Please add Union-Find

[pitr]

Suggested additional code entry (required)

I {p←⍺ ⋄ p⊣{p[⍵]←⍺}⍥({p[⍵]}⍣≡)/¨⍵} Xv

Description (required)
Union-find (aka disjoint-set, merge–find) algorithm to merge sets (represented as trees). I is a parent vector. Xv is a vector of tuples representing vertices to merge. Returns a parent vector with those vertices merged.

Class (optional)
Tacit

Type (optional)
Monadic Function

Group (optional)
Dyadic Operator, Monadic Operator

Category (required)
Sets, Trees

Keywords (optional)
union-find disjoint-set merge–find

TIO (optional)
Try it online URL

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[abrudz]

{I[⍵]←⍺}⍥({I[⍵]}⍣≡)/¨ is not a self-contained function, as it relies on updating a global I.

[pitr]

Thanks, I rewrote the function to be self-sustained by taking I as a parameter.

[abrudz]

Excellent. Can you also update the TIO link?

[pitr]

hmm, strange, in TIO what I was trying to do doesn't seem to work, the inner function seems to update a clone of the original function, see here. In my local Dyalog it works just fine. Any idea why this might be?