R/tam_mml_3pl_calc_prob.R

In TAM: Test Analysis Modules

## File Name: tam_mml_3pl_calc_prob.R
## File Version: 1.32

#--- Calculation of probabilities
tam_mml_3pl_calc_prob <- function(iIndex, A, AXsi, B, xsi, theta,
            nnodes, maxK, recalc=TRUE, guess, subtract_max=TRUE )
{
    if(recalc){
        LI <- length(iIndex)
        LXsi <- dim(A)[3]
        AXsi.tmp <- array( 0, dim=c( LI, maxK, nnodes ) )
        for (kk in 1:maxK){
            A_kk <- matrix( A[ iIndex, kk, ], nrow=LI, ncol=LXsi )
            AXsi.tmp[, kk, 1:nnodes ] <- A_kk %*% xsi
        }
        AXsi[iIndex,]=AXsi.tmp[,,1]
    } else {
        AXsi.tmp <- array( AXsi, dim=c( length(iIndex), maxK, nnodes ) )
    }

    Btheta <- array(0, dim=c(length(iIndex), maxK, nnodes) )
    for( dd in 1:ncol(theta) ){
        Btheta <- Btheta + array(B[iIndex,,dd,drop=FALSE] %o% theta[,dd], dim=dim(Btheta))
    }

    # rprobs <- ( rr <- exp(Btheta+AXsi.tmp) )/aperm( array( rep( colSums( aperm( rr, c(2,1,3) ),
    #                dims=1, na.rm=TRUE),    maxK ), dim=dim(rr)[c(1,3,2)] ), c(1,3,2) )

    #*** subtract maximum and use in Rcpp
    rr0 <- Btheta + AXsi.tmp
    if ( subtract_max){
        rr1 <- tam_calc_prob_helper_subtract_max( rr0=rr0 )
    } else {
        rr1 <- rr0
    }

    rr <- exp(rr1)
    rprobs <- rr / aperm( array( rep( colSums( aperm( rr, c(2,1,3) ),
                    dims=1, na.rm=TRUE),  maxK ), dim=dim(rr)[c(1,3,2)] ), c(1,3,2) )

    # include guessing
    rprobs0 <- rprobs

    ind <- which(guess[ iIndex ] > 1E-6 )
    if ( length(ind) > 0 ){
        rprobs[ ind, 2, ] <- guess[ind] + ( 1-guess[ind] ) * rprobs0[ind,2,]
        rprobs[ ind, 1, ] <- 1 - rprobs[ ind, 2, ]
    }

    return(list("rprobs"=rprobs, "AXsi"=AXsi, "rprobs0"=rprobs0 ))
}

.mml.3pl.calc_prob.v5 <- tam_mml_3pl_calc_prob