The Nineteenth Byte

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00:01

0

Background -rot transform (read as "minus-rot transform") is a sequence transformation I just invented. This transform is done by viewing the sequence as a stack in Forth or Factor (first term on the top) and repeatedly applying -rot +. -rot is a command that moves the top of the stack to two pla...

Dude coinheringaahing

@NewPosts @Bubbler How short is your crazy APL/J/Jelly solution?

Just so I have a point of reference to get double :P

Bubbler

@Dudecoinheringaahing My first working solution was 36 bytes in J

Dude coinheringaahing

Ok, so there's not some crazy array-lang trick involved? :P

Bubbler

Not an arraylang trick per se, though I used a J-specific builtin

I think Jelly has the same thing

exedraj

Can we take the input in reverse? — Dude coinheringaahing 9 mins ago

Bubbler

00:14

@Dudecoinheringaahing No. — Bubbler 1 min ago

exedraj

ah well. "yes" would have shaved a byte off my answer lol

Dude coinheringaahing

@Bubbler Your challenges have a tendency to make me say "blegh" about my Jelly answers to them :P

Bubbler

:P

Dude coinheringaahing

I'm sure there's a more elegant way, and I was so happy about the ḣ2S;ɗḢo, before it got ruined :/

Bubbler

btw, the J builtin I abused is this

exedraj

00:17

@Dudecoinheringaahing Imagine using letters

Dude coinheringaahing

@Bubbler œ? in Jelly, I believe

Bubbler

Where should I post if I find a minor typo in a SO blog post?

Dude coinheringaahing

Ping Catija if it's a minor one (here or the Tavern should be fine), open a bug report on MSE if its more than a couple of mistyped words

rak1507

there's an interesting pattern there but I can't see any nice way of getting it with some sort of scan

[a, b + c]
[a, b + c, a + d]
[a, b + c, a + d, b + c + e]
[a, b + c, a + d, b + c + e, a + d + f]
[a, b + c, a + d, b + c + e, a + d + f, b + c + e + g]
[a, b + c, a + d, b + c + e, a + d + f, b + c + e + g, a + d + f + h]

Bubbler

Gotta visit the tavern I guess

Dude coinheringaahing

00:27

chat.meta.stackexchange.com/rooms/89/tavern-on-the-meta

rak1507

does jelly have 'uninterleave'?

vyxal does, but there's already a very short vyxal solution

Dude coinheringaahing

Œœ

exedraj

@rak1507 but you can't really compare it to Jelly, because it uses the fact that it's already operating on a stack

rak1507

yes

tio.run/##y0rNyan8///opKOT//@PNtQx0jHWMdExjQUA sorry, should this not do something?

Dude coinheringaahing

Use arguments not input

rak1507

00:32

oh, it should be an arg

yes

out of practice

exedraj

@Dudecoinheringaahing is using a for-loop len(input) - 1 times any shorter somehow?

Dude coinheringaahing

Not really

Jelly's always-on implicit print hurts it here

rak1507

shortest way to do [1, 2, 3, 4, 5] -> [1, 3, 4, 5]?

searched for 'pop' (didn't find anything)

Dude coinheringaahing

Jelly, 4 bytes Ḣ;ḊƊ

rak1507

really

Dude coinheringaahing

00:36

The Ɗ is to keep it as a single link, isn't always required

rak1507

ok, whatever

Dude coinheringaahing

@rak1507 How would Vyxal do it?

rak1507

no idea, I don't know vyxal

Dude coinheringaahing

Don't you? Huh, I've lost track of who does and doesn't :P

Bubbler

You're probably looking for "swap the first two" instead?

rak1507

00:37

yeah that'd be better

thanks :P

no idea how to do that either, @Dudecoinheringaahing ?

exedraj

@rak1507 is that "remove second item"?

