The Nineteenth Byte

Anonymous

00:00

Glad to help :)

New Main Posts

01:05

0

Q: Test the endianness

Given a UTF-16 string, test its endianness. Rules: As long as the input is in UTF-16 without BOM, its type doesn't matter. In C++ on Windows, it can be std::wstring or std::u16string. In Haskell, it can be [Int16] or [Word16]. The endianness is tested by noncharacters. If the input contains a ...

PhiNotPi

02:32

What is the most complex language for which you can compute the exact time complexity for any program/algorithm in the language?

LOOP (programming language)

LOOP is a programming language designed by Uwe Schöning, along with GOTO and WHILE. The only operations supported in the language are assignment, addition and looping. The key property of the LOOP language is that the functions it can compute are exactly the primitive recursive functions. == Features == Each primitive recursive function is LOOP-computable and vice versa.In contrast to GOTO programs and WHILE programs, LOOP programs always terminate. Therefore, the set of functions computable by LOOP-programs is a proper subset of computable functions (and thus a subset of the computable by WHILE...

Sriotchilism O'Zaic

@PhiNotPi I suspect that one does not exist.

PhiNotPi

There's this but it's actually too advanced. You can put an upper bound on time complexity though.

El'endia Starman

"What is the most complex language" oh boy, probably gonna be something suuuper complex "can compute the exact time complexity for any program" oh, probably something super simple.

PhiNotPi

I suspect it might be possible in a version of LOOP with only addition but no subtraction.

The issue with subtraction is that it's possible with have one variable of magnitude O(something big) and another variable with magnitude O(same big thing) but still have the difference between the variables be O(small).

Sriotchilism O'Zaic

Is there a proof that we cannot find the time complexity of algorithms in LOOP?

Oh wait I see.

Oh wait no I do not see.

Ok I think I have a proof that no such language exists.

PhiNotPi

02:40

people.csail.mit.edu/meyer/meyer-ritchie.pdf

El'endia Starman

@SriotchilismO'Zaic Define "language" (maybe that's a question for @PhiNotPi).

PhiNotPi

Here's a paper where they talk some about forming an upper bound but that "The complexity problem for Ln is: given a program P in Ln determine whether Tp is bounded by f,_l (k) for any integer k. Theorem 6. For each n > 3, the complexity problem for Ln is effectively undecidable. "

Sriotchilism O'Zaic

Sorry I mean model not language.

PhiNotPi

The LOOP language can compute exactly the primitive recursive functions. (According to PPCG's slightly arbitrary rules, anything less powerful isn't considered much of a language at all.)

Sriotchilism O'Zaic

Oh my proof does not work.

Wait hold up, how are we defining time complexity over an abstract model?

What is to stop a model from "running in constant time" over every function?

El'endia Starman

02:47

@SriotchilismO'Zaic That's an oracle machine.

Sriotchilism O'Zaic

Yes and what is to prevent that machine?

El'endia Starman

Simply say that the language must be executable by a Turing Machine. :)

Sriotchilism O'Zaic

Ok what is to prevent a oracle machine that only computes computable functions?

El'endia Starman

...that's just a Turing Machine?

Sriotchilism O'Zaic

No the Oracle machine takes constant time to compute every function while the Turing machine does not.

PhiNotPi

02:52

Well with the LOOP language, it's essentially a question of how does the count of basic operations (starting a loop iteration, an addition, or an assignment) scale as the input numbers to the program scale.

El'endia Starman

In any case, I think it suffices to require the language to be executable by a TM. Oracles can do them in constant time, yes, but that's not "executable by a TM".

Sriotchilism O'Zaic

@El'endiaStarman I'm not sure what you mean by this?

@PhiNotPi This certainly makes sense, but once we get to more abstract edge cases, for example making each computable function a basic operation, I feel like we need a concrete definition.

PhiNotPi

And since you don't care about multiplicative factors when determining time complexity, figuring out the time complexity boils down to... if I double some of the input variables, how many more times do the bodies of the innermost loops have to be run?

Sriotchilism O'Zaic

Should we maybe define time complexity in terms of the complexity of an equivalent Turing machine?

El'endia Starman

@SriotchilismO'Zaic Phi's question was "what is the most complex language with computable time complexity for all programs?" and it's easy to require that such a language must be possible to implement with a Turing machine. An Oracle explicitly can do more than a Turing machine, and so are disallowed. Even if you restrict what the Oracle can compute, it's still not implementable with a TM because the TM does not have a magical oracle to ask.

