Extracts Unique Item Response Patterns

Extracts unique item response patterns.

Usage

immer_unique_patterns(dat, w=rep(1, nrow(dat)))

Arguments

dat

Data frame containing integer item responses

w

Optional vector of weights

Value

A list with entries

y

Data frame with unique item response patterns

w

Vector of frequency weights

y_string

Item response pattern coded as a string

See also

See mirt::expand.table for back-converting unique item response patterns into a data frame with item responses.

Examples

#############################################################################
# EXAMPLE 1: Unique item response patterns data.read
#############################################################################

data( data.read, package="sirt")
dat <- data.read

# extract item response patterns
res <- immer::immer_unique_patterns(dat)

if (FALSE) {
# back-conversion with expand.table
dat2 <- mirt::expand.table( cbind( res$y, res$w ) )
# check correctness
colMeans(dat)
colMeans(dat2)
}