rak1507

indeed it is

Dude coinheringaahing

@rak1507 ḣ2Uo, assuming no elements are 0

rak1507

can that be assumed? @Bubbler

Bubbler

Nope

rak1507

00:39

darn

Dude coinheringaahing

ḣ2Uḷ" if there can be zeros

rak1507

how on earth does Ḣ;Ḋ work btw

Dude coinheringaahing

@Bubbler Ugh

rak1507

oh, modifies the list

exedraj

@Dudecoinheringaahing :ẏ1oİ

duplicate, range(0, len(top)), remove 1, vectorised index

actually, ḣḢJ works

rak1507

00:43

tio.run/##y0rNyan8///hjsVGoQ93bFc6tPXopKOTD7cc3aPvdmgrXPj////…

some potential maybe?

exedraj

@rak1507 yor Nyan...

don't encourage the cat people.

rak1507

tio.run/##ATUAyv9qZWxsef//4bijMlXhuLciCsOHxZLFk8OExbwvRsOH////…

14 bytes

Dude coinheringaahing

13 bytes

rak1507

btw, please can I post this as my own answer with credit? it's sufficiently different imo

Dude coinheringaahing

Yeah, of course :P

rak1507

00:44

thanks

ah, Z rather than z/

Bubbler

I don't think it's correct

rak1507

ḣ2Uḷ" annoys me

@Bubbler oh no

exedraj

@Bubbler you're right

Dude coinheringaahing

Doesn't work

rak1507

oh right, just have to replace the last C with an H

tio.run/##ASgA1/9qZWxsef//4bijMlXhuLciCsOHxZLFk8OEWkbhuIr///…

should work

Dude coinheringaahing

00:47

looks like it

exedraj

@rak1507 *replaces with D instead*

rak1507

ḣ2Uḷ"µŒœÄZFḊ

@exedraj yeah, forgot I wanted tail not head

actually ends up shorter because you don't have to do the rotation twice

Bubbler

Looks good

Dude coinheringaahing

Feels like there's some way of shortening ḣ2Uḷ"µ

rak1507

probably

I'll get writing the explanation

Dude coinheringaahing

00:50

11 bytes

rak1507

ooh nice

ok golf langs can be quite cool, even if you have the idea it can be hard and interesting golfing it

Dude coinheringaahing

:P

rak1507

anything unclear in the explanation?

Dude coinheringaahing

05AB1E should win this, but it's being held back by design issues ಠ_ಠ

@rak1507 I'd typically do both heads first, then the ṭ below in the explanation, but that's definitely a point of preference :P

rak1507

rip

ok, that makes sense

done

exedraj

01:04

@Dudecoinheringaahing how many bytes do you have in 05AB1E?

Bubbler

In general I think I write 1 then 2 when I have a 2-1 combo (or just combine both in one line)

emanresu A

CMC: Give your cat control of your keyboard.

exedraj

@emanresuA can't.

catn't

rak1507

I don't have a cat so that may prove slightly difficult

Dude coinheringaahing

Ideal 05AB1E would be splat; swap; wrap; uninterleave; cumsums; interleave; remove_head, where each of those is 1 byte (for a total of 7), but .¥ (cumsum) doesn't vectorise, and, because the stack is the wrong way around, it needs `rsr) instead of `s) ಠ_ಠ

exedraj

01:05

@Dudecoinheringaahing I have an 8 byter in 05AB1E

Bubbler

@emanresuA wstgyk;io

Dude coinheringaahing

Plus, .¥ prepends 0 when it does cumsum ಠ_ಠ

Bubbler

It was my imaginary cat in my head

Dude coinheringaahing

@exedraj Using your Vyxal method?

exedraj

correct

emanresu A

01:06

HaLpI 'M TrAped inSiDe ThE BoDy Of A CaT ! /??

exedraj

@Dudecoinheringaahing if length of stack was 1 byte, I could get a 7 lol

Dude coinheringaahing

Yeah, I was expecting that. What annoys me is that 05AB1E should have the perfect builtins and stack model to make this a walk in the park, but it just misses the mark

exedraj

Why did adnan make length of stack .g?

rak1507

yea, so close but so far

Dude coinheringaahing

@exedraj Because length is g

rak1507

01:08

@exedraj not as if getting the length of something is an extremely common operation or anything, nahhhh

