For loop without repetition

Hello,

I need to create a loop that loops through 3 gas components but they cannot be put together. Basically i need to be able to use a nested for loop to get 1 and 3, 1 and 2, 2 and 3 but cannot have 1 and 1, 2 and 2 or 3 and 3... any help would be appreciated

Answer 1

[Rik]

Use perms to generate the list of all combinations and loop through the rows. Use nchoosek if you need unique combinations.