R/gdm_calc_prob.R

In CDM: Cognitive Diagnosis Modeling

## File Name: gdm_calc_prob.R
## File Version: 0.04

#######################################
# calculate probability in the GDM
gdm_calc_prob <- function( a, b, thetaDes, Qmatrix, I, K, TP, TD)
{
    probs <- array( 0, dim=c(I,K+1,TP) )    # categories 0, ..., K
    for (kk in 1:K){
        l0 <- matrix( b[,kk], nrow=I,ncol=TP)
        for (td in 1:TD){     # kk <- 1    # category 1
            # td <- 1
            l0 <- l0 + a[, td, kk ] * Qmatrix[, td, kk] * matrix( thetaDes[, td ], nrow=I,ncol=TP, byrow=T)
        }
        probs[,kk+1,] <- l0
    }
    probs <- exp( probs )
    probs1 <- probs[,1,]
    for (kk in 2:(K+1)){
        probs1 <- probs1 + probs[,kk,]
    }
    for (kk in 1:(K+1)){
        probs[,kk,] <- probs[,kk,] / probs1
    }
    return(probs)
}

.gdm.calc.prob <- gdm_calc_prob