[Jprogramming] Getting all pairs of integers up to some value

[Joe Bogner]

For very low range numbers (less than 10), this could work

The problem with this approach is that it generates all permutations !n

(~.@(] /:"1 ])@(2]\])@;@(i.@!@# A. ]) i.) 4



On Fri, Dec 18, 2015 at 7:58 AM, 'Jon Hough' via Programming
<programming at jsoftware.com> wrote:
> I've spent an hour on this, and am frustrated that I couldn't figure out a way to do it (without using for_j or while).
>
> I want to get all pairs ( pair order not important e.g. 2 3 is the same as 3 2) of integers up to some value.
>
> e.g. up to 4:
>
> 0 1
> 0 2
> 0 3
> 1 2
> 1 3
> 2 3
>
> in frustration this is what I came up with (for the case of 10):
> /:~ ~. /:~"1  (1000 # 2) ? 10
>
> which works but is not a very good solution.
>
> Any nice solutions?
>
> Thanks,
>
> Jon
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