PhiNotPi

02:58

I don't know if we need to get this abstract? Unless we want to talk about computers that operate wildly differently than everyday computers, which I wasn't planning to get into. Because I think time complexity seems well-enough defined by saying addition/assignments are the basic unit operations.

Sriotchilism O'Zaic

Well if we do say time complexity is in terms of the equivalent Turing machine then there is no most complex model and my proof does work.

I think that we can show that the addition, subtraction, assignment definition of complexity is equivalent to the Turing machine definition.

The proof goes like this: Let us say that we have a model M which is the most complex model that can compute its own complexity. Let us take the set of functions computable by a Turing machine but not M (this must not be empty since it is weaker than a TM) and choose an arbitrary function from the list, f. Let us then make a new model M' which is identical to M except that it is augmented with a new atom which computes f.

This new model is more complex, since M could not compute f, but can still compute its own complexity, since the complexity of f is computable.

This is a contradiction since we started by saying M was the most powerful model that could compute its own time complexity and M' is more powerful, thus no most powerful language can exist.

El'endia Starman

I think "a new atom which computes f" is what hides all the extra complexity.

Sriotchilism O'Zaic

What do you mean by that?

El'endia Starman

That's simply not a thing you can do with a Turing machine.

Sriotchilism O'Zaic

Yes it is?

It does not need to compute f in constant time.

It just needs to compute f.

El'endia Starman

03:11

No, it isn't. Turing machine: read symbol, write symbol, move head left, move head right, change state, and halt.

Sriotchilism O'Zaic

f is explicity a Turing computable function ?

El'endia Starman

Ah-ha, there's the extra complexity.

Sriotchilism O'Zaic

I'm not sure what is meant by "extra complexity"?

El'endia Starman

If you pick a function outside a given complexity class and include it as an "atom", then all programs are now in that complexity class.

Err, rather, the language is.

Sriotchilism O'Zaic

Yes, that is why M' is more powerful than M.

El'endia Starman

03:13

So you can't say "pick an arbitrary function f" and claim that the language didn't get any more complex.

Sriotchilism O'Zaic

The language did get more complex, that is the point.

El'endia Starman

Okay, different tack.

9 mins ago, by Sriotchilism O'Zaic

This new model is more complex, since M could not compute f, but can still compute its own complexity, since the complexity of f is computable.

The complexity of addition, assignment, and looping are all computable and simple, but their combination in the LOOP language is not necessarily so.

Sriotchilism O'Zaic

Ah I see

I need to explain what is meant by adding atom

Let us say that M is defined by grammar where S is the start symbol.

El'endia Starman

Go on ahead. :) Meanwhile, my wife is pressuring me to head to bed, so I'll say g'night now and read your messages in the morning. :)

Sriotchilism O'Zaic

goodnight!

The grammar for M' is S' := S; S' := A; <the grammar of M> where A is the new symbol for f and S' is a new start symbol.

This adds exactly one new program, that computes f.

f cannot be used in tandem with previous programmes

Feel free to ping me if you are reading this tommorrow and you are having a question or issue with my proof. This is interesting stuff.

New Main Posts

06:11

0

Q: Print the sequence

21, 21, 23, 20, 5, 25, 31, 24, ? Inspired by this Puzzle, given an integer \$n>0\$ , print out the following sequence until you reach a non-Integer (spoilered, in case you want to solve the puzzle yourself first) TestCases: Input and Output may be taken in any reasonable format, standard l...

code-golf

Cows quack

08:09

rule30prize.org

5

Anush

08:52

hi all

ngn

@Anush hi one

Anush

:)

I am thinking of a new coding challenge.. fastest-code I think

flawr

09:07

in Primes and Squares, 46 secs ago, by flawr

Does anyone here know a simple GUI library for python? I want to do something that allows you to display images and draw on them - but I'm not familiar with building GUIs in python. I also considered doing the GUI in HTML/JS but again I have no experience with building a python webserver:)

ngn

09:21

@flawr gimp not good enough?

flawr

@ngn Isn't that really complicated to access wtih python?

ngn

@flawr it has an api, idk much about it, i think it's in the other direction - gimp calls your py code

search for "python-fu"

flawr

09:44

well gimp is probably way to powerfull for what I need

I maybe should have specified: I really only need to draw one color (black/white) with the mouse, maybe adjust the radius of the "brush" or something like that, which wouldn't be too difficult to implement anyway

Anush

10:20

I was thinking of posing a fastest-code challenge around oeis.org/A161169 . But to make it more interesting I am dividing by the max possible and the code only has to output correct to three decimals places. Like this bpaste.net/show/Ygsg

it is worth trying with larger values of n

John Dvorak

Would a Monte Carlo algorithm be valid for that challenge?

