#+TITLE: Ontology Visualization

• Example #+BEGIN_SRC bash ./ontology_viz.py -o test.dot test.ttl -O ontology.ttl dot -Tpng -o test.png test.dot #+END_SRC

• Use -o to indicate the path of output file
• Use -O to indicate the input ontology (Optional).
• Use -C to indicate the configuration file (Optional).
  • max_label_length: config the max length of labels. If the text exceeds the length, exceeded part will be replaced with "...". Default value is 0.
  • blacklist: config the predicate that you don't want to see in the graph.
  • class_inference_in_object: config the predicate that can inference the object is a Class, even if the class doesn't defined in the ontology.
  • label_property: config the predicate that used for labeling nodes, if such a label exists, it will display inside the node.
  • tooltip_property: config the predicate that contains the tooltip texts.
  • bnode_regex: a list of regexes, if an uri matches, then it will be dispaly as a blank node without its uri nor label. It can be useful if you have a lot of reifications.
  • colors: config the colors of nodes

    • class, literal, instance can accept HEX value(e.g. "#ff0000" ), MATLAB style(e.g. "r" ), and color name (e.g. "red" ). #+BEGIN_SRC json "colors": { "class": "#ff0000", "literal": "r", "instance": "red", } #+END_SRC

    • instance can also accept a dict value to specify the color of each class instance. And use "default" to to set color for undefined instances. #+BEGIN_SRC json "instance": { "https://tac.nist.gov/tracks/SM-KBP/2018/ontologies/SeedlingOntology#Facility": "#a6cee3", "default": "#ffff99" } #+END_SRC

    • filled: config whether fill the node, default value: true.

• Classes defined in the ontology will be omitted in the output graph. This action can be switched with argument -V.

** Useful Graphviz flags

• -K to specify which [[https://graphviz.gitlab.io/_pages/pdf/dot.1.pdf][layout algorithm]] to use. E.g. -Kneato and -Ksfdp . Notice that inorder to use sfdp layout algorithm, you will need to build your graphviz with [[http://gts.sourceforge.net][GTS]].
• -T to specify the [[https://graphviz.gitlab.io/_pages/doc/info/output.html][output format]].
• -G to set a [[https://graphviz.gitlab.io/_pages/doc/info/attrs.html][graph attribute]]. E.g. -Goverlap=prism

• Requirements In order to use this tool, you'll need to make sure you have [[https://github.com/RDFLib/rdflib][rdflib]] installed.

In order to convert =dot= into =png= or =svg= image, you will need [[https://www.graphviz.org][Graphviz]].