+While trying to get a deeper understanding for the source of the build
+system [[http://www.scons.org SCons]], I actually wanted to see the classes
+and their dependencies. Googling around I found these two tools that could
+produce DOT graph files for class or import dependencies from Python source trees.
+~[[http://furius.ca/snakefood snakefood]]||Creates module import dependency graphs. Use the Mercurial command %%hg clone https://hg.furius.ca/public/snakefood%% for a checkout of the current sources.
+~[[http://www.logilab.org/project/pylint pyreverse]]||As part of pylint it analyzes class dependencies.
+Unfortunately, the resulting graphs were pretty large and visualizing them via
+the $$dot$$ tool did not help. PNG, PS or SVG output, the images got too large and
+the layout of the nodes and edges left a lot to desire (Example: SCons dependencies
+in [[scons.ps Postscript]] and [[scons.svg SVG]] format).
+Then I remembered the [[http://www.yworks.com/en/products_yed_about.html yEd graph editor]], a
+great application that can layout and handle even very large datasets...if you find a
+way to get the data inside. Since it does not import DOT files (yet), I wrote this
+little converter script that outputs yEd's native file format Graphml (XML).
+Now looking at complicated DOT graphs is a snap...have a try!
+== Current version == current
+~[[dottoxml.zip dottoxml.zip]]||Archived folder with the Python scripts for $$dottoxml$$.
+The following screenshots are not from a dependency analysis but a profiling
+of [[http://scons.tigris.org SCons]] at runtime. Using a combination of
+[[http://code.google.com/p/jrfonseca/wiki/Gprof2Dot $$Gprof2Dot$$]] and [[http://www.graphviz.org Graphviz DOT]],
+Nitro Zark has published the results of his investigations on
+[[http://nitrozark.free.fr/scons/bench1/benchmark-gfw-20090702.html his webpage]]. I picked the file $$benchgen-full-dry-run.dot$$
+because it uses colors to a great extent, which gives a nice looking graph.
+Start the script with the ''-h'' or ''--help'' option and the
+full set of available commands is displayed.
+The straightforward way to create a Graphml file out of a DOT is:
+python dottoxml.py infile.dot outfile.graphml
+Then open the new Graphml file in the [[http://www.yworks.com/en/products_yed_about.html yEd editor]]. The nodes of the
+graph are now all centered to the origin and have a standard size of
+[[yed1.png <<yed1.png||alt="Centered nodes" width="100%">>]]
+Change the latter by using the ''Tools'' menu in yEd and select the
+entry ''Fit Nodes to Label''. This feature adapts the size of each node
+to the text that is displayed within.
+[[yed1.png <<yed2.png||alt="Fitted nodes" width="100%">>]]
+Now you can select one of the automatic layout strategies from the ''Layout''
+menu. Often, one or two dialogs with special options appear.
+[[yed3.png <<yed3.png||alt="Options dialog" width="100%">>]]
+with the default settings and click OK. The nodes in the graph are then
+rearranged, according to your selected strategy. Here we see the
+layout ''Hierarchical, classic'':
+[[yed4.png <<yed4.png||alt="Full graph" width="100%">>]]
+And another time, in a randomly chosen closeup:
+[[yed5.png <<yed5.png||alt="Closeup" width="100%">>]]
+For further advice about the display or editing of graphs in [[http://www.yworks.com/en/products_yed_about.html yEd]],
+refer to its manual please.
+== Color options == colors
+In the screenshots above, the nodes are colored because the DOT file contained the necessary
+attribute statements. The $$dottoxml$$ script tries to pick up as much information as possible from the
+input file, not only colors but also arrow shapes (''arrow'' vs. ''diamond'') for example.
+If no color information is present in the DOT file, $$dottoxml$$ falls back to its defaults
+which are: some sort of grey (#CCCCFF) for the node background, and black (#000000) for the outline,
+the labels and the arrows.
+[[yed6.png <<yed6.png||alt="Default colors" width="100%">>]]
+You can override the default colors with the four commandline options:
+~$$--cn$$|| Node background color
+~$$--cnt$$|| Node label color
+~$$--cet$$|| Edge label color
+python dottoxml.py --cn #FF0000 infile.dot outfile.graphml
+sets the standard node background to a pure ''red''. Instead of
+giving RGB triplets, you can also specify an X11 color name like this:
+python dottoxml.py --cn blanchedalmond infile.dot outfile.graphml
+[[yed7.png <<yed7.png||alt="Blanched almond" width="100%">>]]
+== Other specials == specials
+Very simple graphs often contain only the node labels and the edge information
+itself, but no labels for the edges. With the option ''$$--ae$$'' you can enable
+the ''Auto labeling''. This means that for every edge that does not provide its
+own label, $$dottoxml$$ generates one of the form
+source_node_label -> destination_node_label
+When analyzing dependencies, there may appear single nodes that are ''isolated''
+from the rest of the graph and have no outgoing or incoming edges at all.
+If you want to see only ''connected'' nodes, you can enable the ''sweep'' option ''$$-s$$''.
+The script then filters out all single nodes and does not output them to the Graphml file.
+Finally, a very special option for the work with UML nodes that also contain the names
+of attributes and methods for a class. If you activate the ''Fit Label to Nodes'' feature
+in yEd, the nodes are expanded only around the class name (=label) but not the methods.
+As a workaround you can enable the ''lumping attributes'' option ''$$--la$$'', which
+collects all the text data for the UML node and puts it into the label. The single
+sections are divided by separators, built with the ''separator char'' given by the ''$$--sc$$''
+== Restrictions == restrict
+This script is still under development and far from stable! Please note the following
+remarks and restrictions:
+#At the moment, the DOT parser is very simple and line-based. It detects only node and
+edge lines, no subgraphs are handled. Node and edge specifications must be in a single
+#I tried to do my best, but the whole encoding part (Unicode support and detection of
+input encoding) still appears to be a little bit ''shaky'' to me. Do not expect too much
+== More examples == more
+More examples and screenshots can be found at the [[http://scons.org/wiki/VisualizeDependencies VisualizeDependencies]] page in the
+[[http://scons.org/wiki SCons Wiki]]...