The APL Orchard

Brian BED

00:13

when writing examples, should i assume the veiwer is using ⎕IO 0 or 1? currently i'm stating "with ⎕io 0:" at the top, but i could make it 1

Adám

The default is 1, but it is good practice to specify.

Brian BED

00:53

ok done with my first page! I did mostly examples for the page "assignment", and it was pretty fun. not much, but it's honest work :D
https://aplwiki.com/wiki/Assignment

Adám

01:30

@BrianBED Thanks. I've polished it a bit. Still needs treatment of selective assignment, function assignment, examples of global vs local assignments in tradfns and dfns, including discussion of the issues in dfns, more external links, etc. but it is indeed a good start.

Brian BED

01:46

¯\_(ツ)_/¯ I try

ah i like how pretty you made it look :D

Razetime

02:52

has anyone here made an attempt at using CoSy?

@rak1507 wait till you see CoSy docs

PyGamer0

06:14

in The Nineteenth Byte, 6 mins ago, by PyGamer0

using @dzaima 's paste, i made a tryAPL frontend

Adám

08:35

@RGS @xpqz Did you ever look into serving a non-default font for the code in Jupyter Books? People are complaining about rendering issues with ≢ that would be solved if you served a proper font.

xpqz

I’ve tried, but have been unable to work out how to do it, as I’m unable to test.

Adám

I thought you could inject custom CSS.

Adám

08:51

@xpqz Looks like this would do it.

@xpqz I think the flow will be easier to understand if the "We can model ⊥ as:" has reversed left arguments and does ⌽×\⌽

Maybe even revise everything from the beginning to do ⌽×\⌽ throughout, i.e. ⌽×\⌽(2⍴10),1 etc.

And again, ×\⌽1 1 1 is wrong. It should be ⌽×\⌽1 1 1

And harmonise ⌽×\1,⌽1↓0 0 0 to ⌽×\⌽1↓0 0 0,1

@xpqz MathJax mess-up after "Compare this to making cash change: there’s nothing larger than a"

xpqz

09:06

@Adám Sure. That’s the first attempt I had. But no css I add through that route seems to do it.

Adám

@xpqz Could you observe that the CSS was injected?

Hm, now I look at ⊤ maybe the formulation ⌽×\⌽1,⍨1↓ is best, as it puts all transformation on the left, keeping the base on the right?

PyGamer0

how do i join two vectors column wise, for example:
1 2 3 <command> 4 5 6
---
1 2 3
4 5 6

xpqz

@Adám Several folk around the web seem to confirm it’s hard or impractical. My css skills aren’t sufficient, I fear.

Adám

@PyGamer0 ↑(1 2 3)(4 5 6) or ⍉1 2 3,⍪4 5 6 or 1 2 3,[0.5]4 5 6 assuming ⎕IO←1

PyGamer0

ok thanks

Adám

09:10

@xpqz If you can get any CSS injected, then we can do it. I can help with the CSS.

PyGamer0

@PyGamer0 i came up with (assuming lengths of ⍵ and ⍺ are same): {2(≢⍵)⍴⍺,⍵}

Adám

@PyGamer0 At that point, {↑⍺⍵} or ↑⍤,⍥⊂ is easier.

PyGamer0

oh

Adám

I'm lobbying for ⍪⍥< to do this.

xpqz

@Adám you can see what I tried here: github.com/xpqz/learnapl/blob/main/contents/_static/custom.css

Adám

09:14

Is the book built with that?

PyGamer0

uh so how do i do a 2×2 sliding window over a matrix?

RGS

@Adám I started trying, haven't given up yet.

PyGamer0

2 3 4
4 5 6
-------
2 3 | 3 4
4 5 | 5 6

Adám

@PyGamer0 ⋄ {⊂⍵}⌺2 2 ⊢ 2 3⍴2 3 4 4 5 6

TryAPL

@Adám
┌───┬───┐
│2 3│3 4│
│4 5│5 6│
└───┴───┘

PyGamer0

09:17

thanks

Adám

@RGS @xpqz Adding tt,code,kbd,samp,pre,.output.text_html span{font-family:codefont!important} to custom.css seems to do the trick.

