API Reference¶

`Graph`	Graph source code in the DOT language.
`Digraph`	Directed graph source code in the DOT language.
`Source`	Verbatim DOT source code string to be rendered by Graphviz.
`graphviz.render`	Render file with Graphviz `engine` into `format`, return result filename.
`graphviz.pipe`	Return `data` piped through Graphviz `engine` into `format`.
`graphviz.unflatten`	Return DOT `source` piped through Graphviz unflatten preprocessor.
`graphviz.view`	Open filepath with its default viewing application (platform-specific).

Note

The two main classes Graph and Digraph (for creating undirected vs. directed graphs) have exactly the same API. Their division reflects the fact that both graph types cannot be mixed.

Graph¶

class graphviz.Graph(name=None, comment=None, filename=None, directory=None, format=None, engine=None, encoding='utf-8', graph_attr=None, node_attr=None, edge_attr=None, body=None, strict=False)[source]¶

Graph source code in the DOT language.

Parameters

name – Graph name used in the source code.
comment – Comment added to the first line of the source.
filename – Filename for saving the source (defaults to name + '.gv').
directory – (Sub)directory for source saving and rendering.
format – Rendering output format ('pdf', 'png', …).
engine – Layout command used ('dot', 'neato', …).
encoding – Encoding for saving the source.
graph_attr – Mapping of (attribute, value) pairs for the graph.
node_attr – Mapping of (attribute, value) pairs set for all nodes.
edge_attr – Mapping of (attribute, value) pairs set for all edges.
body – Iterable of verbatim lines to add to the graph body.
strict (bool) – Rendering should merge multi-edges.

Note

All parameters are optional and can be changed under their corresponding attribute name after instance creation.

attr(kw=None, _attributes=None, **attrs)¶

Add a general or graph/node/edge attribute statement.

Parameters

kw – Attributes target (None or 'graph', 'node', 'edge').
attrs – Attributes to be set (must be strings, may be empty).

See the usage examples in the User Guide.

clear(keep_attrs=False)¶

Reset content to an empty body, clear graph/node/egde_attr mappings.

Parameters: keep_attrs (bool) – preserve graph/node/egde_attr mappings

copy()¶

Return a copied instance of the object.

Returns: An independent copy of the current object.

property directed¶: False

edge(tail_name, head_name, label=None, _attributes=None, **attrs)¶

Create an edge between two nodes.

Parameters

tail_name – Start node identifier (format: node[:port[:compass]]).
head_name – End node identifier (format: node[:port[:compass]]).
label – Caption to be displayed near the edge.
attrs – Any additional edge attributes (must be strings).

Note

The tail_name and head_name strings are separated by (optional) colon(s) into node name, port name, and compass (e.g. sw). See details in the User Guide.

edges(tail_head_iter)¶

Create a bunch of edges.

Parameters

tail_head_iter – Iterable of (tail_name, head_name) pairs
(format – node[:port[:compass]]).

Note

The tail_name and head_name strings are separated by (optional) colon(s) into node name, port name, and compass (e.g. sw). See details in the User Guide.

property encoding¶: The encoding for the saved source file.

property engine¶: The layout commmand used for rendering ('dot', 'neato', …).

property format¶: The output format used for rendering ('pdf', 'png', …).

node(name, label=None, _attributes=None, **attrs)¶

Create a node.

Parameters

name – Unique identifier for the node inside the source.
label – Caption to be displayed (defaults to the node name).
attrs – Any additional node attributes (must be strings).

pipe(format=None, renderer=None, formatter=None, quiet=False)¶

Return the source piped through the Graphviz layout command.

Parameters

format – The output format used for rendering ('pdf', 'png', etc.).
renderer – The output renderer used for rendering ('cairo', 'gd', …).
formatter – The output formatter used for rendering ('cairo', 'gd', …).
quiet (bool) – Suppress stderr output from the layout subprocess.

Returns

Binary (encoded) stdout of the layout command.

Raises

ValueError – If format, renderer, or formatter are not known.
graphviz.RequiredArgumentError – If formatter is given but renderer is None.
graphviz.ExecutableNotFound – If the Graphviz executable is not found.
subprocess.CalledProcessError – If the exit status is non-zero.

render(filename=None, directory=None, view=False, cleanup=False, format=None, renderer=None, formatter=None, quiet=False, quiet_view=False)¶

Save the source to file and render with the Graphviz engine.