Bubbler

Well, length of stack is rarely needed for a high-level language :P

exedraj

@rak1507 but why does it have to be a digraph

rak1507

I was being sarcastic

exedraj

yeah I could tell

Dude coinheringaahing

That's one thing I like about Jelly vs stack languages is that you never have to balance builtins that operate on either the stack or the top element

rak1507

01:09

@exedraj oh, well, yeah I agree it shouldn't be a digraph that's dumb

11 in jelly is pretty decent really, would be nice if swap first two elements was a single byte, not sure how often it comes up but at least a digraph maybe

Dude coinheringaahing

The thing is that g is well-defined for integers (cast to string, length), so it can't do what O does (sum of ToS if list, else sum of stack)

exedraj

inb4 stax wins with source compression somehow

rak1507

lol

Dude coinheringaahing

@rak1507 Head rot (rotate the first n elements one step to the left) would be great tbh

rak1507

yeah

would save on the separator as well right

Dude coinheringaahing

01:11

So that would be œṙ2, and you could get rid of the separator

9 bytes in Jelly for a stack-centered challenge is pretty good :P

rak1507

and if it was a single byte it could be 8

Bubbler

Next up: deque-centered challenge :P

Dude coinheringaahing

@rak1507 Yeah, if Œs (or whatever) was special cased as œṙ2 it'd match Vyxal, which has the right stack model and the builtin as a builtin

rak1507

yeah

exedraj

> the builtin as a builtin

that lowkey confused me at first

Dude coinheringaahing

01:15

Every 60 seconds, a minute passes in Africa :P

exedraj

> the builtin as ~~a builtin~~ an element

ftfy

DLosc

@emanresuA ===============]

(No joke, that was actually what my cat's paw just pressed)

emanresu A

:p

Dude coinheringaahing

@DLosc Don't believe you, I reckon you're the cat :P

DLosc

@Dudecoinheringaahing [shrug] Who knows? Maybe you're the cat. Maybe we're all the cat...

Bubbler

01:20

Lynn Lynn'd it again

rak1507

ok, how does that work

Dude coinheringaahing

œ? is "Permutation at index x of the items in y (where y defines the sort order of those items)"

rak1507

wtf

Bubbler

1st permutation is the list unchanged. 0th permutation is prev of it, which is entire list reversed. -1th is prev of that, which is entire list reversed, then last two elems swapped

Dude coinheringaahing

U then reverses that

Bubbler

01:22

Yes

rak1507

wow, that is insanely high iq

emanresu A

Jelly sus

Dude coinheringaahing

@Bubbler (Was in the middle of typing out what -œ? meant before you ninja'd me :P)

Bubbler

I did think of using œ? but didn't think of generating the reverse permutation

Dude coinheringaahing

Given that Jonathan Allan added œ? and it's 3 variations, yes, very high iq :P

œ¿, œ?, Œ¿ and Œ? :P

My headcanon is that he chose ? to indicate it's confusingness :P

Bubbler

01:24

:P

But yeah, using permutation index is so powerful at times

rak1507

someone smarter than me feel free to edit in a proper explanation rather than handwaving :P

Dude coinheringaahing

I'd suggest changing -œ? to be "-1th ordered permutation, i.e. second-from-last. This will always be the array reversed with the last 2 elements swapped"

Bubbler

Or you can quote my message verbatim :P

Lynn

if it helps humanize the events, I came here to say that I thought of U2œ?U first and didn't just look at it and think “oh duh, -œ?U”

rak1507

yeah yeah whatever 'I am definitely not an all knowing being' mhm sure

Dude coinheringaahing

01:30

That still involves going "How can I swap two elements? Oh, I know! œ?!" :P

Lynn

@rak1507 oh, the key word is, "This will always be the array reversed with the last 2 elements swapped"

(and then U un-reverses it again)

I'm totally gonna start telling people U stands for un-reverse

rak1507

lol

Dude coinheringaahing

It's "upend" IIRC :P

rak1507

@Lynn blame caird for that :P

Dude coinheringaahing

> This will always be the array reversed with the last 2 elements swapped"

rak1507

01:36

what

I copy pasted it

how did that happen

Dude coinheringaahing

Magic ¯\_(ツ)_/¯

You may have copied it in the 10 seconds before I added in the "reversed" :P

rak1507

lol, yep

Lynn

I wanna create this binary matrix and then matrix-multiply it with the input:

[1 0 0 0 0 0 0 0] [a]
[0 1 1 0 0 0 0 0] [b]
[1 0 0 1 0 0 0 0] [c]
[0 1 1 0 1 0 0 0] · [d]
[1 0 0 1 0 1 0 0] [e]
[0 1 1 0 1 0 1 0] [f]
[1 0 0 1 0 1 0 1] [g]

well, that didn't go well, but it's still readable

Bubbler

@Lynn I never expected out-of-range index to work there...

rak1507

I feel like I recognise that matrix

Bubbler

01:44

The matrix looks like a lower triangular checkerboard matrix with 2nd column repeated

rak1507

what is that from

oh, right, that solves the problem

Bubbler

-rot transform, obvs

rak1507

it looks suspiciously similar to something else I was doing a while ago

Lynn

you could start from [1, 0] and then iterate C,1 (in Jelly terms) to generate the rows

Dude coinheringaahing

@Lynn This is going to be like your Padovan answer, isn't it :P

Lynn

01:45

[1,0] [0,1,1] [1,0,0,1] [0,1,1,0,1] etc

rak1507

if you manage to outgolf me I will be extremely ~~annoyed~~ impressed

Lynn

then dot-product each of those with the input? I hope dot-product has the right behavior when one list is short, fingers crossed

Dude coinheringaahing

@Lynn You're already at 7 bytes at that point tho :/

@Lynn There are 2 dot products, that have different behaviours

ḋ pads with 0, æ. pads with 1

Bubbler

Maybe start with 0,1 and iterate with (Z with some dot)C and do U at the end?

ḋ should work at the very end

Lynn

probably the worst thing about this approach is that you need to specify the iteration count

Dude coinheringaahing

01:50

@Bubbler That's probably be shorter, as there isn't a digraph for 1,0 (superscript 5, D sometimes works, depending on the chain)

DLosc's answer is making me think this is somewhat Fibonacci-esque, and that ¡ has some crazy short dyadic link

Bubbler

An abomination trying to use base

rak1507

02:07

14 though, pretty short still

Bubbler

Actually 10

rak1507

wow nice

lynn is about to golf that down probably :P

Bubbler

Prefixes is OP

rak1507

so glad my first lesson tomorrow is at 1:45 not 8:30 so I can stay up golfing :P

Hello, World!

0

A: "Hello, World!"

Tarfish, 160 bytes x++++++++++++++++++++++++++++++++:+:+++++++++++:++++++++++++++++++++++++++++:.+++++++++++++++:++++++++++++++:.+++++++:::..+++:.{{{.{.{{.}}.:++++++.:.--------..; Tarfish is an esolang of mine that is a more tarpit-style version of ><>. This answer doesn't really use that much o...

emanresu A

02:15

Oh yes, that answer.

It's... verbose.

rak1507

you don't say

Lynn

this is 9: J>2C;¥\Ḋḋ tio.run/##y0rNyan8/9/LzsjZ@tDSmIc7uh7u6P7//…

rak1507

damn

nice one, wouldn't have thought of using a matrix product

Lynn

I guess I should post it

Bubbler

Go ahead

Lynn

02:32

codegolf.stackexchange.com/a/233671/3852 why did I type all that it's 4am

rak1507

nice answer

ohh J>2 that is clever

Dude coinheringaahing

On mobile, so I can't try it, but could you replace >2 with ’ and C with vectorising logical not?

Or would that mess up the first row?

exedraj

You mean J’¬;¥\Ḋḋ?

Try it online!

Lynn

if you read the rows backwards, as binary numbers:
1, 110, 1001, 10110, 101001, 1010110, ...
1, 6, 9, 22, 41, 86, 169, ...

a formula generating those numbers is `floor(pow(2,k)/3) xor 3`

but J‘2*:3^3BUḊḋ is pretty long

@Dudecoinheringaahing I need the actual 1s because they are the right arguments to ; in the scan

DLosc

@Lynn Which also happens to be the output for the fourth test case.

