Graphviz utility functions.

Latest release 20221118:

• quote: provide escape sequence for newline.
• DOTNodeMixin: provide .dot_node_id property, default str(id(self)).
• DOTNodeMixin.dot_node: omit [attrs] if they are empty.
• DOTNodeMixin: new .dot_node_palette_key property, new getattr for .dot_node_*color attributes, new empty default DOT_NODE_COLOR_PALETTE and DOT_NODE_FILLCOLOR_PALETTE class attributes.
• DOTNodeMixin.dot_node: include the node label in the attributes.
• Add colours to DOTNodeMixin.dot_node_attrs and fix "fontcolor".

See also the [https://www.graphviz.org/documentation/](graphviz documentation) and particularly the [https://graphviz.org/doc/info/lang.html](DOT language specification) and the [https://www.graphviz.org/doc/info/command.html](dot command line tool).

Class DOTNodeMixin

A mixin providing methods for things which can be drawn as nodes in a DOT graph description.

Function gvdata(dot_s, **kw)

Convenience wrapper for gvprint which returns the binary image data.

Function gvdataurl(dot_s, **kw)

Convenience wrapper for gvprint which returns the binary image data as a data: URL.

Function gvprint(dot_s, file=None, fmt=None, layout=None, dataurl_encoding=None, **dot_kw)

Print the graph specified by dot_s, a graph in graphViz DOT syntax, to file (default sys.stdout) in format fmt using the engine specified by layout (default 'dot').

If fmt is unspecified it defaults to 'png' unless file is a terminal in which case it defaults to 'sixel'.

In addition to being a file or file descriptor, file may also take the following special values:

• GVCAPTURE: causes gvprint to return the image data as bytes
• GVDATAURL: causes gvprint to return the image data as a data: URL

For GVDATAURL, the parameter dataurl_encoding may be used to override the default encoding, which is 'utf8' for fmt values 'dot' and 'svg', otherwise 'base64'.

This uses the graphviz utility dot to draw graphs. If printing in SIXEL format the img2sixel utility is required, see https://saitoha.github.io/libsixel/.

Example:

data_url = gvprint('digraph FOO {A->B}', file=GVDATAURL, fmt='svg')

Function quote(s)

Quote a string for use in DOT syntax. This implementation passes identifiers and sequences of decimal numerals through unchanged and double quotes other strings.

Release Log

Release 20221118:

• quote: provide escape sequence for newline.
• DOTNodeMixin: provide .dot_node_id property, default str(id(self)).
• DOTNodeMixin.dot_node: omit [attrs] if they are empty.
• DOTNodeMixin: new .dot_node_palette_key property, new getattr for .dot_node_*color attributes, new empty default DOT_NODE_COLOR_PALETTE and DOT_NODE_FILLCOLOR_PALETTE class attributes.
• DOTNodeMixin.dot_node: include the node label in the attributes.
• Add colours to DOTNodeMixin.dot_node_attrs and fix "fontcolor".

Release 20220827.1: gvprint: new optional parameter dataurl_encoding to specify the data URL encoding.

Release 20220827:

• Remove dependency on cs.lex - now we need only the stdlib.
• New GVCAPTURE value for gvprint(file=) to return the binary image data as a bytes object; associated gvdata() convenience function.
• New GVDATAURL value for gvprint(file=) to return the binary image data as a data URL; associated gvdataurl() convenience function.

Release 20220805.1: New DOTNodeMixin, a mixin for classes which can be rendered as a DOT node.

Release 20220805: Initial PyPI release.