The Nineteenth Byte

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Mr. Xcoder

00:43

@Jono2906 The legacy version is written in Python, the new one is written in Elixir. The Python code was kind of messy and implementing new features couldn't really be done systematically. And the Elixir version adds some crucial features like infinite list support and related functions, and adds a whole bunch of new commands

Jono 2906

@Mr.Xcoder aha

Mr. Xcoder

Just to be clear, the Python code wasn't impossible to work with. Rather, the main reason for the shift is making use of Elixir's special features (even though the code itself is indeed cleaner anyway)

Jo King

01:12

@mınxomaτ That's a lot of porn

4 hours later…

New Main Posts

04:47

Q: Decomposition of a matrix in \$ SL_2(\mathbb{Z}) \$

Background The special linear group \$ SL_2(\mathbb{Z}) \$ is a multiplicative group of \$ 2 \times 2 \$ matrices whose elements are integers and determinant is 1. It is known that every member of \$ SL_2(\mathbb{Z}) \$ is a product of some sequence of the following two matrices \$ S \$ and \$ ...

3 hours later…

Fatalize

08:13

@flawr Robert Cartaino too, apparently

2 hours later…

Anush

10:28

hello!

4 hours later…

Anush

14:47

CMC "grep" a text file so that it shows only lines that have "xyz" in the subsequent line

a'_'

I finally got into an active chatroom! (Previous attempts have resulted in chatrooms with nobody inside.)

Anush

@a'_' hello!

Veskah

a'_'

hello!

Adám

@Anush Can we take the file as list of strings or must it be a file name or can we use a file handle?

Anush

14:54

@Adám because it's just for fun, I would prefer a file name or standard in

Adám

@Anush What to do if first line has "xyz"?

a'_'

@Anush GolfScript, 16 bytes

I'm not sure whether this fully works though, I haven't fully tested it yet.

Anush

@Adám you are not outputting anything for that instance

dzaima

@a'_' does weird stuff with "xyz" being surrounded

a'_'

@dzaima I guess it can be fixed with a set xor-ing.

Adám

14:59

@Anush APL, 27: f⌿⍨0,⍨1↓∨/'xyz'⍷↑f←⊃⎕NGET⍞1

Anush

@Adám the input has one line?

I don't understand what I am looking at

Adám

@Anush file name.

a'_'

@Anush (Repost) GolfScript, 44 bytes

Anush

interesting

grep -2 xyz foo.txt|grep -v xyz almost does it

a'_'

@Anush (Repost-repost) GolfScript, 39 bytes

Anush

15:13

27 vs 39....

a'_'

I use GolfScript just for fun, not for bytecount. (Also I'm just a GolfScript beginner so there are a lot of tricks that I don't know yet...)

Anush

I think it's all for fun!

I am considering a possibly controversial new challenge...codegolf.stackexchange.com/questions/197524/… but with 3 changed to 4. I think it will be really hard to solve it as easily

ngn

@Anush k: {a@&1_"xyz"~/:a:0:x}

Anush

@ngn TIO?

ngn

how do i make a file there?

a'_'

15:26

@ngn I guess STDIN is stored as a separate file on TIO.

Anush

@ngn did you see that someone may have cracked Kaseorg's mysterious dynamic programming algorithm?

ngn

@Anush oh cool

@Anush tio

@a'_' turns out we can write in /tmp

Anush

cool

a'_'

@Anush GolfScript, 30 bytes

Anush

nice!

a'_'

15:42

@Anush GolfScript, 29. Plz don't mind when I post so many times...

ngn

@Anush have "xyz" in the subsequent line - as a substring or exact match?

Christian Sievers

@Anush [tio.run/##SyzP/v9fv6KySl9NzS/IzrC6oCgzr0Qhv5arOt9WxaD2/… awk, 27 bytes]

Kritixi Lithos

@Anush sed -n, 18b, :;N;/\n.*xyz/P;D;b

i've lost touch, sed -n at 14b, N;/\n.*xyz/P;D

N adds newline + next line to pattern space, if the pattern space matches /\n.*xyz/, P prints the first line. Finally, D removes the first line until (including) the first newline, and runs the program from the start on what is remaining

Anush

16:24

very glad to see awk and sed solutions!

the sed one is surprising!

Neil

I was expecting /xyz/{x;p;x};h but I don't know whether it works

Kritixi Lithos

much neater, but unfortunately fails for when there is a match on the first line

@Neil in case you weren't aware, i posted an infinite bounty for outgolfing my sed solution to fizz buzz

Neil

hey I'm no sed expert

Kritixi Lithos

16:39

:( but you know retina it should be easy

doing non-unary arithmetic in sed is much more fun, because sed is inferior to retina

Neil

ah, so for your sed script, you're basically already on line 2 when you start matching

Kritixi Lithos

also there are a lot of approaches in sed for fizzbuzz, as can be seen in anagol's sed leaderboard for sed golf.shinh.org/p.rb?FizzBuzz#sed, none of the top solutions are at the same bytecount

@Neil s/basically//, = after encountering N for the first time gives 2

Anush

17:06

how would you draw a random curved line in python?

or julia... :)

1 hour later…

New Sandboxed Posts

18:13

A: Sandbox for Proposed Challenges

How low can you go? Time to play so ascii-art limbo! Here's the bar: |--| | | | | Can you fit under it? Goal Write a program or function that takes an ascii string representing a some shape, and a positive integer representing a bar height. Output the shape from the input after it has a...

4 hours later…

New Sandboxed Posts

22:40

A: Sandbox for Proposed Challenges

Lattice walk home You start at some integer coordinates \$(x,y)\$ on the integer lattice and you want to walk back home to \$(0,0)\$. You may take one step North, South, East, or West. Your goal is to repeatedly do this and end up home. Given \$(x,y)\$, write code that outputs one of the four d...