R/gdina_proc_split_item_response_patterns.R

In CDM: Cognitive Diagnosis Modeling

## File Name: gdina_proc_split_item_response_patterns.R
## File Version: 0.07

gdina_proc_split_item_response_patterns <- function( item.patt, J, freq_weights=TRUE,
        resp=NULL, dat.items=NULL  )
{
    #---------- use frequency weights
    if (freq_weights ){
        # split item response pattern in a data frame with items as columns
        spl <- sapply( as.vector(item.patt[,1]), FUN=function(ii){ strsplit( ii, split=NULL) } )
        item.patt.split <- matrix( rep( 0, length(spl) * J ), ncol=J )
        for (ll in 1:length(spl) ){
            item.patt.split[ ll, ] <- as.numeric( spl[[ll]] )
        }
        # response pattern matrix: each observed entry corresponds to a 1,
        # each unobserved entry to a 0
        resp.patt <- 1* ( item.patt.split !=9 )
    }
    #---------- do not use frequency weights
    if ( ! freq_weights ){
        item.patt.split <- dat.items
        resp.patt <- resp
    }
    # number of item response patterns
    IP <- nrow(item.patt.split)
    #---- OUTPUT
    res <- list(IP=IP, resp.patt=resp.patt, item.patt.split=item.patt.split)
    return(res)
}