@xpqz Under complex numbers, u v←4j6 1j2 should say (u v)←4j6 1j2

RGS

09:42

@Adám That seems to assume codefont refers to something else..?

Adám

@RGS Yeah, look at learnapl's custom.css:

@font-face {
  font-family: 'codefont';
  src: local('DejaVu Sans Mono'),
       local('APL385 Unicode'),
       local('SImPL'),
       url(aplwiki.com/images/7/75/DejaVuSansMono.ttf) format('truetype');
}

RGS

That's what I thought of doing, yeah :D

Well, for MDAPL, should I not use APL385 by default?

I.e. reorder the locals and add a url to APL385?

Adám

Sure.

RGS

Do you know if APL Wiki also hosts the APL385 font?

PyGamer0

⋄1 2 3{r←{⊂-/×⌿⍉⍵}⌺2 2⊢↑(4⍴1⌽⊢)¨⍺⍵⋄¯1↓r÷⊃⌽r}4 5 6

TryAPL

09:44

@PyGamer0 Response looks like a 0-by-0 matrix.

PyGamer0

why

Adám

@RGS (CC: @xpqz) I would host the font file in the same repo; otherwise it constitutes XSS.

RGS

Right.

Adám

@PyGamer0 You drop one row from the matrix 1 3⍴1.333333333 1.166666667 1

PyGamer0

hm

⋄1 2 3{r←{⊂-/×⌿⍉⍵}⌺2 2⊢↑(4⍴1⌽⊢)¨⍺⍵⋄¯1↓3⍴r÷⊃⌽r}4 5 6

TryAPL

09:46

@PyGamer0 1.333333333 1.166666667

PyGamer0

oh

Adám

You can use , instead of 3⍴

Or alternatively, use 2⍴ instead of ¯1↓3⍴

PyGamer0

oh yeah

Adám

⋄ 1 2 3{2(↑÷↓),{⊂-/×⌿⍉⍵}⌺2 2⊢↑(4⍴1⌽⊢)¨⍺ ⍵}4 5 6

TryAPL

@Adám 1.333333333 1.166666667

Adám

09:50

@PyGamer0 Btw, {⊂-/×⌿⍉⍵} is just {-/×/⍵} no?

PyGamer0

@Adám does the drop the last one and divides the rest by that and takes the first 2 of that?

@Adám yes

Adám

@PyGamer0 No, it divides the 2-take by the 2-drop.

PyGamer0

so it drops the first 2

ah it makes sense now

Adám

Since X(f g h)Y is (X f Y)g(X h Y)

@PyGamer0 Which ⎕IO do you use?

PyGamer0

0

Adám

09:54

Then 2(↑÷⌷), or 2(↑÷⊃), would actually be better.

… because it doesn't rely on APL's quirky treatment of 1-element arrays as scalars.

PyGamer0

how do i get both diagonals

example:
1 2
3 4
---
1 4
2 3

Adám

@PyGamer0 The ⊢ in ⊢↑(4⍴1⌽⊢)¨⍺ ⍵ is unnecessary. The rest can be written as 4⍴⍤1⊢1⌽↑⍺⍵ or m,⊣/m←1⌽↑⍺⍵

@PyGamer0 Always of a 2-by-2 matrix?

PyGamer0

yes

Adám

⋄ 0 1⊖⍉2 2⍴⍳4

TryAPL

@Adám
1 4
2 3

PyGamer0

10:01

oh

finally i made it

⍝ Homework solver X
⍝ Solves linear equations in 2 variables
solve ← {2(↑÷⊃),{-/×/0 1⊖⍉⍵}⌺2 2⊢4⍴⍤1⊢1⌽↑⍺⍵}

Adám

⌹

PyGamer0

@Adám ?

Adám

Can you give an example of a homework problem that your solve solves?

PyGamer0

hmm wrong

TryAPL

@PyGamer0 0.4285714286 1

Adám

10:06

What is the homework task here?

