R/immer_unique_patterns.R

In immer: Item Response Models for Multiple Ratings

## File Name: immer_unique_patterns.R
## File Version: 0.094


#--- extract unique item response patterns from dataset
immer_unique_patterns <- function( dat, w=rep(1,nrow(dat) ) )
{
    I <- ncol(dat)
    N <- nrow(dat)
    v1 <- 'P'
    v2 <- NULL
    for (ii in 1L:I){
        # ii <- 1
        dig2 <- log( max( dat, na.rm=TRUE ) + 2, 10 ) >=1
        na_code <- if ( dig2 ){  99 } else { 9 }
        y <- dat[,ii]
        y[is.na(y)  ] <- na_code
        v1 <- paste0( v1, y )
    }

    f1 <- rowsum( matrix(w,ncol=1), v1 )
    NP <- nrow(f1)
    y <- matrix( 0, nrow=NP, ncol=I)
    colnames(y) <- colnames(dat)
    #*** compute dataframe of indices
    dfr <- data.frame(item=1L:I )
    h1 <- if( dig2 ){  seq(1,2*I,2) } else { 1L:I }
    dfr$start <- h1 + 1
    dfr$end <- dfr$start + dig2
    #*** extract data
    for (ii in 1L:I){
        y0 <- substring( paste( rownames(f1) ), dfr[ii,'start'],
                    dfr[ii,'end'] )
        h1 <- as.numeric( y0 )
        h1[ h1==na_code ] <- NA
        y[,ii ] <- h1
    }
    #*** output
    res <- list( y=y, w=f1[,1], y_string=paste( rownames(f1) ) )
    return(res)
}