R/lavaanify.grep.MEASERR.R

In TAM: Test Analysis Modules

## File Name: lavaanify.grep.MEASERR.R
## File Version: 9.09

#####################################################
# grep term "MEASERR" for measurement errors
lavaanify.grep.MEASERR <- function( lavmodel )
{
    lavmodel0 <- lavmodel
    lavmodel <- gsub( ";", "\n", lavmodel, fixed=TRUE)
    lavmodel <- gsub( " ", "", lavmodel )
    syn <- strsplit( lavmodel, split="\n", fixed=TRUE )[[1]]
    syn <- syn[ syn !="" ]
    SS <- length(syn)
    dfr <- data.frame( "index"=1:SS, "syn"=syn )
    dfr$MEASERR <- 1 * ( substring( dfr$syn, 1, 7 )=="MEASERR" )
    dfr$MEASERR1 <- 1 * ( substring( dfr$syn, 1, 8 )=="MEASERR1" )
    dfr$MEASERR0 <- 1 * ( substring( dfr$syn, 1, 8 )=="MEASERR0" )
    dfr$true <- NA
    dfr$obs <- NA
    dfr$errvar <- NA

    ind <- which( dfr$MEASERR==1 )
    if ( length(ind) > 0 ){
    # decompose term MEASERR
        for (ii in ind ){
            l1 <- paste(dfr$syn[ii] )
            l1 <- gsub( "MEASERR1(", "", l1, fixed=TRUE )
            l1 <- gsub( "MEASERR0(", "", l1, fixed=TRUE )
            l1 <- gsub( ")", "", l1, fixed=TRUE )
            l2 <- strsplit( l1, "," )[[1]]
            dfr[ ii, "true" ] <- l2[1]
            dfr[ ii, "obs" ] <- l2[2]
            dfr[ ii, "errvar" ] <- as.numeric( l2[3] )
        }
        # create new string of lavaan syntax
        N1 <- nrow(dfr)
        lavmodel0 <- ""
        for (nn in 1:N1){
            if ( dfr$MEASERR[nn]==0 ){
                lavmodel0 <- paste0( lavmodel0, "\n", dfr[nn,"syn"] )
            }
            if ( dfr$MEASERR[nn]==1 ){
                lavmodel0 <- paste0( lavmodel0, "\n",
                            dfr[nn,"true"], "=~1*", dfr[nn,"obs"] )
                lavmodel0 <- paste0( lavmodel0, "\n",
                            dfr[nn,"obs"], "~~", dfr[nn,"errvar"], "*", dfr[nn,"obs"] )
            }
            if ( dfr$MEASERR0[nn]==1 ){
                lavmodel0 <- paste0( lavmodel0, "\n",
                            dfr[nn,"true"], "~~", dfr[nn,"true"]  )
            }
        }
    }
    return(lavmodel0)
}
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