Please excuse my bad form in replying to my own message. I see now there is
a subtle difference in the two expressions (namely, a down-arrow in the
left edge of the outermost box in the second form below):
(w w w w w)
> ┌→───────────────────────────────────────────┐
> │┌→─────┐ ┌→─────┐ ┌→─────┐ ┌→─────┐ ┌→─────┐│
> ││listen│ │listen│ │listen│ │listen│ │listen││
> │└──────┘ └──────┘ └──────┘ └──────┘ └──────┘│
> └∊───────────────────────────────────────────┘
> ⍴(w w w w w)
> ┌→┐
> │5│
> └─┘
> (∊1 (⍴cl))⍴⊂w
> ┌→───────────────────────────────────────────┐
> ↓┌→─────┐ ┌→─────┐ ┌→─────┐ ┌→─────┐ ┌→─────┐│
> ││listen│ │listen│ │listen│ │listen│ │listen││
> │└──────┘ └──────┘ └──────┘ └──────┘ └──────┘│
> └∊───────────────────────────────────────────┘
> ⍴(∊1 (⍴cl))⍴⊂w
> ┌→──┐
> │1 5│
> └───┘
> ⍴((∊1 (⍴cl))⍴⊂w)[1;] ⍝ Very ugly, but this seems to coerce to
> match the above ⍴(w w w w w)
> ┌→┐
> │5│
> └─┘
I suppose this is the reason one form works as an argument to my function,
where the other does not.
I still seek to understand why APL does not apply scalar extension on the
left arg though, to avoid needing either of these manual expansions to
match a single left arg with the list of right args.
-Russ
On Thu, 29 Jul 2021 at 22:48, Russtopia <rma...@gmail.com> wrote:
> Hello, I am trying an exercise that finds anagrams of a word from a list
> of candidate words.
>
> I am having issues with scalar extension of the left arg, which I thought
> should automatically repeat the scalar left arg to match each item in the
> right vector arg. It seems to work only if I do the expansion manually
> (that is, repeat the left arg explicitly rather than let APL do it).
>
> (If formatting below is not readable, please convert it to a fixed-with
> font)
>
> w
>> ┌→─────┐
>> │listen│
>> └──────┘
>> cl
>> ┌→────────────────────────────────────────────┐
>> │┌→──────┐ ┌→─────┐ ┌→─────┐ ┌→─────┐ ┌→─────┐│
>> ││enlists│ │google│ │inlets│ │banana│ │tinsel││
>> │└───────┘ └──────┘ └──────┘ └──────┘ └──────┘│
>> └∊────────────────────────────────────────────┘
>> ⎕cr 'is_anagram_of'
>> ┌→──────────────────────────────┐
>> ↓r ← word is_anagram_of other │
>> │r ← word[⍋word] ≡ other[⍋other]│
>> └───────────────────────────────┘
>> w is_anagram_of cl
>> 0
>> w is_anagram_of ¨ cl ⍝ <-- Should this not implicitly expand
>> left arg?
>> DOMAIN ERROR
>> is_anagram_of[1] r←word[⍋word]≡other[⍋other]
>> ^ ^
>> w w w w w is_anagram_of cl ⍝ <-- this works, w w w w w matches
>> ⍴cl
>> 0
>> w w w w w is_anagram_of ¨ cl
>> ┌→────────┐
>> │0 0 1 0 1│
>> └─────────┘
>> (w w w w w is_anagram_of ¨ cl)/cl
>> ┌→────────────────┐
>> │┌→─────┐ ┌→─────┐│
>> ││inlets│ │tinsel││
>> │└──────┘ └──────┘│
>> └∊────────────────┘
>> (∊1 (⍴cl))⍴⊂w
>> ┌→───────────────────────────────────────────┐
>> ↓┌→─────┐ ┌→─────┐ ┌→─────┐ ┌→─────┐ ┌→─────┐│
>> ││listen│ │listen│ │listen│ │listen│ │listen││
>> │└──────┘ └──────┘ └──────┘ └──────┘ └──────┘│
>> └∊───────────────────────────────────────────┘
>> w w w w w
>> ┌→───────────────────────────────────────────┐
>> │┌→─────┐ ┌→─────┐ ┌→─────┐ ┌→─────┐ ┌→─────┐│
>> ││listen│ │listen│ │listen│ │listen│ │listen││
>> │└──────┘ └──────┘ └──────┘ └──────┘ └──────┘│
>> └∊───────────────────────────────────────────┘
>> ((∊1 (⍴cl))⍴⊂w) is_anagram_of ¨ cl ⍝ <-- ?? Why does this not
>> work as (w w w w w)?
>> RANK ERROR
>> ((∈1(⍴cl))⍴⊂w)is_anagram_of¨cl
>> ^ ^
>
>
> Advice appreciated,
> Thank you,
> -Russ
>
