combs {caTools} | R Documentation |

## All Combinations of k Elements from Vector v

### Description

Finds all unordered combinations of `k`

elements from vector
`v`

.

### Usage

`combs(v,k)`

### Arguments

`v` |
Any numeric vector |

`k` |
Number of elements to choose from vector |

### Value

`combs(v,k)`

(where `v`

has length `n`

) creates a matrix with
`\frac{n!}{(n-k)! k!}`

(`n`

choose `k`

) rows
and `k`

columns containing all possible combinations of `n`

elements
taken `k`

at a time.

### Author(s)

Jarek Tuszynski (SAIC) jaroslaw.w.tuszynski@saic.com

### See Also

I discovered recently that R packages already have two functions with
similar capabilities:
`combinations`

from gTools package and
Also similar to Matlab's `nchoosek`

function (http://www.mathworks.com/access/helpdesk/help/techdoc/ref/nchoosek.html)

### Examples

```
combs(2:5, 3) # display examples
combs(c("cats", "dogs", "mice"), 2)
a = combs(1:4, 2)
b = matrix( c(1,1,1,2,2,3,2,3,4,3,4,4), 6, 2)
stopifnot(a==b)
```

[Package

*caTools*version 1.18.2 Index]