL, covar.names = NULL,
                data.name = NULL,
                type.data  =  c("continuous", "atributte", "dependence"),
                sizes = NULL) 
  #.........................................................................
{
  
  if (!is.matrix(data) & !is.data.frame(data))
    stop("object must be a matrix or data.frame")
  
  type.data <- match.arg(type.data)
  
  
  if (type.data  ==  "atributte")
    if (is.null(sizes)) 
      stop("sample sizes must be given for a attribute variable")
  
  if (is.null(sizes)) sizes <- table(data[ ,sample.index])
  
  if (!is.null(covar.index)){
    result <- data[, c(var.index, sample.index, covar.index)]
  } else {
    result <- data[, c(var.index, sample.index)]  
  }
  
  result$sizes <- sizes
  
  
  if (!is.null(covar.index)) {
    if (!is.null(covar.names))
      names(result) <- c("x", "sample", covar.names,"sizes") 
    else 
      names(result)[1:2] <- c("x", "sample")
    names(result)[length(result)] <- c("sizes")
  } else 
    names(result) <- c("x", "sample","sizes")
  
  
  if (is.null(data.name))
    data.name <- deparse(substitute(data))
  
  attr(result, "data.name") <- data.name
  attr(result, "type.data") <- type.data
  
  oldClass(result) <- c("qcd", "data.frame")
  
  return(result)
} # qcd
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