Re: [Bug-apl] Help with APL expression

[Ala'a Mohammad]

Hi,
Another two ways, Not as compact or optimized, but generate the same output
1)
G groups, C categories, and S strings

G←(⍴∪C)⍴⊂⍬ ◊ C {G[⍺]←⊂(⊃G[⍺]),⊂⍵}¨S ◊ G

I forgot how to suppress the middle output
or in a function

∇ groups ← categories group items
  groups ← (⍴∪categories)⍴⊂⍬
  categories {groups[⍺]←⊂(⊃groups[⍺]),⊂⍵}¨ items

2)
(1+C[x]) ⊂ S[(⍳⍴C)[x←⍋C]]

Best wishes,

Ala'a

On Wed, Jul 5, 2017 at 2:48 PM, Louis de Forcrand <address@hidden> wrote:
> Is it important that they be grouped in the order specified by the key?
> If not, this should do (with C the categories and S the strings):
>
> (⊂[1]C∘.=∪C)/¨⊂S
>
> If they must be ordered, then this can do it:
>
> (⊂[1]C∘.=U[⍋U←∪C])/¨⊂S
>
> In addition, the categories don’t have to be numbers.
>
> Note that Dyalog’s (dyadic) key function is equivalent to this, with L being
> the operator’s left operand:
>
> L¨(⊂[1]C∘.=∪C)/¨⊂S
>
> Cheers,
> Louis
>
> On 05 Jul 2017, at 11:43, Elias Mårtenson <address@hidden> wrote:
>
> I have a list of strings, and a corresponding set of categorisations:
>
>       strings ← 'foo' 'bar' 'abc' 'def' 'ghi' 'jkl'
>       categories ← 1 1 0 2 1 0
>
> I now need to group these strings according to category. In other words,
> when applying operation X, I need the following output:
>
>       categories X strings
> ┏→━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┓
> ┃┏→━━━━━━━━━━┓ ┏→━━━━━━━━━━━━━━━━┓ ┏→━━━━┓┃
> ┃┃"abc" "jkl"┃ ┃"foo" "bar" "hgi"┃ ┃"def"┃┃
> ┃┗∊━━━━━━━━━━┛ ┗∊━━━━━━━━━━━━━━━━┛ ┗∊━━━━┛┃
> ┗∊∊━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┛
>
> What is the best way to solve this?
>
>