mirt: thetaComb – R documentation

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thetaComb

Create all possible combinations of vector input

Description

This function constructs all possible k-way combinations of an input vector. It is primarily useful when used in conjunction with the mdirt function, though users may have other uses for it as well. See expand.grid for more flexible combination formats.

Usage

thetaComb(theta, nfact, intercept = FALSE)

Arguments

`theta`	the vector from which all possible combinations should be obtained
`nfact`	the number of observations (and therefore the number of columns to return in the matrix of combinations)
`intercept`	logical; should a vector of 1's be appended to the first column of the result to include an intercept design component? Default is `FALSE`

Value

a matrix with all possible combinations

Author(s)

Phil Chalmers rphilip.chalmers@gmail.com

References

Chalmers, R., P. (2012). mirt: A Multidimensional Item Response Theory Package for the R Environment. Journal of Statistical Software, 48(6), 1-29. doi: 10.18637/jss.v048.i06

Examples

# all possible joint combinations for the vector -4 to 4
thetaComb(-4:4, 2)

# all possible binary combinations for four observations
thetaComb(c(0,1), 4)

# all possible binary combinations for four observations (with intercept)
thetaComb(c(0,1), 4, intercept=TRUE)

mirt

Multidimensional Item Response Theory

v1.33.2

GPL (>= 3)

Authors

Phil Chalmers [aut, cre] (<https://orcid.org/0000-0001-5332-2810>), Joshua Pritikin [ctb], Alexander Robitzsch [ctb], Mateusz Zoltak [ctb], KwonHyun Kim [ctb], Carl F. Falk [ctb], Adam Meade [ctb], Lennart Schneider [ctb], David King [ctb], Chen-Wei Liu [ctb], Ogreden Oguzhan [ctb]

Initial release