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08:53
Really nice TIL: y[g] f←y, where g groups or classifies elements of y, will effectively perform a groupwise reduction, i.e. y[∪g]←∊f⌿¨g⊢∘⊂⌸y. In particular, we can do a groupwise version of @Adám's ∨⌿ above with y[g]∨←y.
09:17
@B.Wilson Indeed, an this nice feature makes it all the more frustrating that 1+@1 3 3⊢10 10 10 gives 11 10 11 rather than 11 10 12.
otoh, 1⌽@2 3 4⊢'abcd' giving 'acdb' is nice, whereas t←'abcd' ⋄ t[2 3 4]⌽⍨←1 ⋄ t does nothing.
 
6 hours later…
15:41
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16:10
@Adám really? i'd've expected that to work
(i don't really use bracket assignment)
@RubenVerg t[2 3 4]⌽⍨←1 working conflicts with t[2 3 3]+←1 working
@RubenVerg Well done.

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