Parameters

filename – Filename for saving the source (defaults to name + '.gv')
directory – (Sub)directory for source saving and rendering.
view (bool) – Open the rendered result with the default application.
cleanup (bool) – Delete the source file after rendering.
format – The output format used for rendering ('pdf', 'png', etc.).
renderer – The output renderer used for rendering ('cairo', 'gd', …).
formatter – The output formatter used for rendering ('cairo', 'gd', …).
quiet (bool) – Suppress stderr output from the layout subprocess.
quiet_view (bool) – Suppress stderr output from the viewer process (implies view=True, ineffective on Windows).

Returns

The (possibly relative) path of the rendered file.

Raises

ValueError – If format, renderer, or formatter are not known.
graphviz.RequiredArgumentError – If formatter is given but renderer is None.
graphviz.ExecutableNotFound – If the Graphviz executable is not found.
subprocess.CalledProcessError – If the exit status is non-zero.
RuntimeError – If viewer opening is requested but not supported.

The layout command is started from the directory of filepath, so that references to external files (e.g. [image=...]) can be given as paths relative to the DOT source file.

save(filename=None, directory=None)¶

Save the DOT source to file. Ensure the file ends with a newline.

Parameters

filename – Filename for saving the source (defaults to name + '.gv')
directory – (Sub)directory for source saving and rendering.

Returns

The (possibly relative) path of the saved source file.

property source¶: The DOT source code as string.

subgraph(graph=None, name=None, comment=None, graph_attr=None, node_attr=None, edge_attr=None, body=None)¶

Add the current content of the given sole graph argument as subgraph or return a context manager returning a new graph instance created with the given (name, comment, etc.) arguments whose content is added as subgraph when leaving the context manager’s with-block.

Parameters

graph – An instance of the same kind (Graph, Digraph) as the current graph (sole argument in non-with-block use).
name – Subgraph name (with-block use).
comment – Subgraph comment (with-block use).
graph_attr – Subgraph-level attribute-value mapping (with-block use).
node_attr – Node-level attribute-value mapping (with-block use).
edge_attr – Edge-level attribute-value mapping (with-block use).
body – Verbatim lines to add to the subgraph body (with-block use).

See the usage examples in the User Guide.

When used as a context manager, the returned new graph instance uses strict=None and the parent graph’s values for directory, format, engine, and encoding by default.

Note

If the name of the subgraph begins with 'cluster' (all lowercase) the layout engine will treat it as a special cluster subgraph.

unflatten(stagger=None, fanout=False, chain=None)¶

Return a new Source instance with the source piped through the Graphviz unflatten preprocessor.

Parameters

stagger (int) – Stagger the minimum length of leaf edges between 1 and this small integer.
fanout (bool) – Fanout nodes with indegree = outdegree = 1 when staggering (requires stagger).
chain (int) – Form disconnected nodes into chains of up to this many nodes.

Returns

Prepocessed DOT source code (improved layout aspect ratio).

Return type

Source

Raises

graphviz.RequiredArgumentError – If fanout is given but stagger is None.
graphviz.ExecutableNotFound – If the Graphviz unflatten executable is not found.
subprocess.CalledProcessError – If the exit status is non-zero.

view(filename=None, directory=None, cleanup=False, quiet=False, quiet_view=False)¶

Save the source to file, open the rendered result in a viewer.

Parameters

filename – Filename for saving the source (defaults to name + '.gv')
directory – (Sub)directory for source saving and rendering.
cleanup (bool) – Delete the source file after rendering.
quiet (bool) – Suppress stderr output from the layout subprocess.
quiet_view (bool) – Suppress stderr output from the viewer process (ineffective on Windows).

Returns

The (possibly relative) path of the rendered file.

Raises

graphviz.ExecutableNotFound – If the Graphviz executable is not found.
subprocess.CalledProcessError – If the exit status is non-zero.
RuntimeError – If opening the viewer is not supported.

Short-cut method for calling render() with view=True.

Note

There is no option to wait for the application to close, and no way to retrieve the application’s exit status.

Digraph¶

class graphviz.Digraph(name=None, comment=None, filename=None, directory=None, format=None, engine=None, encoding='utf-8', graph_attr=None, node_attr=None, edge_attr=None, body=None, strict=False)[source]¶

Directed graph source code in the DOT language.

