:mod:`altgraph.Dot` --- Interface to the dot language
=====================================================
.. module:: altgraph.Dot
:synopsis: Interface to the dot language as used by Graphviz..
The :py:mod:`~altgraph.Dot` module provides a simple interface to the
file format used in the `graphviz`_ program. The module is intended to
offload the most tedious part of the process (the **dot** file generation)
while transparently exposing most of its features.
.. _`graphviz`: <http://www.research.att.com/sw/tools/graphviz/>`_
To display the graphs or to generate image files the `graphviz`_
package needs to be installed on the system, moreover the :command:`dot` and :command:`dotty` programs must
be accesible in the program path so that they can be ran from processes spawned
within the module.
Example usage
-------------
Here is a typical usage::
from altgraph import Graph, Dot
# create a graph
edges = [ (1,2), (1,3), (3,4), (3,5), (4,5), (5,4) ]
graph = Graph.Graph(edges)
# create a dot representation of the graph
dot = Dot.Dot(graph)
# display the graph
dot.display()
# save the dot representation into the mydot.dot file
dot.save_dot(file_name='mydot.dot')
# save dot file as gif image into the graph.gif file
dot.save_img(file_name='graph', file_type='gif')
Directed graph and non-directed graph
-------------------------------------
Dot class can use for both directed graph and non-directed graph
by passing *graphtype* parameter.
Example::
# create directed graph(default)
dot = Dot.Dot(graph, graphtype="digraph")
# create non-directed graph
dot = Dot.Dot(graph, graphtype="graph")
Customizing the output
----------------------
The graph drawing process may be customized by passing
valid :command:`dot` parameters for the nodes and edges. For a list of all
parameters see the `graphviz`_ documentation.
Example::
# customizing the way the overall graph is drawn
dot.style(size='10,10', rankdir='RL', page='5, 5' , ranksep=0.75)
# customizing node drawing
dot.node_style(1, label='BASE_NODE',shape='box', color='blue' )
dot.node_style(2, style='filled', fillcolor='red')
# customizing edge drawing
dot.edge_style(1, 2, style='dotted')
dot.edge_style(3, 5, arrowhead='dot', label='binds', labelangle='90')
dot.edge_style(4, 5, arrowsize=2, style='bold')
.. note::
dotty (invoked via :py:func:`~altgraph.Dot.display`) may not be able to
display all graphics styles. To verify the output save it to an image
file and look at it that way.
Valid attributes
----------------
- dot styles, passed via the :py:meth:`Dot.style` method::
rankdir = 'LR' (draws the graph horizontally, left to right)
ranksep = number (rank separation in inches)
- node attributes, passed via the :py:meth:`Dot.node_style` method::
style = 'filled' | 'invisible' | 'diagonals' | 'rounded'
shape = 'box' | 'ellipse' | 'circle' | 'point' | 'triangle'
- edge attributes, passed via the :py:meth:`Dot.edge_style` method::
style = 'dashed' | 'dotted' | 'solid' | 'invis' | 'bold'
arrowhead = 'box' | 'crow' | 'diamond' | 'dot' | 'inv' | 'none' | 'tee' | 'vee'
weight = number (the larger the number the closer the nodes will be)
- valid `graphviz colors <http://www.research.att.com/~erg/graphviz/info/colors.html>`_
- for more details on how to control the graph drawing process see the
`graphviz reference <http://www.research.att.com/sw/tools/graphviz/refs.html>`_.
Class interface
---------------
.. class:: Dot(graph[, nodes[, edgefn[, nodevisitor[, edgevisitor[, name[, dot[, dotty[, neato[, graphtype]]]]]]]]])
Creates a new Dot generator based on the specified
:class:`Graph <altgraph.Graph.Graph>`. The Dot generator won't reference
the *graph* once it is constructed.
If the *nodes* argument is present it is the list of nodes to include
in the graph, otherwise all nodes in *graph* are included.
If the *edgefn* argument is present it is a function that yields the
nodes connected to another node, this defaults to
:meth:`graph.out_nbr <altgraph.Graph.Graph.out_nbr>`. The constructor won't
add edges to the dot file unless both the head and tail of the edge
are in *nodes*.
If the *name* is present it specifies the name of the graph in the resulting
dot file. The default is ``"G"``.
The functions *nodevisitor* and *edgevisitor* return the default style
for a given edge or node (both default to functions that return an empty
style).
The arguments *dot*, *dotty* and *neato* are used to pass the path to
the corresponding `graphviz`_ command.
Updating graph attributes
.........................
.. method:: Dot.style(\**attr)
Sets the overall style (graph attributes) to the given attributes.
See `Valid Attributes`_ for more information about the attributes.
.. method:: Dot.node_style(node, \**attr)
Sets the style for *node* to the given attributes.
This method will add *node* to the graph when it isn't already
present.
See `Valid Attributes`_ for more information about the attributes.
.. method:: Dot.all_node_style(\**attr)
Replaces the current style for all nodes
.. method:: edge_style(head, tail, \**attr)
Sets the style of an edge to the given attributes. The edge will
be added to the graph when it isn't already present, but *head*
and *tail* must both be valid nodes.
See `Valid Attributes`_ for more information about the attributes.
Emitting output
...............
.. method:: Dot.display([mode])
Displays the current graph via dotty.
If the *mode* is ``"neato"`` the dot file is processed with
the neato command before displaying.
This method won't return until the dotty command exits.
.. method:: save_dot(filename)
Saves the current graph representation into the given file.
.. note::
For backward compatibility reasons this method can also
be called without an argument, it will then write the graph
into a fixed filename (present in the attribute :data:`Graph.temp_dot`).
This feature is deprecated and should not be used.
.. method:: save_image(file_name[, file_type[, mode]])
Saves the current graph representation as an image file. The output
is written into a file whose basename is *file_name* and whose suffix
is *file_type*.
The *file_type* specifies the type of file to write, the default
is ``"gif"``.
If the *mode* is ``"neato"`` the dot file is processed with
the neato command before displaying.
.. note::
For backward compatibility reasons this method can also
be called without an argument, it will then write the graph
with a fixed basename (``"out"``).
This feature is deprecated and should not be used.
.. method:: iterdot()
Yields all lines of a `graphviz`_ input file (including line endings).
.. method:: __iter__()
Alias for the :meth:`iterdot` method.