Occasionally known as “featuritis”.

hi, so I wrote a function but I'm not happy with it... can somebody suggest improvemens? For one it's way too long and for two, I can't help but think there might have been some built in or pattern I'm not familiar with

the function is: idxs ←{,[0 1]↑(1 0 1 0 1 0⊂⊢)¨{⍵,(0 3⊃¨⊂⍵)}¨((0⌷⊢∘⍉)∘.,(0⌷⊢))⍳⍴⍵}

and you use it like this (idxs data) ⊃¨⊂ data

what it does is it takes a table and "unpivots" it

you can only make a whole message a code block (you can edit the message and ctrl+k)

┌──┬───┬───┐
│  │c1 │c2 │
├──┼───┼───┤
│r1│v11│v12│
├──┼───┼───┤
│r2│v21│v22│
├──┼───┼───┤
│r3│v31│v32│
└──┴───┴───┘
↓
┌──┬──┬───┐
│  │  │   │
├──┼──┼───┤
│  │c1│c1 │
├──┼──┼───┤
│  │c2│c2 │
├──┼──┼───┤
│r1│  │r1 │
├──┼──┼───┤
│r1│c1│v11│
├──┼──┼───┤
│r1│c2│v12│
├──┼──┼───┤
│r2│  │r2 │
├──┼──┼───┤
│r2│c1│v21│
├──┼──┼───┤
│r2│c2│v22│
├──┼──┼───┤
│r3│  │r3 │
├──┼──┼───┤
│r3│c1│v31│
├──┼──┼───┤
│r3│c2│v32│
└──┴──┴───┘

I think {↑{a b←⍵ ⋄ (a 0)(0 b)(a b)}¨,⍳⍴⍵} works

faster fancy alternative - {↓1 0 2⍉↑(1 0)(0 1)1×⍤1¨⊂↑,⍳⍴⍵}

Nice trick with (1 0)(0 1)1×⍤1 ...

thanks I learned something

@elliptic00 The Julia language is perhaps the closest.

@Chewxy For next time, consider posting on:

{(,⍳⍴⍵)∘.×(1 0)(0 1)(1 1)} seems to work too

{(,⍳⍴⍵)∘.×(1 0)(0 1)1}

It seems to be slightly slower than dzaima's fast solution, but I have no idea why

@rabbitgrowth that'll be because some pretty funky low-level things; my guess would be that × on nested arrays goes some generic path that does effectively ¨, not thinking too much about the performance in the case the arrays that's done on are tiny (which they are); whereas ↑ and ↓ are specifically about manipulating array sizes, so they've got more effort put in to be fast on small arrays. (and ×⍤1 is gonna be very fast because its done on large flat arrays)

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@Adám 391680

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@Adám Jelly too

Sure, but Jelly isn't really on-topic here.

@Adám I only see Python? Or should I create an account?

Yes, there appears to be a bug where you only see Python until you have an account.

ok done. Just 14 votes now? We must be able to do it better. And almost half of these languages I do not take serious (including Basic and Pascal)