Parameters

name – Graph name used in the source code.
comment – Comment added to the first line of the source.
filename – Filename for saving the source (defaults to name + '.gv').
directory – (Sub)directory for source saving and rendering.
format – Rendering output format ('pdf', 'png', …).
engine – Layout command used ('dot', 'neato', …).
encoding – Encoding for saving the source.
graph_attr – Mapping of (attribute, value) pairs for the graph.
node_attr – Mapping of (attribute, value) pairs set for all nodes.
edge_attr – Mapping of (attribute, value) pairs set for all edges.
body – Iterable of verbatim lines to add to the graph body.
strict (bool) – Rendering should merge multi-edges.

Note

All parameters are optional and can be changed under their corresponding attribute name after instance creation.

attr(kw=None, _attributes=None, **attrs)¶

Add a general or graph/node/edge attribute statement.

Parameters

kw – Attributes target (None or 'graph', 'node', 'edge').
attrs – Attributes to be set (must be strings, may be empty).

See the usage examples in the User Guide.

clear(keep_attrs=False)¶

Reset content to an empty body, clear graph/node/egde_attr mappings.

Parameters: keep_attrs (bool) – preserve graph/node/egde_attr mappings

copy()¶

Return a copied instance of the object.

Returns: An independent copy of the current object.

property directed¶: True

edge(tail_name, head_name, label=None, _attributes=None, **attrs)¶

Create an edge between two nodes.

Parameters

tail_name – Start node identifier (format: node[:port[:compass]]).
head_name – End node identifier (format: node[:port[:compass]]).
label – Caption to be displayed near the edge.
attrs – Any additional edge attributes (must be strings).

Note

The tail_name and head_name strings are separated by (optional) colon(s) into node name, port name, and compass (e.g. sw). See details in the User Guide.

edges(tail_head_iter)¶

Create a bunch of edges.

Parameters

tail_head_iter – Iterable of (tail_name, head_name) pairs
(format – node[:port[:compass]]).

Note

The tail_name and head_name strings are separated by (optional) colon(s) into node name, port name, and compass (e.g. sw). See details in the User Guide.

property encoding¶: The encoding for the saved source file.

property engine¶: The layout commmand used for rendering ('dot', 'neato', …).

property format¶: The output format used for rendering ('pdf', 'png', …).

node(name, label=None, _attributes=None, **attrs)¶

Create a node.

Parameters

name – Unique identifier for the node inside the source.
label – Caption to be displayed (defaults to the node name).
attrs – Any additional node attributes (must be strings).

pipe(format=None, renderer=None, formatter=None, quiet=False)¶

Return the source piped through the Graphviz layout command.

Parameters

format – The output format used for rendering ('pdf', 'png', etc.).
renderer – The output renderer used for rendering ('cairo', 'gd', …).
formatter – The output formatter used for rendering ('cairo', 'gd', …).
quiet (bool) – Suppress stderr output from the layout subprocess.

Returns

Binary (encoded) stdout of the layout command.

Raises

ValueError – If format, renderer, or formatter are not known.
graphviz.RequiredArgumentError – If formatter is given but renderer is None.
graphviz.ExecutableNotFound – If the Graphviz executable is not found.
subprocess.CalledProcessError – If the exit status is non-zero.

render(filename=None, directory=None, view=False, cleanup=False, format=None, renderer=None, formatter=None, quiet=False, quiet_view=False)¶

Save the source to file and render with the Graphviz engine.

Parameters

filename – Filename for saving the source (defaults to name + '.gv')
directory – (Sub)directory for source saving and rendering.
view (bool) – Open the rendered result with the default application.
cleanup (bool) – Delete the source file after rendering.
format – The output format used for rendering ('pdf', 'png', etc.).
renderer – The output renderer used for rendering ('cairo', 'gd', …).
formatter – The output formatter used for rendering ('cairo', 'gd', …).
quiet (bool) – Suppress stderr output from the layout subprocess.
quiet_view (bool) – Suppress stderr output from the viewer process (implies view=True, ineffective on Windows).

Returns

The (possibly relative) path of the rendered file.

Raises

ValueError – If format, renderer, or formatter are not known.
graphviz.RequiredArgumentError – If formatter is given but renderer is None.
graphviz.ExecutableNotFound – If the Graphviz executable is not found.
subprocess.CalledProcessError – If the exit status is non-zero.
RuntimeError – If viewer opening is requested but not supported.

The layout command is started from the directory of filepath, so that references to external files (e.g. [image=...]) can be given as paths relative to the DOT source file.

save(filename=None, directory=None)¶

Save the DOT source to file. Ensure the file ends with a newline.