Dude coinheringaahing

02:45

@Lynn :(

CMC: Create a Jelly program that never halts. You may not use any quicks. Shortest wins

Segfaults due to infinite recursion (e.g. no TCO) count as halting. You should hit the 60s timeout on TIO

hyper-neutrino

i think 9!!! works lol

wait, you can do like ⁹!!

Dude coinheringaahing

That will halt tho

exedraj

@Dudecoinheringaahing I have a very boring 13 byter

hyper-neutrino

oh wait, i misread it as just that it should hit 60s lol

Dude coinheringaahing

@exedraj Eval as Python?

exedraj

02:55

;p

Dude coinheringaahing

Fair enough, but I bet there's a pure Jelly way :P

v keeps segfaulting on me

exedraj

I got it down to 10 bytes with string compression

7 bytes kinda using quicks but not in the main program: “1 1¿”V

hyper-neutrino

lol bruh

exedraj

“ƬÄ¡ṾEı» for 10

no wait

I forgor the eval as python part

hyper-neutrino

well if you can cheat with quicks like that then just do ”ÇV

exedraj

02:59

lol

Browncat Programs

03:11

I really don't know why my school has five spanish teachers, a sign language teacher, and no french, german, italian, or japanese

DLosc

Because Texas?

Sounds pretty reasonable for a U.S. state adjacent to Mexico IMO.

Browncat Programs

Seems like there could be slightly more options though :/

DLosc

True. Maybe change out one or two of the Spanish teachers for something else.

exedraj

@BrowncatPrograms budget funding issues?

Browncat Programs

I doubt it

exedraj

03:27

Lack of specialisation?

Browncat Programs

Oh hey, I'm starting to get email spam from actually good colleges for once

Bubbler

Ooh nice

DLosc

Top Ten Reasons You Should Attend MIT! Number Seven Will Shock You!

Browncat Programs

03:42

I'm aiming to go to a college somewhere around the top 20, since most of the ones higher than that that I've looked at don't accept many AP tests

exedraj

04:45

I've found more suffering for everyone

PyGamer0

Even me wtf

exedraj

not funny didn't laugh

the video I linked is actually cursed

PyGamer0

@exedraj yes it is

@exedraj well for me it was pretty funny

hyper-neutrino

@exedraj wtf

exedraj

@hyper-neutrino yes

hyper-neutrino

04:50

i am going to go listen to the original song to attempt to clean my mind of this ungodly eldritch horror

exedraj

@hyper-neutrino use soulless 4 as mind bleach instead

PyGamer0

oh hyper's back in his λ form

Me: Looks at ngn/k's implementation to learn how reshape works.
Also Me: Looks pretty readable: https://codeberg.org/ngn/k/src/branch/master/h.c

it looks liek an esolang; i cant understand anything except the include header

oof there is like 50 macros defined

Adám

This is the way of Arthur Whitney.

PyGamer0

CMC: Given a list of 9 numbers, reshape it to 3 by 3 matrix. Don't use reshape builtins

Bubbler

Define builtins

Adám

05:00

Any builtins?

Bubbler

Jelly: s3, split into chunks of 3

(Jelly does not have reshape in the APL sense)

exedraj

@PyGamer0 Vyxal: 3ẇ

(we don't have reshape in the APL sense either)

PyGamer0

@exedraj split into 3 chunks?

exedraj

chunks of 3

PyGamer0

> `s` Split into chunks
`#` Reshape (APL/k)

^ which is more useful?

exedraj

05:05

@PyGamer0 but if you want something more fun: 0 3"3 6"6 9"Wƛ?ni

@PyGamer0 both

PyGamer0

@exedraj what does that do?

@exedraj nice

exedraj

@PyGamer0 input[n] for n in [[0, 3], [3, 6], [6, 9]]

because indexing a list with a list treats the index as a python slice

PyGamer0

look in the flags :P

exedraj

yes I saw that

very cool

PyGamer0

@exedraj i updated the flags

exedraj

05:11

very good

PyGamer0

05:32

CQ: CLike Structures in esolangs?