Anush

@JohnDvorak sure! It just has to output the right answers up to 3 decimal places

I am wondering two things

a) what the output should be? I mean outputting all the values for k in range(int(n*(n-1)/2+1)) is quite a lot and b) if I should just give a score being the speed relative to the python code to make it easier for people to judge for themselves

any thoughts?

Anush

10:40

how do I find the sandbox?

@flawr PyQt ?

@flawr or pygame?

Sherlock9

I've not completely read through all the mess of the past week because I've been dealing with my own troubles closer to home (look up Indonesia parliament protests) and at time of writing I'm at work, but I want to thank Dennis deeply for his years of service, first and foremost, and thank the other mods for theirs and their continued support despite this shitstorm.

Second and thirdmost, the Discord server is open, if a bit dead, and the CGCC gaming Discord server is also open and less dead.

Fourthmost, I haven't seen all the discussion around Axtell and its hiatus but if there's any way I can help with development now that I have a more stable situation post-university, I'd love to help. I know we have unresolved issues with what this sort of community migration/reboot/backup would entail, but frankly now seems like a good time to start hashing out those issues and continuing to develop a "backup" plan

ngn

11:19

which reminds me, has anyone ever tried to back up tnb's chat log?

flawr

@ngn I'm not sure whether it uses a backup but @El'endiaStarman made the The Nineteeth Byte Data Explorer

@Anush go to codegolf.SE and click the link in the top right yellow box

ngn

@flawr looks like it works with real-time data

Anush

@flawr thanks. Good gave it to me in the end

flawr

@Anush have yo used any of those?

Anush

@flawr sadly no, sorry

New Sandboxed Posts

11:37

0

A: Sandbox for Proposed Challenges

Compute A161169, approximately and quickly Input: Two values n and k. Output: T(n,k)/n! rounded to three decimal places. T(n,k) is defined by OEIS sequence A161169. questions For fastest-code, what should the input and output be?

Anush

12:38

hi @Adám

Adám

@Anush Hello Anush

Anush

@Adám thanks for your comment on my sandbox question. The thing I am not clear about is what the input and output should be exactly. I mean to be a fastest-code competition I think I need to say somethign like "the largest n,k you can reach in 10 seconds"

does that make sense?

Adám

@Anush Well, we should have some sample n,k with expected result, just to check our implementations.

Anush

@Adám yes I can definitely do that

@Adám but what should the actual task be in terms of input ?

that's what I am not clear about

I could ask for all T(n,k) for a fixed n but that's a large output

Adám

@Anush fastest-code is very difficult to pull off. How will people time their solutions? It'll require everybody to have access to the same hardware.

Anush

12:44

@Adám I think there are two options. a) I time them all on my machine. I don't mind doing that

or b) I give them test code and they give a factor improvement over that

Adám

@Anush Do you have all programming languages available?

@Anush Test code?

Anush

@Adám anything that runs on linux and is free

I can't do mathematica

Adám

Or Matlab.

Anush

true

Adám

@Anush Btw, you should also define T(n,k) in your challenge, so people don't need to rely on external info.

Anush

12:46

@Adám will do

Anush

13:09

@Adám what do you think now? codegolf.meta.stackexchange.com/a/18145/9207

Adám

@Anush Much better. I personally dislike ASCII pseudo-maths. Maybe go MathJax for the formulas?

I can do it for you if you're not comfortable with MathJax. (It is easy though.)

