Square Original Of (⊐)

⊐ 𝕩: Classify

Translate major cells of 𝕩 to unique ID numbers based on first occurrence.

       ⊐ 5‿6‿2‿2‿5‿1
⟨ 0 1 2 2 0 3 ⟩

       a ← 3‿3 ⥊ 0‿1‿2‿9‿0‿9‿0‿1‿2

       ⊐ a
⟨ 0 1 0 ⟩

𝕨 ⊐ 𝕩: Index Of

First index of each major cell of 𝕩 in 𝕨. Rank of 𝕩 must be at least cell rank of 𝕨.

If a cell is not found in 𝕨, the length of 𝕨 (≠𝕨) is used for that position.

       5‿6‿2‿2‿5‿1 ⊐ 5‿7‿1‿6
⟨ 0 6 5 1 ⟩

       b ← 3‿3 ⥊ 0‿1‿2‿9‿0‿9‿0‿1‿2

       b ⊐ ≍9‿0‿9
⟨ 1 ⟩