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11:00 AM

Does @ have an obvious solution to select a non-major axis? That is, a column.

⎕←i←1⋄v←4 3⍴'abcdefghijkl'⋄⌽@{(⍴v)⍴i=⍳1↑⌽⍴⍵}⊢v

@Ven
1

Ven

I'd like something like this instead, with 0 being a "?" value, kinda like X[;Y] indexing:

⎕←v←4 3⍴'abcdefghijkl'⋄⌽@(⊂0 i)⊢v

Dyalog APL

@Ven
abc
def
ghi
jkl
VALUE ERROR

Ven

...I'm fairly sure I already asked about this last year when I first learned about @, but I can't find it anymore (and searching for "@" or "at" in the transcript simply doesn't work for good reasons)

Adám

@Ven Either do it "under" transpose ⍉⍺⍺@⍵⍵⍉ (or f@⍢⍉ in Extended) or, depending on what you're doing, use ⍺⍺@⍵⍵⍤1.

Ven

11:09 AM

I don’t think I get it

Adám

@Ven Here:

⎕←10+@2⊢3 3⍴⍳9

Dyalog APL

Adám

⎕←⍉10+@2⍉3 3⍴⍳9

Dyalog APL

Ven

Duh. Obviously.

I still don’t have the brain for it :D. thanks

Adám

11:14 AM

@Ven For "Rotate a column", right? I've got a 16-byte solution.

10 bytes in Extended.

Ven

11:33 AM

Yes

The input format is a bit annoying however

Adám

@Ven It isn't really the input format's fault, as much as spaces and even ⎕UCS 0 must be treated as normal characters, so nothing of the relevant datatype can be used as fill. In my answer, I use numbers as fill for character data.

@Ven Ah, there is a solution:

> • The number of possible values of the data type of the elements must be at least 20 if your code length depends on it, otherwise at least 2. This could be a subset of the characters or other values supported in the native type.
• Spaces and any kind of null values are just normal values (if you allow them in the input).

1 hour later…

Ven

12:49 PM

Assigning to ⎕ doesn't work in TIO, so I just use globals

the Extended unary ≠ trick is nice :)

Adám

@Ven Assigning to ⎕… Wat?

Ven

Well, ⎕←.

Adám

@Ven What do you mean by ⎕← not working?

Ven