Anush

@Adám That would be very kind! Thank you

Adám

@Anush OK, editing, hang on…

Anush

thanks

Adám

@Anush Done. Feel free to edit, of course. Oh, and you need to move the hyperlink out of your title.

caird coinheringaahing

13:28

@Anush For fastest code questions, you need very detailed specifications on how the speed of the code will be measured. For example, if its on your machine, specs should be included (i.e see here)

Anush

@Adám thanks and done

@Adám I will add the specs.. but I am not still not clear what I am asking for input and output

Anush

13:44

let's play, guess that function.. any guesses for imgur.com/a/GraYmCH ?

ngn

Veskah

f(420x)

AdmBorkBork

@ngn I tried to y=1/x and broke my arm. Now I'm gonna sue you.

ngn

@AdmBorkBork /r/funny is to blame :)

Veskah

@AdmBorkBork You're probably fine for y=-|x| still

New Main Posts

13:59

1

Q: From Plate to State

This is essentially the inverse of Generate a US License Plate Challenge: Given a string that matches one of the below license plate formats, output all possible states that match that formatting. In the below table 0 stands for a single digit 0 through 9 inclusive, and A stands for a single let...

code-golf string kolmogorov-complexity

Anush

14:21

@ngn thanks! Is there some general to explore the options?

ngn

@Anush a general method to enumerate functions?

Anush

@ngn I meant to try out functions to see how well they fit data. But actually I did it by hand :)

it's the second one from the left on the top row

ngn

there are many kinds of interpolations

Anush

yes.. just trying the 15 in the picture would be a good start

dzaima

@Anush well there's always wolframalpha but it doesn't like approximate inputs

Anush

14:41

@dzaima thanks. That's interesting

El'endia Starman

@flawr and @ngn: TNBDE ostensibly has backups in the form of automated database dumps, but it should have every single non-deleted message, possibly excepting the previous one or two hours.

ngn

@El'endiaStarman i already downloaded the history throught the api, but those dumps might be worth looking into as well

93min, 43MB of messy json

El'endia Starman

Huh, it took far longer for me to download the whole chat history. I probably have a few more pieces of information than you do.

ngn

mine is just many lines of the form {"event_type":1,"time_stamp":...,"content":"...","user_id":..,"user_name":"...","room_id":240,"message_id":...},

El'endia Starman

I presume you just downloaded the whole transcript for each day? One request per day?

ngn

14:52

@El'endiaStarman no. i request a batch of many messages, starting from the current time backwards, i look at the earliest message in the batch, and request again using before: in the new query, and repeat

El'endia Starman

Ahh I gotcha.

What's the precision of the timestamp you have?

IIRC it might be minutes? (@ngn, check out the edit history of this message.)

flawr

@Anush f(x) = 1000 * (x/70)^2?

Anush

@flawr oh that's good

ngn

@El'endiaStarman here's a sample message:

El'endia Starman

@El'endiaStarman I mention this because I remember having an issue with the timestamp being missing for most messages.

ngn

14:55

{"event_type":1,"time_stamp":1570015148,"content":"which reminds me, has anyone ever tried to back up tnb\u0026#39;s chat log?","user_id":136283,"user_name":"ngn","room_id":240,"message_id":51932959},

El'endia Starman

Do you get number of stars for messages that have them?

ngn

@El'endiaStarman yes:

{"event_type":1,"time_stamp":1570003786,"content":"https://www.rule30prize.org/","user_id":152262,"user_name":"Cows quack","room_id":240,"message_id":51930797,"message_stars":1},

El'endia Starman

@ngn Sweet. What about whether the message was edited or not?

ngn

@El'endiaStarman yes:

{"event_type":1,"time_stamp":1570008088,"content":"@flawr \u003ca href=\"https://en.wikipedia.org/wiki/GIMP\" rel=\"nofollow noopener noreferrer\"\u003egimp\u003c/a\u003e not good enough?","user_id":136283,"user_name":"ngn","room_id":240,"message_id":51931665,"parent_id":51931496,"message_edits":1,"show_parent":true},

i was a bit worried about flooding the server or getting banned, so i spaced the requests a few 10s of milliseconds apart, but that seems to have been unnecessary

El'endia Starman

Cool. I'm just trying to think of anything I have that you don't. Hmm...what about the Markdown contents? I.e. this message will have <em> or something similar in the content field. But the Markdown contents will have asterisks.

ngn

15:02

so it should have taken slighly less time

@El'endiaStarman i think those are those ugly \u escapes in the json strings

El'endia Starman

Eh, I most definitely got rate-limited when I was scraping the transcript. Granted, I was also fetching each message individually as well (for the timestamp).

ngn

@El'endiaStarman ah :) well, that's a lot of requests

i fetched them in batches of 500 - it seems to be the max

El'endia Starman

Yeah. Making my scraper robust to SE rate-limiting and memory limits on the remote server I'm using was by far the hardest part. Probably took 3x as much time as everything else put together.