PyGamer0

@Adám wait

Adám

Note that
2x+3y=4
4x+5y=6
can be solved with

⋄ 4 6⌹2 2⍴2 3 4 5

TryAPL

@Adám ¯1 2

Adám

meaning x=-1, y=2

PyGamer0

ooh

@Adám tinyurl.com/4tuw26ca

Adám

10:11

@PyGamer0 solve←{(-⊢/¨⍺⍵)⌹↑2↑¨⍺⍵}

Don't get me wrong: This doesn't diminish your accomplishment — well done!

xpqz

10:33

@Adám ok, I’ll try that this afternoon hopefully. Many thanks

PyGamer0

so ⌹ dyadic is matrix divide?

Adám

Yes.

PyGamer0

so ⌹⍣¯1 will be matrix multiplication ?

Adám

Well, there's +.× for that.

Dyadic ⌹ is +.×⍣¯1⍨

PyGamer0

⋄5(⊢⍣¯1)3

TryAPL

10:44

@PyGamer0 3

Adám

⊢⍣¯1 is ⊢

PyGamer0

why not ⊣?

Adám

That's not what ⍣¯1 means. f⍣¯1⊢Y means "find my a Z such that f Z gives Y

X f⍣¯1⊢Y is just X∘f⍣¯1⊢Y

PyGamer0

oh

Adám

So 5(⊢⍣¯1)3 means "find me a Z such that 5∘⊢Z gives 3, which only holds for Z←3

@Ashy Hi there. Interested in APL?

Ashy

10:57

hi @Adám mostly interested in J but APL too yeah

Adám

Nice. Welcome to the Orchard then. How much experience do you have with J (and APL)?

Ashy

I've been playing around with j for the past year or so and a small amount of APL from some of the papers and videos

Adám

OK, cool. People here are always happy to help if there's anything.

Ashy

cool, I might ask the odd golfing question or two as I work through the code.golf problems :)

Adám

Have you seen this?

36

Q: Tips for golfing in J

GolfScript gets its own way far too often and I feel that a repository of handy hints for golfing in J might help in the fight against the evil empire. What tips do you have for making this already terse language shorter? For those wanting to learn J, the obvious place to begin is the jsoftware ...

Ashy

11:03

yeah i've read through that a little, seems like a really good reference

oh i've been listening to the array cast since it started too, great stuff from you and the crew

it's by far my favourite podcast

Brian BED

@rak1507 just to make sure. do you need the middle parenthesis? i removed them just to test and it still seems to work, tho i wanna make sure there aren't edgecases

wait sorry i'm stupid. it returned error, i just didn't notice :|

Adám

@BrianBED Yeah, ⎕NEW needs an argument consisting of (one or) two elements. The first has to be ⊂class where class can be a ref or a charvec. The second (if present) has to be a (scalar or) vector of name-value pairs.

RGS

12:45

@xpqz the font saga has come to a close. See my custom.css file for the CSS I'm using to style the book with APL385 (thanks Adám!). To check it is working, you can visit, for example, this link.

In order to serve the font(s) from the repo, all you have to do is make sure the .ttf files are in the _static folder. E.g., my APL385.ttf file can be seen here.

Adám

@RGS You can use local before serving.

xpqz

@RGS Ha, I just deployed the cultivations book with something eerily similar :)

I'll pinch the APL385 font.

RGS

@Adám I have no idea what that means 🙃

@xpqz You can use whatever font you want :P I'm just saying I used the APL385.

Adám

@RGS local('APL385 Unicode'), first, so the client can use a local copy if it exists, rather than making another request to the server.

xpqz

It's the nicest one.

RGS

12:48

@Adám Oh, I get it.

xpqz

@RGS Now, for the phone-number-rendering saga.....

RGS

@xpqz I'm not done with that :)

(Sadly,) I have been prioritising other things.

Adám

13:02

@RGS How is this for a MDAPL logo (for the Jupyter Book, left side, above the title)?

