How to generate a matrix of combinations

r cross-join
ProbablePattern picture ProbablePattern · Oct 22, 2010 · Viewed 18.2k times · Source

I have 5 items each of which can take on the value of 1 or -1. I want to generate a matrix that consists of rows of the possible combinations. The order of the items does not matter and the order of the combinations does not matter. I know I could do this mechanically, but I thought that someone must know a shortcut to generating this matrix. I apologize if this is similar to other questions but none of the solutions I have found can be applied to this particular problem with my programming skills.

Answer

Greg picture Greg · Oct 22, 2010 
expand.grid(c(-1,1), c(-1,1), c(-1,1), c(-1,1), c(-1,1))

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