Adám

@PyGamer0 ⎕⊂⍨9⍴3↑1 in APL then?

Bubbler

When a language properly supports declaring and using C-like structures, it is no longer an esolang

If you remove the "declaring" part, it just becomes a tuple

PyGamer0

> it is no longer an esolang

???

Bubbler

which can be simulated relatively easily in many esolangs

PyGamer0

05:58

how do i implement (APL's) reshape in python?

ngn

@PyGamer0 k6 has that as (0N;n)# or (n;0N)#, in k9 it's n^

Bubbler

06:09

@PyGamer0 First adjust the length of the list of elements, then split into chunks from the last axis to the first

PyGamer0

06:22

Try it online!

@Bubbler ^ gtp3 with my modifications

doesnt work like ⍴

also horribly breaks on higher axis

hyper-neutrino

wdym breaks on higher axes it doesn't even work on your sample case

your list comp is definitely wrong; your loop should either have a step argument or you should be multiplying i by the interval size

PyGamer0

> your list comp is definitely wrong; your loop should either have a step argument or you should be multiplying i by the interval size

not mine

that is generated by gtp3

in The Edge of Propinquity, 12 mins ago, by exedraj

def reshape(shape, l):
    if len(shape) == 1:
        return l
    else:
        return [reshape(shape[1:], l[i]) for i in range(shape[0])]

exedraj

in The Edge of Propinquity, 12 mins ago, by exedraj

apparently

hyper-neutrino

well that's impressive for something made up by a computer then

it's still totally wrong but like. it's sensible enough that it didn't look immediately blatantly dumb

exedraj

It's the codex model

Trained on open source

Same stuff that powers copilot

hyper-neutrino

06:30

aight i think this works? idk tho

Bubbler

Yeah, that's pretty impressive for machine generated code. It got the basic approach (almost) correct after all

PyGamer0

@hyper-neutrino yes it does thx

hyper-neutrino

lol, nice

to be clear there's almost certainly a much more intelligent way to do this

than to turn the list into a deque and just keep rotating it

but i am too lazy and it is 2:40 AM

PyGamer0

its fine for now

Bubbler

06:47

@hyper-neutrino Sounds like itertools.cycle

PyGamer0

07:59

how do i make reduce_first(

as a complement to this

Bubbler

@PyGamer0 Your reduce is actually reduce_first I think

PyGamer0

@Bubbler oh yeah

so how do i do reduce?

Bubbler

08:17

@PyGamer0 Recurse until you've got a list of numbers, then reduce on it

Adám

@PyGamer0 Implementing APL?

PyGamer0

@Adám no

actually i might do that in the future

but not now

@Bubbler is this it?

now i need vectorise1( vectorise2( vectorise3(

i think i will copy that from vyxal or something

@exedraj why is there a custom vy_zip(?

where is jelly's generic vectorise function?

exedraj

08:40

@PyGamer0 because normal zip doesn't pad shorter iterables with 0

Bubbler

@PyGamer0 Looks good

emanresu A

Golfing = 'economizing characters

PyGamer0

@exedraj you can use itertools.zip_longest

Try it online!

emanresu A

The wikia has someone called 'redwolf'. Who's that, never heard of them ;p

one 3 too many

LEEET

PyGamer0

08:57

dyadic vectorisation done

@emanresuA 1+3+3+3+7 = 17 which is prime

emanresu A

True

PyGamer0

@emanresuA and oeis

@PyGamer0 and monadic also done

emanresu A

09:13

Good job

PyGamer0

ty

Fun Fact: I made all the functions in tio.run first before copy pasting them.

emanresu A

That's actually quite a good idea :p

emanresu A

11:32

Better than bogosort - gobosort!

Which sadly hasn't been created yet

Dude coinheringaahing

11:43

@Bubbler It has mold, which is similar :P

pxeger

> Jelly
> mold

@Dudecoinheringaahing is that deliberate? :Þ

emanresu A

No, Jelly's moldy.

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