The Nineteenth Byte

sure, no doubt they got plenty of data from spying peoples' devices without their consent

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Q: Is it a perfect loop?

Your task is to take a GIF or an animated image in any reasonable format as input (including taking the file name of a GIF in the current directory), and output whether it is a "perfect loop" - that is, the frames transition seamlessly from the end to the start, and a human cannot notice where i...

RIP perfect loop challenge

Let's try to define it, although it is hard.

7:30 PM

the broadness is on the word "seamlessly"

what would be "seamless" for someone could be "not seamless at all" for somebody else

yeah and now that i think about it

comparing the last and first frames seems good

so the challenge may have different perceived definitions by different people

@Okx I'd say that a "perfect loop" is a GIF whose frames transition identically from the end to the start as well as start to end.

@EriktheOutgolfer just because you're unaware you gave consent doesn't mean you didn't give consent

@NewMainPosts 12 comments in 10 minutes :P

7:31 PM

;)

but i need a an artifical test case where it is an almost perfect loop but shifted around a few frames to trick the computer maybe

@Poke I don't think that EULAs and such include that they're "spying you" though?

Anonymous

@Okx IMO, the best way to define it would be that the first and last frames have a dssim score under some threshold

@Okx That's your problem bro :-)

~~it is a perfect loop if i say it is~~

7:32 PM

@Okx what I recommend is setting some threshold

@EriktheOutgolfer Well of course they wouldn't phrase it that way

@Okx That's such a "new user" thing to say :P

Anonymous

@Okx Three dashes

like, some fraction of the total number of pixels

also you don't need to shout :p

it's just serendipitous for them that they get that information

7:33 PM

@Poke maybe "data collection" would be a way to phrase it

yeah the challenge sort of works more if i define it subjectively

and also

I'm sure there's a "data collection" clause somewhere

haha

reddit picked not me

so yes we can define it objectively

"Images corresponding to a truthy value have been taken from /r/perfectloops and for falsy test cases, /r/almostperfectloops and /r/gifs."

CMP: Which challenge proposal should I work on, "Is it a valid chess move?" or "the one to do with building a string compressor"?

Anonymous

We need objectivity here :P What about GIFs that aren't in either subreddit? What about GIFs that are incorrectly submitted to the respective subreddits?

7:34 PM

@Poke but I'm pretty sure that clause only talks about stuff you can disable otherwise they would lose potential clients who do actually read stuff carefully

Anonymous

@cairdcoinheringaahing First, though it might be a dupe

ಠ_ಠ I had [tag:asci-art] instead of [tag:ascii-art] on my profile

Anonymous

@Mr.Xcoder [tag:oopsie]

Maybe we can set a threshold of 100 upvotes @Mego

@EriktheOutgolfer You can almost certainly disable some of it. If you look through the windows 10 settings almost all of the telemetry stuff can be diabled

etc

and i'm sure they do lose clients because of stuff like that

but you might overestimate the number of people who read and care enough

Anonymous

7:36 PM

@Okx That's still subjective. The mass quantities of bots on Reddit can easily sway the score. Also, the challenge shouldn't be reliant on an external site.

what do i do then lol

determining if a gif loops is completely subjective

that's why i think it makes a good challenge but other disagree

the problem is, too broad is too broad

you're venturing into popcon territory

have fun arguing with half the site

Anonymous

7:37 PM

@Poke No, it isn't. You can do it objectively (though the objective criteria may disagree with human subjective opinion)

^^^ ^^^^

but the thing is if you define it objectively it's easy to get 100%

Anonymous

I think it could be a good challenge, but it needs objectivity

@Mego Can you provide an example

Anonymous

@Okx Then why not just make it code golf?

Anonymous

7:38 PM

6 mins ago, by Mego

@Okx IMO, the best way to define it would be that the first and last frames have a dssim score under some threshold

@Mego I've looked for dupes (read: searched the entire chess tag), and this was the closest I found. FWIW, the base of that challenge is Given a list of 16 elements, each consisting of 4 elements, and a second list with 4 elements, determine whether the move detailed in the second input is a valid chess move.

eh, note sure about that

@Mego agree

it was meant to be not code golf from the start lol

@Mego so if i make a gif that just replaces the last frame with the first frame, that would be acceptable to you

7:39 PM

I wouldn't make it code-golf either

Anonymous

@cairdcoinheringaahing If you're doing it in the context of the entire board, then I agree that it wouldn't be a dupe

@Mego How about if the first and last 5 frames are similar enough?

you would have to do that for every frame in the gif

which is stupid

@cairdcoinheringaahing ...

> define "similar enough"

Anonymous

@Poke That's fair. Maybe requiring some dssim threshold between every pair of adjacent frames (including last and first).

7:40 PM

Just get a much larger number of test cases, define it objectively and enforce a size restriction, and I think it'll be very well received.

the problem is that the cut in it can maybe be halfway through the loop

@EriktheOutgolfer Within a threshold given by Okx

and then first and last X frames will be useless

@Mego what about a gif that doesn't illustrate motion? like a traffic light

Anonymous

@Poke Then the score will be very nearly 0 for every pair of frames... I see what you mean

Anonymous

7:42 PM

Well, the challenge is about seamless loops, so gaps in the middle aren't really relevant. I guess the way to do it would be to look at the last N frames and the first N frames, and see if that is "smooth"

by my current subjective definition, the cut can be in the middle and count as not perfect

i want to keep that

I think you still run into the issue with the traffic light

my subjective definition works

@Okx then define as both between the frames and between last and first frame?

unfortunately it needs to be made objective

Anonymous

7:44 PM

@Poke Yeah, but that can be managed with an appropriate threshold. Finding a threshold that is sensitive enough to detect perfect loops but not so sensitive that it rejects some less-smooth loops will be difficult

maybe if the range of the differences between all of the consecutive frames is high enough might work

I think if the challenge is going to work you'll need restrictions of what can be in the gif

Anonymous

That gives me an idea. What if the threshold is dynamic, and based on the frames around the beginning and end?

