visiter 0.8.1

Build and visualize orbit graphs for discrete iterations under guarded rules.

VisIter

See what a discrete iteration actually does — as a graph.

The simplest case

Integers 1–9. Rule: divisible by 3 → divide by 3. Everything else → add 2. Where does each value end up?

echo 'range(1, 10), [Rule(lambda x: x%3==0, Op(lambda x: x//3))], Op(lambda x: x+2)' | viter

One line, auto-derived edge labels, SVG on stdout.

Install

pip install visiter

Graphviz must be available on PATH (brew install graphviz / apt install graphviz).

Going further

Put the iteration in a .vit file — shebang-executable, with comments:

#!/usr/bin/env viter
# descent graph, range 1–9
range(1, 10),
[Rule(lambda x: x%3==0, Op(lambda x: x//3, label="÷3"))],
Op(lambda x: x+2, label="+2")

chmod +x descent.vit
./descent.vit > descent.svg       # shebang
viter descent.vit -o descent.svg  # explicit

Crop the view around a node, render only what reaches it:

viter descent.vit --render 'anchor=1, radius=8, direction="backward"' -o crop.svg

Use the Python API instead of the CLI:

from visiter import iterate, Op, Rule, to_dot

graph = iterate(
    range(1, 10),
    [Rule(lambda x: x % 3 == 0, Op(lambda x: x // 3))],
    Op(lambda x: x + 2),
)
to_dot(graph).render("descent", format="svg")

Two entry points

• viter — one-shot: .vit file (or stdin) in, image out. Safe defaults (--max-nodes 10000, --time-limit 00:00:30) keep a typo'd rule from running away. Output goes to stdout or -o FILE.

• visiter — pipe-composable subcommands for full control:

  visiter build descent.vit | visiter to-dot 'anchor=1' | dot -Tsvg > out.svg
  

  build writes JSON; to-dot reads JSON, writes DOT; validate checks the JSON against the bundled schema; analyze bridges to NetworkX for graph algorithms.

Why VisIter?

Free, scriptable, Graphviz-native, Unix-pipe-composable orbit-graph rendering for discrete iterations under guarded rules — with cutoff boundaries (bounds, depth limits, render crops) as a first-class visual primitive, not silent truncation.

Full honest comparison against NetworkX, NestGraph (Mathematica), Maude, LoLA, and continuous-dynamics tooling: docs/comparison.md.

Documentation

• docs/tutorial.md — gentle introduction: what problem the tool solves, smallest example, what each piece does, what the dashed arrows mean. Start here.
• docs/manual.md — reference: every parameter, every data field, the rendering model in full, design decisions.
• docs/comparison.md — how VisIter relates to other tools in the ecosystem, and when to pick something else.
• demos/ — runnable end-to-end examples: make demo writes SVG/PDF/DOT into demos/out/.

License

MIT