Graphviz

https://graphviz.org

Graphviz is open source graph visualization software. Graph visualization is a way of representing structural information as diagrams of abstract graphs and networks. It has important applications in networking, bioinformatics, software engineering, database and web design, machine learning, and in visual interfaces for other technical domains.

Starting in the middle of

• cover graph of the Aesthetic Programming book: https://aesthetic-programming.net/ (OSP, Winnie Soon, Geoff Cox)
• OSP workshop at Karlsruhe with etherdot: http://osp.kitchen/workshop/karlsruhe/ (June 2023)
• NeON's infrastructure observations, in Counter Cloud Action Plan by TITiPI for NeON https://titipi.org/wiki/index.php/Counter_Cloud_Action_Plan#Observations
• So-and-sovereignty diagrams (Martino Morandi and Femke Snelting/TITiPI) + https://gitlab.constantvzw.org/titipi/Tardigraph, source: https://gtr.ukri.org/projects?ref=AH%2FX006379%2F1

As part of Energy Giveaway at the Humuspunk Library, AIA, Zurich, interdependent artist/researcher Martino Morandi and Femke Snelting developped three diagrams. Thinking with nematodes and teletypes, with imbricated servers and institutional burrows, this shape-shifting diagram both traces and re-plots an ongoing conversation about modes of interdependence under the regime of The Cloud. The diagrams zoomed in on geometries and vocabularies that once seemed useful for limiting damage, creating solidarity and re-organizing collective resources, showing how they have been turned inside-out and are in need of a collective re-articulation of forms of togetherness.

• The Art of Asking Your Boss, by George Perec; described in Mainframe Experimentalism, by Hannah Higgins Chapter 2 + a radio version

what Perec discovered as he wrote out the “simultaneous” flowchart protocol was that time reinserts itself by necessity in any narrative, even when obstinately restricted to the present tense: the employee seeking a raise is a little older at each approach to his head of department whenever the arrows and choices take him back to the top of his chart. Because of this, the recursion cannot be infinite, because if algorithms exist without time, men do not, and must die. – Mainframe Experimentalism, by Hannah Higgins

• graphviz gallery https://graphviz.org/gallery/
• gradient examples https://graphviz.org/Gallery/gradient/
• dot-to-ascii web editor: https://dot-to-ascii.ggerganov.com/
• PythonGraphviz

Use graphviz

For example with dot:

$ dot hello.dot -Tpng -O

This reads the file hello.dot and renders the graph into a PNG image, which is saved with the same filename, but with the PNG extension: hello.dot.png.

To see all options of dot:

$ man dot

Nodes and edges

Graphviz works with the dot language, and works with graphs, nodes and edges.

You can change the type, color and behavior of these with attributes and shapes:

• graph attributes
• nodes attributes
• node shapes
• edge attributes

This page lists a range of examples: https://renenyffenegger.ch/notes/tools/Graphviz/examples/index

Layout engines

Graphviz comes with a set of different built-in layout engines and each of these render the graph differently:

• dot: hierarchical
• neato: spring
• circo: circular
• twopi: radial
• fdp: force-directed placement

Each of these are installed when you install graphviz. To use them, you change use the name of the layout engine as command in the CLI:

$ dot hello.dot -Tsvg -ofile hello.svg
$ neato hello.dot -Tsvg -ofile hello.svg
$ circo hello.dot -Tsvg -ofile hello.svg
$ twopi hello.dot -Tsvg -ofile hello.svg
$ fdp hello.dot -Tsvg -ofile hello.svg

You can check them all here: https://graphviz.org/docs/layouts/

Output formats

Graphviz uses a range of output formats, such as:

• svg
• png
• jpeg
• pdf

To change the output format, you change the -Tsvg part of your command:

$ dot hello.dot -Tsvg -ofile hello.svg
$ dot hello.dot -Tpng -ofile hello.svg
$ dot hello.dot -Tjpg -ofile hello.svg
$ dot hello.dot -Tpdf -ofile hello.svg

There is a list here: https://graphviz.org/docs/outputs/

What is nice when you export to svg is that you can use graphviz as an initial step in your workflow, and continue working on your diagram in other vector editing software, such as Inkscape or others. And! when saving as svg, your diagram stays a vector drawing, which also means you scale it, copy/paste it into a web page, and... pen plot it!

And about png: this is a good image file format if you want to render your diagram as a static image file, as it good for detailed line drawings and typography, and it support transparency.

dot language

Some examples.

You create edges with an "arrow": ->:

digraph {
  hello -> xpub
}

You can label an edge:

digraph {
  hello -> xpub [label="who?"]
}

You can use id's to assign attributes to a node:

digraph {

  A [label="Hello" shape=diamond]
  B [label="XPUB" shape=box]
  C [label="1" shape=circle]

  A -> B 
  A -> C 
  A -> D 

}

You can use subgraphs to create multiple edges in one go:

digraph {

  hello -> {XPUB1 XPUB2} 

}

And you can use attributes to render your diagram in a specific way/color/font/size/...:

digraph {

  /* set graph attributes here */
  bgcolor="yellow:pink"
  gradientangle=90

  /* set node attributes here */
  A [label="hello" style=filled color=blue fillcolor="lightgreen:lightyellow" gradientangle=0]
  B [label="xpub" style=filled]

  /* set edge attributes here */
  A -> B [color=purple]

}