# fwd.combn: Generate all combinations of elements of x taken m at a time In forward: Robust Analysis using Forward Search

 fwd.combn R Documentation

## Generate all combinations of elements of x taken m at a time

### Description

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. If argument `fun` is not null, applies a function given by the argument to each point. If simplify is `FALSE`, returns a list; else returns a vector or an array. Optional arguments `...` are passed unchanged to the function given by argument `fun`, if any.

### Usage

```fwd.combn(x, m, fun = NULL, simplify = TRUE, ...)
fwd.nCm(n, m, tol = 1e-08)
```

### Arguments

 `x` a vector or a single value. `n` a positive integer. `m` a positive integer. `fun` a function to be applied to each combination. `simplify` logical, if `TRUE` returns a vector or an array, otherwise a list. `tol` optional, tolerance value. `...` optional arguments passed to `fun`.

### Value

Returns a vector or an array if `simplify = TRUE`, otherwise a list.

### Note

Renamed by Kjell Konis for inclusion in the Forward Library 11/2002

Scott Chasalow

### References

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

### Examples

```fwd.combn(letters[1:4], 2)
fwd.combn(10, 5, min)      # minimum value in each combination
# Different way of encoding points:
fwd.combn(c(1,1,1,1,2,2,2,3,3,4), 3, tabulate, nbins = 4)
# Compute support points and (scaled) probabilities for a
# Multivariate-Hypergeometric(n = 3, N = c(4,3,2,1)) p.f.:
table(t(fwd.combn(c(1,1,1,1,2,2,2,3,3,4), 3, tabulate, nbins=4)))
```

forward documentation built on May 9, 2022, 9:05 a.m.