In context:

rak1507

looks good

Adám

Feels modern/fresh enough, while being a direct derivative of the original cover:

xpqz

13:22

How about using one of the newer glyphs introduced since the original was published, to emphasise the point?

Adám

Actually interesting. The topmost block in the original illustration has ⍤ (or ⍥?) instead of ⍳

I suppose it was replaced last-minute by someone noticing that that wasn't a Dyalog APL glyph.

xpqz

Over, power and selfie :)

All the diaresis favourites

Adám

⍨ and ⍣ are covered in the original MDAPL.

Brian BED

14:22

Ok I made sure to be as formal as possible and asked nicely :D
crossed fingers

xpqz

17:21

@Adám I'm getting different relative performances on the word count approaches from Lesson 30. Within expected tolerances, or did something get optimised?

      cmpx '≢''[^,]+''⎕S 3⊢t' 's(≢≠⊆⊢)t' 's{+/0 1⍷⍺=⍵,⍺}t'⊣ s←',' ⊣ ⎕←≢t←',XY'[/⍨?1e6⍴3]

2001020

┌→─────────────────────────────────────────────────────────────────────────┐
↓  ≢'[^,]+'⎕S 3⊢t  → 1.3E¯1 |   0% ⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕│
│  s(≢≠⊆⊢)t        → 1.4E¯2 | -90% ⎕⎕⎕⎕                                    │
│  s{+/0 1⍷⍺=⍵,⍺}t → 2.8E¯2 | -79% ⎕⎕⎕⎕⎕⎕⎕⎕⎕                               │
└──────────────────────────────────────────────────────────────────────────┘

(or is it my 18.1 beta?)

Kamila Szewczyk

17:44

      'cmpx'⎕cy'dfns'
      cmpx '≢''[^,]+''⎕S 3⊢t' 's(≢≠⊆⊢)t' 's{+/0 1⍷⍺=⍵,⍺}t'⊣ s←',' ⊣ ⎕←≢t←',XY'[/⍨?1e6⍴3]
1999578
  ≢'[^,]+'⎕S 3⊢t  → 5.1E¯2 |   0% ⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕
  s(≢≠⊆⊢)t        → 7.4E¯3 | -86% ⎕⎕⎕⎕⎕⎕
  s{+/0 1⍷⍺=⍵,⍺}t → 1.7E¯2 | -67% ⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕

that's my results and i use the normal release

xpqz

Interesting. The expectation was that the last one would be the faster.

Adám

I think ⍷ was slowed down after a bug was found in 18.0's optimisations.

Kamila Szewczyk

the first one is obviously going to be slow and the third one doesn't seem that much more efficient

i imagine ≠⊆⊢ would be fast because it appears in the code relatively often.

Adám

Why isn't 1⊥2</⊣=,⍨ on the list?

Kamila Szewczyk

seems to be the fastest

xpqz

17:54

@Adám Not got to that bit yet...

Adám

@xpqz I didn't look at the lesson. Glad to discover that my mind didn't change since then.

Fawn Locke

I have a script containing `⊃⊢/2⎕NQ#'GetCommandLineArgs'`

And when I run "mapl -script run.apl ⍳5" from the cli it outputs â³5. What's the issue here (I want ⍳5, obviously)

xpqz

@Adám I think this breaks the flow of the lesson though -- the ⍷ solution was billed as the 'next level up' from ≢≠⊆⊢.

I can reformulate it a smidge.

Fawn Locke

Ah. 'UTF-8' ⎕UCS ⎕UCS ⊃⊢/2⎕NQ#'GetCommandLineArgs' works

Adám

18:13

Btw, Curtis Jones has started speaking about his APL usage at apl.wiki/APL_Campfire

Adám

20:13

APL Campfire ft Curtis Jones

►

Stack Exchange Feeds

20:39

0

Q: Idiomatic graphs in APL

APL is great for array type problems but I'm curious as to how best work with graphs in APL. I'm playing around with leet questions, for example question 662. Maximum Width of Binary Tree, the exercise works with Node objects with a value/left/right pointer style, however the test-case uses a bas...

graph tree apl dyalog

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