Fortunately, that robustness did pay off; I haven't had to touch TNBDE in literal years and it's still chugging along.

ngn

cool. so, backup has been settled in two different ways.

El'endia Starman

Does Axtell have any chat functionality?

ngn

15:12

@Mego ^

dzaima

@El'endiaStarman afaik they decided discord/some other proper chat platform would be enough

El'endia Starman

Reason I ask is that if we built a chat platform as well (which is itself a monumental task), then we could import TNB's chat history into that. And I'd want stars and up(/down?) votes on messages. Right now, stars get used for both "this is important" and "I agree with this".

....and for lulzy reasons, but let's not encourage those.

caird coinheringaahing

@El'endiaStarman I definitely agree with up/down votes on messages. There have been quite a few messages I've wanted to show my disagreement with without having to say anything

DJMcMayhem

@El'endiaStarman The way I see it, Stars are "This needs visibility", and reactions could be used for up/down votes for polling

Although reactions are not usually anonymous in most clients I've used. Whether that's a pro or a con, I'm not sure

ngn

many seem to believe that starring a message brings some benefit to the person who posted it

Poke

15:20

anyone well versed in oauth2

DJMcMayhem

Stars brings a warm fuzzy feeling to the person who posted it.

8

caird coinheringaahing

@ngn Tbf, I'm always a little happy if one of my messages is starred

Little thing to brighten up my day

flawr

clearly stars > rep

ngn

@DJMcMayhem that is true :) i mean, they believe it's reputational benefit

DJMcMayhem

@flawr Oh, absolutely. I'd trade all of my rep for 40k stars in a heart beat :P

Especially since I wouldn't lose any privileges lol

El'endia Starman

15:21

@DJMcMayhem Ah yes, reactions are much more expressive, this is true.

flawr

why not?

caird coinheringaahing

@flawr I'll agree with that after I get to 10k :P

flawr

@El'endiaStarman would be fun to be able to star what someone said IRL:)

@cairdcoinheringaahing you have to measure it in km, not miles and you'd get there quite a bit quicker:P

DJMcMayhem

@Cowsquack That's really cool

caird coinheringaahing

@flawr I prefer measuring in parsecs. Gives me a real goal to aim for :P

flawr

15:25

haha

DJMcMayhem

@flawr Hey, I just saw on Goodreads that you've read Elantris also. I just finished it :)

El'endia Starman

@DJMcMayhem A couple of my coworkers made a Slack bot that counts reactions and gives rewards to people that get enough/most of them. Need them to be non-anonymous for that. That said, I do think it'd probably also be good to have anonymous up/down votes or whatever (or agree/disagree, etc).

flawr

@DJMcMayhem I just had to look up what it was about, I forget so quickly:)

DJMcMayhem

Yeah, it says you read it a year ago so I'm not surprised

I've sorta been on a mission to read every book by that same author.

Anonymous

16:03

@El'endiaStarman Nope, we hadn't gotten to the point where we thought a custom chat system was worth it

Doorknob

very off topic, but I'm teaching for a program at my college where high schoolers come to take classes on literally anything - does anyone have any suggestions for programming-related things that are cool but also accessible to a significant portion of high schoolers?

(or math-related things)

John Dvorak

Academia-level cryptography?

DJMcMayhem

@Doorknob If you use a simple enough library, I'm sure some game dev would appeal to lots of them. Game dev is a great way to get introduced to programming since making shapes move on a screen is way more exciting than printing text

John Dvorak

AKA modular exponentiation, and if you're really nice I'll even tell you why it works?

DJMcMayhem

(e.g. pygame, Game maker studio, maybe qml)

@JohnDvorak Or that. That's a good one too :P

@DJMcMayhem That sounds really weird to say. But I've been playing around with qml for game design, and it's been working decently well so far.

And it's simple enough as a language that I've been teaching it to my wife who has almost no programming experience

ngn

16:26

@Doorknob rule30 is simple and cool (i admit i did look at the starboard)

J. Sallé

@DJMcMayhem that's really cool.

I managed to teach a friend from college, who studies sociology, how to do some simple stuff in APL the other day

H.PWiz

@Doorknob I think fractal stuff is always good

Adám

@J.Sallé Some of the first stuff my father did in APL was model human behaviour.

