The APL Orchard

7:49 AM

@justin2004 ^ although that will fail if there's no space after the leading digits. {⍵[⍋{⍎'0',⍵/⍨∧\⍵∊⎕D}¨⍵]} is concise and handles that but {⍵[⍋{⊃2⊃⎕VFI'0',⍵/⍨∧\⍵∊⎕D}¨⍵]} is faster. See also github.com/abrudz/Sort

4 hours later…

12:18 PM

@user23207160 Hi robert lonigro, if you want to participate here, please email access@apl.chat

@EssieRivers Where? Surely, it is possible to either call them dyadically instead, or to look at their source and choose how to call them?

1:00 PM

Welcome to APL Quest, 2023-3! Today's quest is Caesar Salad:

> In a Caesar cipher, each letter in the plaintext is replaced by a letter some fixed number of positions away in the alphabet, effectively "shifting" the alphabet.
Write a function that:
• takes a single integer left argument representing the size of the shift
• takes a character vector right argument representing the plaintext message
• returns a result with the same shape as the right argument representing the encrypted message

> Notes:

> • Use ' ',⎕A as the alphabet

> • You can assume that the plaintext message will contain only characters found in the alphabet.

{(⍺⌽a)[⍵⍳⍨a←' ',⎕a]}

That's nice.

I did not make a solution but can share my entry from last year. Not very advanced

{ r←⍺⌽a←' ',⎕A ⋄ r[a⍸⍵]}

Yeah, that's the same, since ⍳ and ⍸ are equivalent for found values.

I wonder if it is possible to write a tacit version that is invertible.

you mean something with under?

1:06 PM

No, just something where you can write ⍣¯1 to undo the encryption.

Btw, you don't have to rotate the alphabet. Another option is using | (with ⎕IO←0 or adjustment — why isn't | sensitive to ⎕IO‽)

I thought about converting the alphabet to numbers, adding the offset and than converting back. Which under can be used for?

Ah, that should work with Under.

@Adám something like {a[(≢a)|⍺+⍵⍳⍨a←' ',⎕a]}?

Yes.

But ≢a is always 27.

this seems to pass the tests even without io 0

@Adám sure, but this is one of the cases where magic numbers make the code less clear

nevermind, it only passes the tests some of the time

1:13 PM

Hm, we should fix that. The tests are semi-random.

of topic, but what should I do with this error message? Cant startup Dyalog:
A fatal error has occurred. Dyalog APL cannot continue.

In workspace (process ID:12464)

Syserror: 999 code: 0

Interpreter BuildID: 0x4afd1d1b
Interpreter Created: Oct 28 2022 at 05:17:18
Interpreter Version 120.22.46169.0 / 64 / Unicode

Serial Number : unavailable

If you choose to generate an aplcore, it will be saved as: "C:\windows\system32\aplcore".
It may be possible to retrieve objects from this file using:

No need to answer it now

@Richard Got it: {(27|⍺∘+)_U_((' ',⎕A)∘⍳)⍵}

Ah yes :)

I had a not succesfull atempt

how nice

any other approaches to this problem?

@Richard If it happens every time you start Dyalog, re-install. But please zip and email the C:\windows\system32\aplcore file to support@dyalog.com

1:17 PM

@RubenVerg Not other approaches. It can be generalised to any character array and any alphabet, but the general approach would be the same…

… so I think we're about done.

can you spice up the next one?

btw I didn't use <. So probably many possibilties

@Richard Sure, handle a fourth element which can be something like 'alpha' or 'beta', rc etc.

ok!

Fine, see you next week for 2023-4: Like a Version!