Parameters

filename – Filename for saving the source (defaults to name + '.gv')
directory – (Sub)directory for source saving and rendering.

Returns

The (possibly relative) path of the saved source file.

property source¶: The DOT source code as string.

subgraph(graph=None, name=None, comment=None, graph_attr=None, node_attr=None, edge_attr=None, body=None)¶

Add the current content of the given sole graph argument as subgraph or return a context manager returning a new graph instance created with the given (name, comment, etc.) arguments whose content is added as subgraph when leaving the context manager’s with-block.

Parameters

graph – An instance of the same kind (Graph, Digraph) as the current graph (sole argument in non-with-block use).
name – Subgraph name (with-block use).
comment – Subgraph comment (with-block use).
graph_attr – Subgraph-level attribute-value mapping (with-block use).
node_attr – Node-level attribute-value mapping (with-block use).
edge_attr – Edge-level attribute-value mapping (with-block use).
body – Verbatim lines to add to the subgraph body (with-block use).

See the usage examples in the User Guide.

When used as a context manager, the returned new graph instance uses strict=None and the parent graph’s values for directory, format, engine, and encoding by default.

Note

If the name of the subgraph begins with 'cluster' (all lowercase) the layout engine will treat it as a special cluster subgraph.

unflatten(stagger=None, fanout=False, chain=None)¶

Return a new Source instance with the source piped through the Graphviz unflatten preprocessor.

Parameters

stagger (int) – Stagger the minimum length of leaf edges between 1 and this small integer.
fanout (bool) – Fanout nodes with indegree = outdegree = 1 when staggering (requires stagger).
chain (int) – Form disconnected nodes into chains of up to this many nodes.

Returns

Prepocessed DOT source code (improved layout aspect ratio).

Return type

Source

Raises

graphviz.RequiredArgumentError – If fanout is given but stagger is None.
graphviz.ExecutableNotFound – If the Graphviz unflatten executable is not found.
subprocess.CalledProcessError – If the exit status is non-zero.

view(filename=None, directory=None, cleanup=False, quiet=False, quiet_view=False)¶

Save the source to file, open the rendered result in a viewer.

Parameters

filename – Filename for saving the source (defaults to name + '.gv')
directory – (Sub)directory for source saving and rendering.
cleanup (bool) – Delete the source file after rendering.
quiet (bool) – Suppress stderr output from the layout subprocess.
quiet_view (bool) – Suppress stderr output from the viewer process (ineffective on Windows).

Returns

The (possibly relative) path of the rendered file.

Raises

graphviz.ExecutableNotFound – If the Graphviz executable is not found.
subprocess.CalledProcessError – If the exit status is non-zero.
RuntimeError – If opening the viewer is not supported.

Short-cut method for calling render() with view=True.

Note

There is no option to wait for the application to close, and no way to retrieve the application’s exit status.

Source¶

class graphviz.Source(source, filename=None, directory=None, format=None, engine=None, encoding='utf-8')[source]¶

Verbatim DOT source code string to be rendered by Graphviz.

Parameters

source – The verbatim DOT source code string.
filename – Filename for saving the source (defaults to 'Source.gv').
directory – (Sub)directory for source saving and rendering.
format – Rendering output format ('pdf', 'png', …).
engine – Layout command used ('dot', 'neato', …).
encoding – Encoding for saving the source.

Note

All parameters except source are optional. All of them can be changed under their corresponding attribute name after instance creation.

copy()¶

Return a copied instance of the object.

Returns: An independent copy of the current object.

property encoding¶: The encoding for the saved source file.

property engine¶: The layout commmand used for rendering ('dot', 'neato', …).

property format¶: The output format used for rendering ('pdf', 'png', …).

classmethod from_file(filename, directory=None, format=None, engine=None, encoding='utf-8')[source]¶

Return an instance with the source string read from the given file.

Parameters

filename – Filename for loading/saving the source.
directory – (Sub)directory for source loading/saving and rendering.
format – Rendering output format ('pdf', 'png', …).
engine – Layout command used ('dot', 'neato', …).
encoding – Encoding for loading/saving the source.

pipe(format=None, renderer=None, formatter=None, quiet=False)¶

Return the source piped through the Graphviz layout command.

Parameters

format – The output format used for rendering ('pdf', 'png', etc.).
renderer – The output renderer used for rendering ('cairo', 'gd', …).
formatter – The output formatter used for rendering ('cairo', 'gd', …).
quiet (bool) – Suppress stderr output from the layout subprocess.