DJMcMayhem

@H.PWiz Oh yeah, graphical-output could also be really good

J. Sallé

@Adám really? How awesome. I taught her only the very basics because I also had to introduce her to stuff like vectors, matrixes and such

Adám

16:36

@Doorknob Tying into fractals, Fibonacci numbers are fun.

Doorknob

16:49

those are all neat ideas, thanks!

New Meta Posts

17:07

0

Q: When can challenges be reused? If never, then why can't I answer?

According to this meta post we can never recreate old challenges. Of course not, its a duplicate. Makes sense to me. No problems. Except this challenge can no longer be answered with a language newer than the challenge, even though the requirement that "languages be newer than the challenge" is ...

discussion

El'endia Starman

17:22

CMC: given a list L and an integer n where 0 <= n < 2**len(L), return a list that has the first element if n & 1, the second element if n & 2, the third element if n & 4, and so on.

Adám

@El'endiaStarman &?

El'endia Starman

Bitwise and.

This actually just now came up in a test I'm writing for work, in Python.

Adám

@El'endiaStarman I don't get it. Wouldn't n & m give a non-Boolean?

DJMcMayhem

@Adám It'll give either 0 or 1, which could be treated as a boolean

El'endia Starman

Since n=3, I could just write 4-7 lines of code and call it, but I wondered if I could do it in one line.

DJMcMayhem

17:24

(If m is a power of 2)

Adám

@DJMcMayhem Ah, I see now, 4, not 3. OK.

@El'endiaStarman In other words, filter L by the bits of n

El'endia Starman

@DJMcMayhem Technically, it's "0 or not-0" since e.g. 7 & 4 = 4.

@Adám Yup.

DJMcMayhem

Oh yeah, of course

Adám

@El'endiaStarman Is there an upper bound on the len(L)?

El'endia Starman

@Adám If we're going for purity, no. Practically, whatever. Just...not as low as 2 or 3.

Adám

17:28

@El'endiaStarman APL (Dyalog Unicode), 13 bytes {⍵/⍨⍺⊤⍨2⍴⍨≢⍵}

J. Sallé

@Adám when you said that, I immediatelly thought of /. Good to see I wasn't wrong

ngn

@El'endiaStarman there must be an x86 simd instruction for that

Adám

@ngn compress

ngn

@Adám is marshall behind your back? :)

Adám

@ngn No, he's downstairs, but I actually knew this one.

ngn

17:31

just joking

DJMcMayhem

@El'endiaStarman Jelly, 4 bytes: BUTṃ

ngn

@Adám the term is actually "gather-scatter", i guess "gather" in this case

Doorknob

@El'endiaStarman in python, the shortest i can think of is lambda l,n:[a for a,b in zip(l,bin(n)[::-1])if'0'<b]

which is 52

flawr

@Doorknob how old ar high-schoolers?

DJMcMayhem

Same algorithm, shorter in MATL: BP)

Doorknob

17:36

@flawr 14-18, generally

Adám

@El'endiaStarman APL (Dyalog Extended), 10 bytes ⊣⌿⍨-⍤≢⍛↑∘⊤ with the disclaimer that I don't understand how that can work ¯\_(⍨)_/¯

El'endia Starman

@Doorknob Is that Python 2?

Doorknob

it should work in both

El'endia Starman

First attempt in Python 3 is 68 bytes, but it feels like I could definitely do better.

Doorknob

oh wait, this breaks when there aren't as many binary digits as elements

DJMcMayhem

17:39

@Doorknob Doesn't work because of the 'b' in bin

53 if you change it to '1'==b

flawr

@Doorknob hm that is quite a range

Doorknob

@DJMcMayhem or change [::-1] to [:1:-1], either works

flawr

@Doorknob how much time do they have?

Doorknob

each class is either 0:50, 1:50, or 2:50

DJMcMayhem

@Doorknob lambda l,n:[b for a,b in enumerate(l)if 2**a&n] for 47

El'endia Starman

17:42

@DJMcMayhem Oh man, this is elegant.

DJMcMayhem

Or lambda l,n:[b for b in l if 2**l.index(b)&n] for 44 if elements will be unique

Doorknob

@DJMcMayhem ah, nice

caird coinheringaahing

@Doorknob Is that 50 minutes, or 30? 1hr 50min seems like an odd length for a class

Doorknob

50, we run on modified time where all events begin and end with a 5 minute offset :)

(that way there's time between things to get to other things)

DJMcMayhem

That makes sense.

