R: All k possible combinations from n elements

All k possible combinations from n elements {Rfast} | R Documentation

## All k possible combinations from n elements

### Description

All k possible combinations from n elements.

### Usage

    comb_n(n, k,simplify=TRUE)

### Arguments

`n` | A positive INTEGER number or a vector with numbers.
`k` | A positive integer number at most equal to n or at most equal to the length of n, if n is a vector.
`simplify` | A logical value for return List instead of matrix.

### Value

A matrix with k columns and rows equal to the number of possible unique combinations of n with k elements. If simplify is set to TRUE then a list with k values where each value has length equal to the number of possible unique combinations of n with k elements.

### Author(s)

Manos Papadakis and Marios Dimitriadis

R implementation and documentation: Manos Papadakis <papadakm95@gmail.com> and Marios Dimitriadis <kmdimitriadis@gmail.com>.

### References

Nijenhuis A. and Wilf H.S. (1978). Combinatorial Algorithms for Computers and Calculators. Academic Press, NY.

### See Also

`nth, colMaxs, colMins, colrange`

### Examples

    system.time( comb_n(20, 4) )
    system.time( combn(20, 4) )
    x <- rnorm(5)
    res<-comb_n(x, 3)

[Package Rfast version 2.0.4 Index]