R/slca_inits_skill_distribution.R

In CDM: Cognitive Diagnosis Modeling

## File Name: slca_inits_skill_distribution.R
## File Version: 0.06

slca_inits_skill_distribution <- function( delta.designmatrix, delta.init,
        delta.linkfct, G, K, I )
{
    TP <- nrow(delta.designmatrix)

    if (  ! is.null(delta.init) ){
        delta <- delta.init
        if ( delta.linkfct=="log"){
            pik <- exp( delta.designmatrix %*% delta.init[,1] )
        } else {
            pik <- stats::plogis( delta.designmatrix %*% delta.init[,1] )
        }
    } else {
        pik <- cdm_sumnorm( rep( 1 /TP, TP ) + stats::runif(TP, 0, .5 ) )
        if ( delta.linkfct=="logit"){
            g1 <- solve( crossprod( delta.designmatrix )) %*% t( delta.designmatrix) %*% pik
            delta <- matrix( g1[,1], nrow=ncol(delta.designmatrix), ncol=G)
        } else {
            delta <- matrix( 0, ncol(delta.designmatrix), G )
            delta[1,] <- 1
        }
    }

    pi.k <- matrix( 0, TP, G )
    for (gg in 1:G){
        pi.k[,gg] <- pik
    }
    n.ik <- array( 0, dim=c(TP,I,K+1,G) )
    #--------- output
    res <- list(TP=TP, n.ik=n.ik, pi.k=pi.k, delta=delta)
    return(res)
}