combn
Generate combinations of m elements out of x

### Description

Generate all combinations of m elements out of x or 1:n, and optionally apply a function to each. Return a list, or simplify to a matrix or an array.

### Usage

    combn(x, m, FUN = NULL, simplify = TRUE, ...)

### Arguments

x | normally an integer n, in which case combinations of elements from 1:n are returned. Otherwise x is a vector, and elements of the vector are returned.
m | the number of elements in each combination.
FUN | the function to apply to each combination. If NULL, the combinations themselves are returned, one in each column of the result.
simplify | A logical value. if FALSE, the results are returned as a list, one combination or function value in each element. If TRUE (the default), if possible, the results are simplified to a matrix or an array.
... | any optional argument to pass to FUN.

Value
normally returns a matrix with m rows and choose(n,m) columns.

- If simplify = FALSE, returns a list with choose(n,m) elements i.
- If FUN is supplied, the results of calling the function replace the combinations.

See Also
choose.
Examples

    combn(5, 3)
    combn(letters[1:5], 3)
    combn(5, 3, simplify = FALSE)
    combn(5, 3, FUN = max)
    combn(5, 3, FUN = range)
    combn(5,3, FUN = diag) # produces an array
    combn(5,3, FUN = diag, simplify = FALSE, nrow = 2)    # list of  2x2 matrices with some warnings

Package utils version 6.1.5-18
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