CMP: Assuming you were capable of doing anything (within reason) on this site, what one thing would cause you to say "That's code golfing done, time to stop"?

@Poke subjective

7:46 PM

and another idea would be to make it levenshtein-like

@cairdcoinheringaahing Winning (or tieing) all challenges.

Anonymous

@cairdcoinheringaahing I don't know anymore. At one point, I would've said Tetris in GoL...

Mine is probably have a challenge which no-one is able to answer, but is provably possible to be done

@Okx Maybe I'm misunderstanding but I thought we were throwing subjectivity out the window

@cairdcoinheringaahing making a quantum bot that develops a code golf language that evolves automatically based on the challenges posted and automatically posts the shortest solutions possible in that language

7:47 PM

The closest example to this challenge that I can think of is codegolf.stackexchange.com/questions/71631/upgoat-or-downgoat

> Please don't hardcode. It's boring, I can't enforce it completely but I can ask nicely.

@cairdcoinheringaahing Analyzing all existing challenges and creating a golfing language that uses Huffmann encoding to have the shortest overall solution to everything.

Anonymous

@cairdcoinheringaahing That's simple. "Given an SHA3-512 hash, output a binary string with that hash."

i'm not sure how that got past, because you can't define it obectively really

but it's easy to see subjectively

There was a set of test images that had a known result

@Mego That's really easy. Unfortunately the program takes a while to finish.

7:48 PM

@Mego ಠ_ಠ As in like Tetris GoL, but even harder

@Poke can i do that for my challenge?

and your answer got a score based on how many results your code got correct

@Mego I think that would simply be some brute force?

like, np-complete

@Okx I'd defer to Mego and others for that

Anonymous

@EriktheOutgolfer Sure, but it would be impossible to verify solutions

7:49 PM

I don't want to be the one to make the call on that

@Mego Why? Just count up and test each.

Anonymous

@Poke That's basically test-battery. There's a big pitfall, though: it can be very easy to get 100% if the test cases aren't chosen well.

@Mego but you can just increment the binary strings ("", "0", "1", "00", "01", etc.) until you find one with the right hash

Anonymous

@EriktheOutgolfer Eh, that's fair

so in fact if you can implement the sha3-512 algo or import it it should not be very hard

Anonymous

7:51 PM

Alright, new "impossible" challenge idea: "Prove or disprove the Collatz conjecture fastest-code"

@Mego That's easy, just have an infinite while loop :P

>solutions must terminate

umm, nope?

Anonymous

@cairdcoinheringaahing But you wouldn't be able to score it without proving or disproving the Collatz conjecture, which would be far too great of a task for a PPCG challenge

by virtually never terminating you don't either prove or disprove

ATaco

7:53 PM

Mr. XCoder keeps golfing my own language :P

by actually never terminating you prove but then you must prove your program never terminates so basically you are left to prove it yourself

Did you figure out your stickers yet, @Mego?

Anonymous

@Okx That wouldn't be necessary to add. An infinite loop solution would have an infinite time, so the score would be infinitely poor, running afoul of the serious contender rule.

AdmBorkBork

Output: $true, almost surely accurate.

Anonymous

@Mithrandir Nope. I haven't been contacted by the overlords in any fashion

7:55 PM

Chess Q: If a pawn hasn't moved, is it allowed to take a piece as though like a knights move? Like this?

Anonymous

@cairdcoinheringaahing No - it is never allowed to do that

@cairdcoinheringaahing why would it

@Mego nothing on Twitter?

i wander what "no moving pawn" chess would be like

@EriktheOutgolfer Move forwards two, and take the piece

7:56 PM

Should I ping Shog?

@Okx A knight battle

Anonymous

There are four valid moves for pawns. The first is simply advancing forward one square. The second is the double move, advancing forward 2 squares, which requires that the pawn hasn't moved prior to the double move. The third is en passant, which has a much more specific set of requirements. The fourth is diagonal capture.

the fourth is moving diagonally or anti-diagonally forward to a capture

AdmBorkBork

Isn't en passant only for capturing opposing pawns?

Anonymous

@AdmBorkBork Yes iirc

7:58 PM

@Mego Yeah, I was just checking. I know how to play chess, but have never seen that situation come up before :P

En passant

En passant (from French: in passing) is a move in chess. It is a special pawn capture that can only occur immediately after a pawn makes a double-step move from its starting square, and it could have been captured by an enemy pawn had it advanced only one square. The opponent captures the just-moved pawn "as it passes" through the first square. The result is the same as if the pawn had advanced only one square and the enemy pawn had captured it normally. The en passant capture must be made on the very next turn or the right to do so is lost. Like any other move, if an en passant capture is the...

> pawn capture

Anonymous

@Mithrandir I don't think that's necessary yet. If I don't hear from someone in a week, I'll make some noise.

@Mego I guess penguins really like stickers...

@Mego it's fun pinging Shog though... :P