## File Name: xxirt_compute_itemprobs.R
## File Version: 0.214
# compute item probabilities
xxirt_compute_itemprobs <- function( item_list, items, Theta, ncat,
partable, partable_index, item_index=NULL )
{
TP <- nrow(Theta)
maxK <- max(ncat)
if ( is.null(item_index) ){
I <- length(items)
item_index <- 1:I
}
I <- length(item_index)
# compute item probabilities as a function of theta
probs <- array( 0, dim=c(I,maxK,TP) )
for (jj in 1:I){
ii <- item_index[jj]
item_ii <- item_list[[ii]]
par_ii <- partable[ partable_index[[ii]], 'value' ]
ncat_ii <- ncat[ii]
arg_ii <- list( par=par_ii, Theta=Theta, ncat=ncat_ii )
probs_ii <- do.call( item_ii$P, arg_ii )
probs[ jj, 1:ncat_ii,] <- t(probs_ii)
}
return(probs)
}
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