R/skillspace.approximation.R

In CDM: Cognitive Diagnosis Modeling

## File Name: skillspace.approximation.R
## File Version: 0.11


#-- skill space approximation
skillspace.approximation <- function( L, K, nmax=5000 )
{
    CDM_require_namespace("sfsmisc")
    n <- nmax
    ndim <- K
    res <- sfsmisc::QUnif(n, p=ndim, leap=409)
    res <- 1*(res>.5)
    res <- rbind( rep( 0,ndim), rep(1,ndim), res )
    v1 <- paste0("P", res[,1] )
    for (vv in 2:ndim){
        v1 <- paste0( v1, res[,vv] )
    }
    rownames(res) <- v1
    res <- res[ ! duplicated(v1), ]
    res <- res[ 1:L, ]
    res <- res[ order( rownames(res) ), ]
    return(res)
}