pvec ← ##.stpaths tree                      ⍝ Spanning tree paths.

Returns  vector [pvec] of the paths from the root to each vertex of the spanning
[tree].

It  is  quicker  to extract single paths using →stpath← but if all paths are re-
quired, [stpaths] is quicker than {⍵∘stpath¨⍳⍴⍵}.

Examples:

⍝
⍝      Graph "a".
⍝    ┌─────1←────┐   5 vertices: 1 2 3 4 5
⍝    │     │     │
⍝    ↓     ↓     │   8 edges:    1→2  1→3
⍝    2←───→3────→4               2→3
⍝          ↑     │               3→2  3→4
⍝          │     ↓               4→1  4→5
⍝          └─────5               5→3

      a←(2 3)(3)(2 4)(1 5)(3)       ⍝ simple origin-1 graph.

      a span 1
¯1 1 1 3 4

      stpaths a span 1              ⍝ paths from vertex 1.
┌─┬───┬───┬─────┬───────┐
│1│1 2│1 3│1 3 4│1 3 4 5│
└─┴───┴───┴─────┴───────┘

See also: stpath stdists span Graphs

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