Returns

Binary (encoded) stdout of the layout command.

Raises

ValueError – If format, renderer, or formatter are not known.
graphviz.RequiredArgumentError – If formatter is given but renderer is None.
graphviz.ExecutableNotFound – If the Graphviz executable is not found.
subprocess.CalledProcessError – If the exit status is non-zero.

render(filename=None, directory=None, view=False, cleanup=False, format=None, renderer=None, formatter=None, quiet=False, quiet_view=False)¶

Save the source to file and render with the Graphviz engine.

Parameters

filename – Filename for saving the source (defaults to name + '.gv')
directory – (Sub)directory for source saving and rendering.
view (bool) – Open the rendered result with the default application.
cleanup (bool) – Delete the source file after rendering.
format – The output format used for rendering ('pdf', 'png', etc.).
renderer – The output renderer used for rendering ('cairo', 'gd', …).
formatter – The output formatter used for rendering ('cairo', 'gd', …).
quiet (bool) – Suppress stderr output from the layout subprocess.
quiet_view (bool) – Suppress stderr output from the viewer process (implies view=True, ineffective on Windows).

Returns

The (possibly relative) path of the rendered file.

Raises

ValueError – If format, renderer, or formatter are not known.
graphviz.RequiredArgumentError – If formatter is given but renderer is None.
graphviz.ExecutableNotFound – If the Graphviz executable is not found.
subprocess.CalledProcessError – If the exit status is non-zero.
RuntimeError – If viewer opening is requested but not supported.

The layout command is started from the directory of filepath, so that references to external files (e.g. [image=...]) can be given as paths relative to the DOT source file.

save(filename=None, directory=None)¶

Save the DOT source to file. Ensure the file ends with a newline.

Parameters

filename – Filename for saving the source (defaults to name + '.gv')
directory – (Sub)directory for source saving and rendering.

Returns

The (possibly relative) path of the saved source file.

source¶: The verbatim DOT source code string.

unflatten(stagger=None, fanout=False, chain=None)¶

Return a new Source instance with the source piped through the Graphviz unflatten preprocessor.

Parameters

stagger (int) – Stagger the minimum length of leaf edges between 1 and this small integer.
fanout (bool) – Fanout nodes with indegree = outdegree = 1 when staggering (requires stagger).
chain (int) – Form disconnected nodes into chains of up to this many nodes.

Returns

Prepocessed DOT source code (improved layout aspect ratio).

Return type

Source

Raises

graphviz.RequiredArgumentError – If fanout is given but stagger is None.
graphviz.ExecutableNotFound – If the Graphviz unflatten executable is not found.
subprocess.CalledProcessError – If the exit status is non-zero.

view(filename=None, directory=None, cleanup=False, quiet=False, quiet_view=False)¶

Save the source to file, open the rendered result in a viewer.

Parameters

filename – Filename for saving the source (defaults to name + '.gv')
directory – (Sub)directory for source saving and rendering.
cleanup (bool) – Delete the source file after rendering.
quiet (bool) – Suppress stderr output from the layout subprocess.
quiet_view (bool) – Suppress stderr output from the viewer process (ineffective on Windows).

Returns

The (possibly relative) path of the rendered file.

Raises

graphviz.ExecutableNotFound – If the Graphviz executable is not found.
subprocess.CalledProcessError – If the exit status is non-zero.
RuntimeError – If opening the viewer is not supported.

Short-cut method for calling render() with view=True.

Note

There is no option to wait for the application to close, and no way to retrieve the application’s exit status.

Low-level functions¶

The functions in this section are provided to work directly with existing files and strings instead of using the object-oriented DOT creation methods documented above.

graphviz.render(engine, format, filepath, renderer=None, formatter=None, quiet=False)[source]¶

Render file with Graphviz engine into format, return result filename.

Parameters

engine – The layout commmand used for rendering ('dot', 'neato', …).
format – The output format used for rendering ('pdf', 'png', …).
filepath – Path to the DOT source file to render.
renderer – The output renderer used for rendering ('cairo', 'gd', …).
formatter – The output formatter used for rendering ('cairo', 'gd', …).
quiet (bool) – Suppress stderr output from the layout subprocess.

Returns

The (possibly relative) path of the rendered file.

