permutation: Find All Permutations of Consecutive Integers

In swnydick/mupp: Multi-Unidimensional Pairwise Preference (MUPP) IRT Model

Find All Permutations of Consecutive Integers

Description

Given an consecutive integer vector of length n, find all permutations of that vector.

Usage

find_all_permutations(n, init = 0L)

find_permutation_order(n, index = 1L, init = 0L)

find_permutation_index(order)

Arguments

n	an integer greater than 0
init	an integer indicating the initial starting value for the set of integers included in the permutation. See Details.
index	an integer between 1 and n indicatng which permutation to select (using R indexing rather than C indexing)
order	an integer vector indicating the response/permutation order that should be checked against

Details

init is useful for indexing C vs R code. If init = 0, then the indices will work with 0 indexed languages, such as C or Python. If init = 1, then the indices will work with 1 indexed languages, such as R.

Value

For find_all_permutations, a A matrix of size n! x n, where each row is a unique permutation. For find_permutation_order, the index row into the permutation matrix (where "index" uses R indexing). For find_permutation_index the index of the permutation matrix that leads to a particular order.

Note

find_permutation_order and find_permutation_index both use R indexing for determining the row in the permutation matrix and are almost inverses of each other. The reason they are "almost" inverses and not true inverses is because find_permutation_index needs only an integer vector and will standardize that vector to be between 1 and n. Therefore, the order is unique only up to a monotonic transformation.

Author(s)

Steven Nydick, [e-mail]

swnydick/mupp documentation built on July 8, 2022, 7:59 a.m.