Ask HN: How to visualize dependency graphs? | Hacker News Reader

Ask HN: How to visualize dependency graphs?

6 pointserlehmann_6 comments

My implementation of DJB redo [1] can output build dependency graphs that can be rendered with Graphviz. A recurring problem I have been having is that often, a target has many dependencies that share their dependencies, leading to unreadable graphs [2].

How could I create a readable dependency graph for such cases?

[1] http://news.dieweltistgarnichtso.net/bin/redo-sh.html [2] http://daten.dieweltistgarnichtso.net/pics/graphs/redo/liberation-circuit-deps.png

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It seems to me you should be able to put an integer on each dependency so that you can layer them in neat layers so the dependency arrows always point in the same direction.

I do not understand how your proposal would help. Could you elaborate on it and provide an example or a quick sketch?

How about this.

Give the "product" (which has nothing depending on it) the number 0, then the number for anything else is the length of the longest chain of dependencies from the root to the dependency in question.

You could put layer 0 on the far right, and then layer 1, layer 2 in vertical rows going to the left for instance. The important thing is that the arrows always point from right to left so they are not tangled. There are other ways you could assign dependencies to layers that might look better or be more informative but the "arrows always point the same way" property prevents tangling.

Layout along the other axis is a different question, I'd imagine you could shuffle the vertical order of the dependencies in the layers to minimize the number of arrows that cross or something.

The graph is already layered. It is precisely the crossings that are the problem and minimizing them does not do a lot.

Hard problem with spaghetti code, but you can try something like: http://bl.ocks.org/shunpochang/66620bad0e6b201f261c

You do not need to invoke “spaghetti code”. One file depending on lots of other files that each depend on some library headers (e.g. the standard library) results in these kinds of dependency graphs. See for example this dependency graph for a roguelike written in C: http://daten.dieweltistgarnichtso.net/pics/graphs/redo/plomr...

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