R/genPattern.R

In catR: Generation of IRT Response Patterns under Computerized Adaptive Testing

genPattern<-function (th, it, model = NULL, D = 1, seed = NULL) 
{
    it <- rbind(it)
    if (!is.null(seed)) 
        set.seed(seed)
    res <- matrix(NA, length(th), nrow(it))
    for (iter in 1:length(th)) {
        if (is.null(model)) 
            res[iter, ] <- rbinom(nrow(it), 1, Pi(th[iter], it, 
                model = model, D = D)$Pi)
        else {
            pr <- Pi(th[iter], it, model = model, D = D)$Pi
            RES <- NULL
            for (i in 1:nrow(pr)) {
                pp <- pr[i, ][!is.na(pr[i, ])]
                vec <- rmultinom(n = 1, size = 1, prob = pp)
                RES[i] <- (1:nrow(vec))[vec[, 1] == 1] - 1
            }
            res[iter, ] <- RES
        }
    }
    if (length(th) == 1) 
        res <- as.numeric(res)
set.seed(NULL)
    return(res)
}