nchoose2

all combinations of two elements
2.7K Downloads
Updated 28 Feb 2019

View License

NCHOOSE2 - all combinations of two elements

Y = NCHOOSE2(X) returns all combinations of two elements of the array X. It is the fast, vectorized version of NCHOOSEK(X,2). X can be any type of array. When X is a scalar integer > 1, it returns X*(X-1)/2.

Example:
nchoose2([10 20 30 40])
% -> 10 20
% 10 30
% 10 40
% 20 30
% 20 40
% 30 40

nchoose2({'a','b','c','d','e'})
% -> 'a' 'b'
% 'a' 'c'
% ...
% 'c' 'e'
% 'd' 'e'

See also nchoosek, perms
combn, nchoose, allcomb (on the File Exchange)

Cite As

Jos (10584) (2024). nchoose2 (https://www.mathworks.com/matlabcentral/fileexchange/20144-nchoose2), MATLAB Central File Exchange. Retrieved .

MATLAB Release Compatibility
Created with R2018b
Compatible with any release
Platform Compatibility
Windows macOS Linux
Categories
Find more on Argument Definitions in Help Center and MATLAB Answers
Acknowledgements

Inspired by: nCtwo

Inspired: nchoose3, VChooseK

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!
Version Published Release Notes
3.2.0.1

added image

3.2.0.0

edited internal comments

3.1.0.0

fixed bug for scalar input

3.0.0.0

When X is a scalar integer > 1, it returns X*(X-1)/2.

2.2.0.0

checked for R2017b, fixed comma's

1.0.0.0

fixed error with input having less than 2 elements