R/pattL.fit.R

In prefmod: Utilities to Fit Paired Comparison Models for Preferences

pattL.fit<-function(obj, nitems,formel=~1,elim=~1,resptype="rating",
         obj.names=NULL, undec=TRUE, ia=FALSE, NItest=FALSE, pr.it=FALSE)
{

    call<-match.call()
    ENV<-new.env()
    ENV$pr.it<-pr.it

    ENV$resptype<-"rating"

    nobj<-nitems
    opt<-options()
    options("warn"=-1)

#######################################
  if(is.character(obj)){                    ## datafilename supplied
        datafile    <-  obj
        if(file.access(datafile, mode=0) == 0){
           dat<-as.matrix(read.table(datafile,header=TRUE))  # datafile
        } else {
           stop("\ninput data file does not exist!\n")
        }
   } else if(is.data.frame(obj)){            ## data frame supplied
        dat<-as.matrix(obj)                                  # dataframe
        dat<-apply(dat,2,as.numeric)
   } else {
        stop("first argument must be either datafilename or dataframe")
   }
   varnames<-colnames(dat)
   if (ncol(dat)>nobj) {
        #covnames<-varnames[(nobj+1):ncol(dat)]
        #covs<-as.data.frame(dat[,(nobj+1):ncol(dat)])
        ## instead of the above rh 2011-05-13
        formel.names<-attr(terms(as.formula(formel)),"term.labels")
        formel.names<-unique(unlist(strsplit(formel.names,":"))) # 2011-08-31 remove interaction terms
        elim.names<-attr(terms(as.formula(elim)),"term.labels")
        elim.names<-unique(unlist(strsplit(elim.names,":")))     # 2011-08-31 remove interaction terms
        covnames<-unique(c(formel.names,elim.names))
        covs<-as.data.frame(dat[,covnames])
   } else {
        covs<-NULL
   }

   # for ratings: at least two items not NA
   idx<-apply(dat[,1:nobj],1,function(x) sum(!is.na(x))>1)
   dat<-dat[idx,]
   dat<-as.data.frame(dat[,1:nobj])

   if(!is.null(covs)){
        covs<-as.data.frame(covs[idx,])
        colnames(covs)<-covnames
        NAs<-which(!complete.cases(covs))                  # check for NA
        if (length(NAs)>0){
             cat("\tsubject covariates: NAs in lines",NAs," - removed from data\n")
             notNAs<-which(complete.cases(covs))
             dat<-dat[notNAs,]
             # covs<-covs[notNAs,] ## replaced 20-08-09
             covs<-covs[notNAs,,drop=FALSE]
        }
   }

#######################################

    ## option for obj.names added
    if (is.null(obj.names))
      ENV$obj.names<-varnames[1:nobj]
    else
      ENV$obj.names<-obj.names[1:nobj]

    if(NItest)
      if(!any(is.na(dat)))
         stop("Test for ignorable missing cannot be performed - no NA values!")

    datrng<-range(dat,na.rm=TRUE)

    # reduce datamatrix and genenerate and reduce patternmatrix
    dat<-as.data.frame(diffsred(dat,nobj))
    ENV$Y <- Lpatternmat(datrng,nobj) # pattern matrix reduced

    # only global undecided
    if(undec)
      ENV$U <- apply(ENV$Y,1,function(x) sum(x==0))
    ENV$undec<-undec

    ENV$NItest<-NItest
    if(ENV$NItest) {
          if(formel!="~1" || elim != "~1"){
          covs<-NULL
          formel<-~1
          elim<-~1
          cat("\ncurrently no covariates fitted if NItest==TRUE !!\n")
       }
    }

    ENV$ia<-ia
    if (ia) {
       depL<-dependencies(nobj,ENV$Y)
       ENV$XI<-depL$d
       ilabels<-depL$label.intpars
       npars.ia<-nobj*(nobj-1)*(nobj-2)/2
    } else {
       ilabels<-NULL
       npars.ia<-0
    }

    X<- ENV$Y %*% pcdesign(nobj)
    X<- -X[,-nobj]                          # basic design matrix

    cList<-splitCovs(dat,covs,formel,elim,ENV)   # split data according to subject covariates
    partsList<-gen.partsList(nobj,cList,ENV)     # generate list for all subj covariate x miss values groups
    rm(cList)



    npar <- (nobj-1) * ENV$ncovpar + ENV$undec + npars.ia
    if (ENV$NItest) npar<-(nobj-1)*2 + ENV$undec + npars.ia

    lambda<-rep(0,npar)
    ENV$iter<-0


    ## MAIN FITTING ROUTINE
    result<-nlm(loglik,lambda,X,nobj,partsList,ENV,hessian=TRUE,
        iterlim=1000)

    options(opt)

    ENV$nobj<-nobj
    ENV$ilabels<-ilabels

    envList<-mget(ls(ENV),envir=ENV)
    outputobj<-list(coefficients=result$estimate,
                    ll=ENV$ll,
                    fl=ENV$fl,
                    call=call,
                    result=result,
                    envList=envList,
                    partsList=partsList)
    class(outputobj) <- c("pattMod")                         #class: pattern model
    outputobj
}