Visualizing syntax graphs with Mermaid

Mermaid is a lightweight diagramming language that is easily used in many Markdown viewers and editors, web environments, the https://mermaid.live mermaid editor, and others. To compose a Mermaid diagram for a token graph:

from arsgrammatica import tokengraph_to_mermaid
diagram, warnings = tokengraph_to_mermaid(result.tokengraph)

warnings lists any edge that got skipped because it pointed at a punctuation token or an id missing from tokengraph.

You can save the diagram to a file with save_mermaid.

from arsgrammatica import save_mermaid
save_mermaid(diagram,"diagram.mmd")

Both tokengraph_to_mermaid and save_mermaid accept one of Mermaid’s orientation codes (BT, TB, LR, RL) in an optional orientation argument, with default value BT (bottom-to-top). Remember that the token graph is directed from subordinate to governing nodes. BT will result in root elements at the top, and RL will place root elements at the left of the diagram.

diagram, warnings = tokengraph_to_mermaid(
    result.tokengraph, 
    orientation="RL")

Limitations

Mermaid’s layout engine cannot enforce aligning nodes by rank. (You can think of rank as the syntactic depth of the node, like the generations in a family tree.) This kind of alignment can make the diagram of very complex sentences easier to read. If you want diagrams aligned by rank, you can use the open-source graphviz program: see “Diagramming syntactic analyses”.