The APL Orchard

6:37 AM

CMC: generate a star pattern at point ⍵, given matrix size ⍺.

      10{x y←⍵⋄((x+y)=+/¨a)∨((x-y)=-/¨a)∨(y=⊃∘⌽¨a)∨x=⊃¨a←⍳2/⍺}3 5
0 0 1 0 1 0 1 0 0 0
0 0 0 1 1 1 0 0 0 0
1 1 1 1 1 1 1 1 1 1
0 0 0 1 1 1 0 0 0 0
0 0 1 0 1 0 1 0 0 0
0 1 0 0 1 0 0 1 0 0
1 0 0 0 1 0 0 0 1 0
0 0 0 0 1 0 0 0 0 1
0 0 0 0 1 0 0 0 0 0
0 0 0 0 1 0 0 0 0 0

Wong Jia Hau

@Razetime is so omega must be length of 2?

Razetime

yes, it must be a length 2 vector

Wong Jia Hau

does 3 5 means the coordinate (3,5) in your example?

Razetime

3rd row 5th column

so more like (5,3)

Wong Jia Hau

oh ok I see

the 10 in front means 10x10 matrix right?

Razetime

6:48 AM

yes

dzaima

7:02 AM

@Razetime 21

Razetime

wow

dzaima

@Razetime dzaima/APL, 18; apparently that works

Razetime

7:22 AM

@dzaima so ~ works on ints?

eitherway both of these are epic

reduction from 104-72

dzaima

@Razetime apparently. Not really intentional, at least anymore

Razetime

i see

LdBeth

7:43 AM

{{(=/|⍵)∨0=∧/⍵}¨(⍳⍺ ⍺)-⊂⍵}

oh it's essentially the same

Wong Jia Hau

8:06 AM

⎕←10{m←(∘.{(⍺=1)∨(⍵=1)∨(⍺=⍵)}⍨⍳⍺) ⋄ y x←⍵ ⋄ m←(⊖m),[1]1↓m ⋄ m←(⌽m),1↓[2]m ⋄ o←(⍺÷2)+⍳⍺ ⋄ m[o-y-⍺÷2;o-x-⍺÷2]}3 5

TryAPL

@WongJiaHau
0 0 1 0 1 0 1 0 0 0
0 0 0 1 1 1 0 0 0 0
1 1 1 1 1 1 1 1 1 1
0 0 0 1 1 1 0 0 0 0
0 0 1 0 1 0 1 0 0 0
0 1 0 0 1 0 0 1 0 0
1 0 0 0 1 0 0 0 1 0
0 0 0 0 1 0 0 0 0 1
0 0 0 0 1 0 0 0 0 0
0 0 0 0 1 0 0 0 0 0

Wong Jia Hau

my solution doesn't handle out-of-bound origin yet ⍨

LdBeth

ok a more exotic one {(∘.(0∊,)∨∘.=)⍥(|(⍳⍺)∘-)⌿⍵}

you can write it as (∘.(0∊,)∨∘.=)⍥(|(⍳10)∘-)⌿3 5

I believe without ¨ mine has better performance ;)

well monadic ⍳ with vector argument is another source of "consing"

dzaima

8:22 AM

if you want performance

∘.f is as bad for performance as f¨ is (i.e. okay for primitive functions, bad for composite ones)

@Razetime Dyalog, 19

LdBeth

hmm, that's unexpected. it is true that ∘.f cons a lot for non-primitives

dzaima

∘.f has to execute f separately for each pair of items if it isn't special-cased in the interpreter

LdBeth

and the function promotion gets interesting when nested arrays are involved.

Razetime

@dzaima this is a golfing question but thanks

@WongJiaHau nice.

@WongJiaHau that isn't specified, but it's cool if you can do that

Wong Jia Hau

@Razetime thanks man but I think it's horrible though haha

dzaima

8:33 AM

@Razetime (that was a reply to "mine has better performance" from LdBeth)

Razetime

i see

LdBeth

the trick is use primitive outer product only {((0=∘.×⌿)⊃⍤∨∘.=⌿)|(⊂⍳⍺)-⍵}

folding does have some performance loss

I think good APLers are all good at equational rewriting

Wong Jia Hau

`10{(0=∧/∧-/)¨(⍳⍺ ⍺)-⊂⍵}3 `
22 chars

LdBeth

^ well it is 21 APL chars, 36 bytes.

Junyu Zhan

8:49 AM

Hi @Adám, I want to use your keyboard layout on Windows in order to use the ` prefix. How do I uninstall the IME layout which comes with Dyalog? Didn't see them in the Settings. Maybe need to edit the registry?

rak1507

huh, he's not been seen for 2 days, that's quite a bit

Junyu Zhan

lol~

Anyone else know how to uninstall the Dyalog IME Layout?

Razetime

have you tried running the original installer

LdBeth

launch the dyalog install

dzaima

it should just be on the keyboard layout selection thing. Maybe as a sub-layout of some other layout

Razetime

9:04 AM

windows doesn't show it on my side

i think it can only be removed from the dyalog installer

Junyu Zhan

9:15 AM

@Razetime That works. Thanks!

Razetime

yay the wild guess worked

thanks windows

dzaima

@Razetime I'm fairly sure I've successfully manually removed it back when i was on windows, but that's been a while ago

Junyu Zhan

11:08 AM

In the Windows Dyalog IDE when I type )continue or )save some_name, the editor says "Can't save - file could not be created.". Is this because of access permission? Do I need to run Dyalog as adminstrator?

Wong Jia Hau

`10{(0=∧/∧-/)¨(⍳⍺ ⍺)-⊂⍵}3 5` this is wrong, because I should absolute every value first, the following is correct:
`10{(0=∧/∧-/)¨|(⍳⍺ ⍺)-⊂⍵}3 5`

Razetime

12:14 PM

BAA meeting at 16:00 BST today at zoom.us/j/858532665

password is ×/16 40 612

Master Quiz

12:38 PM

@Adám The third description should be "Hook: apply f between Y and (g Y), that is Y f g Y", not "Hook: apply g between [...]"

Junyu Zhan

Also, even though the input buffer size is set to 40k (default), when I close and re-open Dyalog and enter Ctrl + Shift + Backspace, it says "There's no previous line"

Wong Jia Hau

what operator can I apply to f g such that I get {(f a) g (f w)}?

dzaima

g⍥f

Wong Jia Hau

1:05 PM

@dzaima thanks

Razetime

@Razetime *tomorrow

Elias Mårtenson

2:18 PM

Is monadic A⍥B in Dyalog the same as (AB)?

xpqz

Yes. And monadic A⍤B, too, I think.

Elias Mårtenson

2:54 PM

OK, thanks.

1234

7:53 PM

I think you can NOT run something like that on command> APL myscript.apl where myscript.apl contains apl code

on command line

rak1507

Not yet, 18.1 will be able to though

1234

IDE:
Version: 4.3.3463
Platform: MacIntel
Date: 2020-07-07 10:44:21 +0100
Git commit: 0cd6e9faf39a5d6a5f5caa94d1ff51743d5cdd75
Preferences:{
"colourScheme":"Francisco Goya",
"kbdLocale":"en_US"
}

Interpreter:
Version: 18.0.40684
Platform: Mac-64
Edition: Unicode/64
Date: Jun 19 2021 at 00:08:08

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