combinatoricsCount: Number of combinations/permutations In RcppAlgos: High Performance Tools for Combinatorics and Computational Mathematics

 comboCount R Documentation

Number of combinations/permutations

Description

Calculate the number of combinations/permutations of a vector chosen `m` at a time with or without replacement. Additionally, these functions can calculate the number of combinations/permutations of multisets.

Usage

``````comboCount(v, m = NULL, repetition = FALSE, freqs = NULL)

permuteCount(v, m = NULL, repetition = FALSE, freqs = NULL)
``````

Arguments

 `v` Source vector. If `v` is a positive integer, it will be converted to the sequence `1:v`. If `v` is a negative integer, it will be converted to the sequence `v:-1`. All atomic types are supported (See `is.atomic`). `m` Number of elements to choose. If `repetition = TRUE` or `freqs` is utilized, `m` can exceed the length of `v`. If `m = NULL`, the length will default to `length(v)` or `sum(freqs)`. `repetition` Logical value indicating whether combinations/permutations should be with or without repetition. The default is `FALSE`. `freqs` A vector of frequencies used for producing all combinations/permutations of a multiset of `v`. Each element of `freqs` represents how many times each element of the source vector, `v`, is repeated. It is analogous to the `times` argument in `rep`. The default value is `NULL`.

Value

A numerical value representing the total number of combinations/permutations.

Note

When the number of results exceeds `2^{53} - 1`, a number of class `bigz` is returned.

`comboGeneral`, `permuteGeneral`

Examples

``````## Same interface as the respective "general" functions:
## i.e. comboGeneral & permuteGeneral

permuteCount(-5)
permuteCount(5)
comboCount(25, 12)
permuteCount(15, 7, TRUE)
comboCount(25, 12, freqs = rep(2, 25))

## Return object of class 'bigz'
comboCount(250, 15, freqs = rep(2, 250))
``````

RcppAlgos documentation built on Oct. 3, 2023, 1:07 a.m.