Subgraphs & clustersΒΆ
Graph
and Digraph
objects have a
subgraph()
method for adding a subgraph to the instance.
There are two ways to use it: Either with a ready-made instance
of the same kind as the only argument (whose content is added as a subgraph)
or omitting the graph
argument
(returning a context manager for defining the subgraph content more elegantly
within a with
-block).
First option, with graph
as the only argument:
>>> import graphviz
>>> p = graphviz.Graph(name='parent')
>>> p.edge('spam', 'eggs')
>>> c = graphviz.Graph(name='child', node_attr={'shape': 'box'})
>>> c.edge('foo', 'bar')
>>> p.subgraph(c)
Second usage, with a with
-block (omitting the graph
argument):
>>> p = graphviz.Graph('parent')
>>> p.edge('spam', 'eggs')
>>> with p.subgraph(name='child', node_attr={'shape': 'box'}) as c:
... c.edge('foo', 'bar')
Both produce the same result:
>>> print(p.source)
graph parent {
spam -- eggs
subgraph child {
node [shape=box]
foo -- bar
}
}
Tip
If the name
of a subgraph begins with 'cluster'
(all lowercase),
the layout engine treats it as a special cluster subgraph
(example ).
See the Subgraphs and Clusters section in DOT language.
When subgraph()
is used as a context manager,
the new graph instance is created with strict=None
copying the parent graph values for directory
,
engine
, format
, renderer
, formatter
,
and encoding
:
>>> doctest_mark_exe()
>>> p = graphviz.Graph('parent', directory='doctest-output')
>>> with p.subgraph(name='child') as c:
... c.edge('bacon', 'eggs')
... c.render().replace('\\', '/')
'doctest-output/child.gv.pdf'
Note
These copied attributes are only relevant for rendering the subgraph
independently (i.e. as a stand-alone graph) from within the with
-block.