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quantreg (version 5.98)

combos: Ordered Combinations

Description

All m combinations of the first n integers taken p at a time are computed and return as an p by m matrix. The columns of the matrix are ordered so that adjacent columns differ by only one element. This is just a reordered version of combn in base R, but the ordering is useful for some applications.

Usage

combos(n,p)

Value

a matrix of dimension p by choose(n,p)

Arguments

n

The n in n choose p

p

The p in n choose p

References

Limin Xiang and Kazuo Ushijima (2001) "On O(1) Time Algorithms for Combinatorial Generation," Computer Journal, 44(4), 292-302.

Examples

Run this code
H <- combos(20,3)

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