El'endia Starman

17:44

Bah, Doorknob beat me to that answer. :P

caird coinheringaahing

@Doorknob Ah, right. Our school works by setting 3 minutes aside after each hour long class for movement

J. Sallé

@DJMcMayhem I refuse to believe this is Jelly. I can read all the characters in this program.

DJMcMayhem

@J.Sallé BUT- mmmm....

Doorknob

you gotta pronounce the underdot

Adám

CMC: Given a list, return an all-zero list of same length, but with the positions of first occurrences of each unique element set to the count of that element. E.g. [3,1,4,1,5,9,2,6,5,3,5,8,9,7,9] → [2,2,1,0,3,3,1,1,0,0,0,1,0,1,0]

DJMcMayhem

17:51

@Adám Python 3, 63 bytes: lambda l:[[0,l.count(b)][l.index(b)==a]for a,b in enumerate(l)]

Doorknob

@Adám 51 in ruby: ->a{i=-1;a.map{|x|a.index(x)==(i+=1)?a.count(x):0}}

dzaima

@Adám Dyalog APL Extended, horrible 16 bytes

Adám

@dzaima Oh my! You're forgetting a primitive that's staring at you.

dzaima

@Adám ಠ_ಠ yeah. I did originally use dyadic ⍧ but somehow i just couldn't give it a non-∪ ⍺

John Dvorak

18:16

Ruby (41): ->a{r={};a.map{|x|r[x]?0:r[x]=a.count(x)}}

Honestly I'm quite surprised I didn't need extra spaces

Correction: 42 bytes

AdmBorkBork

18:30

@Adám PowerShell, 54 bytes: param($l)$a=@{};$l|%{(0,($l-eq$_).count)[!($a[$_]++)]}

Unrelated String

18:53

Jelly, 6 bytes

...5 bytes

Adám

@UnrelatedString Whoa, APL beats Jelly‽ You must have missed something…

Pavel

@Adám I just got an email about Dyalog 17.1 coming out, are there any golf-relevant things that would be good to know about?

37 pages of patchnotes...

Adám

@Pavel The only core language feature would be that dyadic ⍸ now allows duplicates. But hey, you've got Chromium under Linux now :-)

Pavel

Linux support is nice

Adám

@Pavel Try ]plot ×⍨⍳99

Pavel

19:04

@Adám Can I do that online somewhere? I'm on my phone.

And it doesn't seem TIO is updated yet

Adám

@Pavel TIO is updated, but Dennis have not given us graphical output yet…

Pavel

Ah, I should have guessed from ]plot

And the fact that there wasn't even a ⍸ in there

Which is what I immediately assumed was being demonstrated

Adám

@Pavel 2 3 3 4 ⍸ 3 1 4 1 5

@Pavel I'll keep pushing for Dyalog for Android… Feel free to nag support@ too.

Pavel

@Adám Does Dyalog for Linux support ARM? Because if it does, you could just run the linux version on Android

Adám

@Pavel We have Dyalog on Pi. The problem isn't the interpreter itself — it already runs on Android — we need an IDE that is suited for a small touchscreen.

Pavel

19:18

I think there might be more interest and value in porting the IDE that already exists to Linux rather than designing a brand new one for Android

Adám

@Pavel That can already run, since the interpreter can serve that IDE to a local port, so you can direct any Android browser to it.

@Pavel But don't you think it'll be a bit crammed? RIDE is intended for use with keyboard and mouse.

Pavel

IMO, all that's really necessary is a terminal emulator and an a keyboard with APL symbols and everything else is wasting screen space

Adám

@Pavel I'm with you. That's what I've been saying should be the first Dyalog APL for Android: a powerful calculator app. But then we have to deal with (multi-line) function editing, and what happens if a function hits an error etc.

Pavel

Terminal emulators these days happen to be more complex than a teletype and do in fact allow you to move the cursor up a line

Adám

@Pavel APL Keyboard is a solved problem. APL font too…

Pavel

19:27

All that's left is to install the Termux app and launch the repl

Adám

@Pavel Right, and Dyalog runs quite fine in a terminal emulator on non-Windows.

Pavel

@Adám Is there just a tarball distribution of APL for Linux? I'm the site and I see rpm and deb packages but my system supports neither of those.

Adám

@Pavel Can you write support@ asking for that?

Pavel

I will do that

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