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Quoting and HTML-like labels
----------------------------
The graph-building methods of :class:`.Graph` and :class:`.Digraph` objects
automatically take care of quoting (and escaping quotes) `where needed <DOT_>`_
(whitespace, keywords, double quotes, etc.):
.. doctest::
>>> import graphviz # doctest: +NO_EXE
>>> q = graphviz.Digraph()
>>> q.edge('spam', 'eggs eggs')
>>> q.edge('node', '"here\'s a quote"')
>>> print(q.source) # doctest: +NORMALIZE_WHITESPACE
digraph {
spam -> "eggs eggs"
"node" -> "\"here's a quote\""
}
If a string starts with ``'<'`` and ends with ``'>'``,
it is passed on **as is**, i.e. without quoting/escaping:
The content between the angle brackets is treated by
the Graphviz_ layout `engine <DOT layouts_>`_ as special **HTML string**
that can be used for `HTML-like labels <DOT shapes HTML_>`_:
.. doctest::
>>> h = graphviz.Graph('html_table') # doctest: +NO_EXE
>>> h.node('tab', label='''<<TABLE>
... <TR>
... <TD>left</TD>
... <TD>right</TD>
... </TR>
... </TABLE>>''')
.. image:: _static/html_table.svg
:align: center
For strings that should literally begin with ``'<'`` and end with ``'>'``,
use the :func:`graphviz.nohtml` function to disable the special meaning of angled
parenthesis and apply normal quoting/escaping:
.. doctest::
>>> d = graphviz.Digraph('diamond', format='svg') # doctest: +NO_EXE
>>> d.node('diamond', label=graphviz.nohtml('<>'))
>>> print(d.source) # doctest: +NORMALIZE_WHITESPACE
digraph diamond {
diamond [label="<>"]
}
.. doctest::
>>> doctest_mark_exe() # skip this line
>>> d.render(directory='doctest-output').replace('\\', '/')
'doctest-output/diamond.gv.svg'
.. image:: _static/diamond.svg
:align: center
.. admonition:: Historical note
Before version ``0.8.2``,
the only workaround was to add leading or trailing space
(``label=' <>'``):
.. include:: _links.rst
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