Raises

ValueError – If engine, format, renderer, or formatter are not known.
graphviz.RequiredArgumentError – If formatter is given but renderer is None.
graphviz.ExecutableNotFound – If the Graphviz executable is not found.
subprocess.CalledProcessError – If the exit status is non-zero.

The layout command is started from the directory of filepath, so that references to external files (e.g. [image=...]) can be given as paths relative to the DOT source file.

graphviz.pipe(engine, format, data, renderer=None, formatter=None, quiet=False)[source]¶

Return data piped through Graphviz engine into format.

Parameters

engine – The layout commmand used for rendering ('dot', 'neato', …).
format – The output format used for rendering ('pdf', 'png', …).
data – The binary (encoded) DOT source string to render.
renderer – The output renderer used for rendering ('cairo', 'gd', …).
formatter – The output formatter used for rendering ('cairo', 'gd', …).
quiet (bool) – Suppress stderr output from the layout subprocess.

Returns

Binary (encoded) stdout of the layout command.

Raises

ValueError – If engine, format, renderer, or formatter are not known.
graphviz.RequiredArgumentError – If formatter is given but renderer is None.
graphviz.ExecutableNotFound – If the Graphviz executable is not found.
subprocess.CalledProcessError – If the exit status is non-zero.

graphviz.unflatten(source, stagger=None, fanout=False, chain=None, encoding='utf-8')[source]¶

Return DOT source piped through Graphviz unflatten preprocessor.

Parameters

source (str) – The DOT source to process (improve layout aspect ratio).
stagger (int) – Stagger the minimum length of leaf edges between 1 and this small integer.
fanout (bool) – Fanout nodes with indegree = outdegree = 1 when staggering (requires stagger).
chain (int) – Form disconnected nodes into chains of up to this many nodes.
encoding – Encoding used to encode unflatten stdin and decode its stdout.

Returns

Decoded stdout of the Graphviz unflatten command.

Return type

str

Raises

graphviz.RequiredArgumentError – If fanout is given but stagger is None.
graphviz.ExecutableNotFound – If the Graphviz unflatten executable is not found.
subprocess.CalledProcessError – If the exit status is non-zero.

graphviz.view(filepath, quiet=False)[source]¶

Open filepath with its default viewing application (platform-specific).

Parameters

filepath – Path to the file to open in viewer.
quiet (bool) – Suppress stderr output from the viewer process (ineffective on Windows).

Raises

RuntimeError – If the current platform is not supported.

Note

There is no option to wait for the application to close, and no way to retrieve the application’s exit status.

Other¶

graphviz.ExecutableNotFound[source]¶: Exception raised if the Graphviz executable is not found.

graphviz.RequiredArgumentError[source]¶: Exception raised if a required argument is missing.

graphviz.version()[source]¶

Return the version number tuple from the stderr output of dot -V.

Returns

Two, three, or four int version tuple.

Raises

graphviz.ExecutableNotFound – If the Graphviz executable is not found.
subprocess.CalledProcessError – If the exit status is non-zero.
RuntimmeError – If the output cannot be parsed into a version number.

Note

Ignores the ~dev.<YYYYmmdd.HHMM> portion of development versions.

graphviz.escape(s)[source]¶

Return s as literal disabling special meaning of backslashes and '<...>'.

Parameters: s – String in which backslashes and '<...>' should be treated as literal.
Raises: TypeError – If s is not a str on Python 3, or a str/unicode on Python 2.

>>> print(escape(r'\l'))
\\l

graphviz.nohtml(s)[source]¶

Return copy of s that will not treat '<...>' as DOT HTML string in quoting.

Parameters: s – String in which leading '<' and trailing '>' should be treated as literal.
Raises: TypeError – If s is not a str on Python 3, or a str/unicode on Python 2.

>>> quote('<>-*-<>')
'<>-*-<>'

>>> quote(nohtml('<>-*-<>'))
'"<>-*-<>"'

Manually maintained whitelists (see https://graphviz.gitlab.io/_pages/pdf/dot.1.pdf, http://www.graphviz.org/doc/info/output.html, and dot -T: output):

graphviz.ENGINES¶: Set of known layout commands used for rendering ('dot', 'neato', …)

graphviz.FORMATS¶: Set of known output formats for rendering ('pdf', 'png', …)

graphviz.RENDERERS¶: Set of known output renderers for rendering ('cairo', 'gd', …)

graphviz.FORMATTERS¶: Set of known output formatters for rendering ('cairo', 'gd', …)