tree.bqn

#
# Example of how to render an ascii tree from a parent vector
#
  Draw⇐{
    d←(⊢∾1+⊏⟜⥊)´⌽p←𝕩                                   # p: parent vector, d: depth vector
    w←{∾⍟(1-˜≡)(𝕨(⊣⊔˜⊏)p)⊸(⊢∾¨⊏˜)⌾((𝕩∊𝕨⊏p)⊸/)𝕩}´⌽d⊔↕≠p # order depths depending on parent groups
    n←(1+w⊏p)⊸∧˘(1+⌈´d)↑w=⌜w⊏d                         # matrix of ordered depth path cut off
    n↩(0≠∨˝n)⊸/˘n↩>(↕≠)⊸({«⍟𝕨 𝕩}˘)n                    # shift columns under parent node and remove empty space
    s←0<∊⊸∧˘n⋄e←0<(⌽∘∊∘⌽)⊸∧˘n⋄h←s+`∘-˘e⋄m←0<h∧n⋄v←s∧e  # s: start, e: ends, h: horizontals, m: middles, v: verticals 
    b←" ─┬├┐│"⊏˜(0⥊˜≠⍉n)∾1↓⌈´h‿m‿s‿e‿vר1+↕5           # branches - nullify root layer. 1: horizontal, 2: middle, 3: start, 4: end, 5: vertical, 
    o←∾˘(0⊸≢)◶" "‿"·"¨n                                # convert nodes to characters
    •Out˘b{𝕨∾(@+10)∾𝕩}˘o                               # combine branches and nodes and print
  }
  
Draw 0‿0‿1
Draw 0‿0‿0‿0
Draw 0‿0‿1‿0
Draw 0‿0‿1‿1‿0
Draw 0‿0‿1‿0‿1
Draw 0‿0‿0‿2‿2‿2
Draw 0‿0‿0‿2‿2‿2‿0
Draw 0‿0‿0‿2‿2‿2‿0‿0
Draw 0‿0‿1‿2‿0‿2‿0‿4‿2‿2‿4
Draw 0‿0‿1‿2‿0‿1‿0‿4‿1
Draw 0‿0‿1‿2‿3‿3‿3 
Draw 0‿0‿1‿2‿3‿4‿4‿4