fastcombn | R Documentation |

Generate all combinations of the elements of x taken m at a time. If x is a positive integer, returns all combinations of the elements of seq(x) taken m at a time.

```
fastcombn(x, m, FUN = NULL, simplify = TRUE, ...)
combn_prim(x, m, simplify = TRUE)
```

`x` |
vector source for combinations, or integer n for x <- seq(n). |

`m` |
number of elements to choose. |

`FUN` |
function to be applied to each combination; default ‘NULL’ means the identity, i.e., to return the combination (vector of length ‘m’). |

`simplify` |
logical indicating if the result should be simplified to a matrix; if FALSE, the function returns a list. |

`...` |
Further arguments passed on to |

Factors

`x`

are accepted.-
`combn_prim`

is a simplified (but faster) version of the`combn`

function. Does nok take the`FUN`

argument. -
`fastcombn`

is intended to be a faster version of the`combn`

function.

A matrix or a list.

Søren Højsgaard

`combn`

```
x <- letters[1:5]; m <- 3
fastcombn(x, m)
combn(x, m)
combn_prim(x, m)
x <- letters[1:4]; m <- 3
fastcombn(x, m, simplify=FALSE)
combn(x, m, simplify=FALSE)
combn_prim(x, m, simplify=FALSE)
x <- 1:10; m <- 3
fastcombn(x, m, min)
combn(x, m, min)
x <- factor(letters[1:8]); m <- 5
if (require(microbenchmark)){
microbenchmark(
combn(x, m, simplify=FALSE),
combn_prim(x, m, simplify=FALSE),
fastcombn(x, m, simplify=FALSE),
times=50
)
}
```

gRbase documentation built on Sept. 22, 2023, 5:12 p.m.

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