Saturday, 26 May 2018

egg Chronology of Computer Languages 3

As one last task, I looked at producing a more traditional "flow chart" from the COCL data-set. Yet again, it turned out to be surprisingly difficult.

Sankey diagram is a close match for what I'm looking for: an ordered DAG of ancestors and descendants. But, in all the little tools I briefly looked at, the layouts of the final charts leave a lot to be desired.

I started work on a basic network layout engine in C++ but quickly came to a dead end: the number of permutations for the node positioning alone is in the order of 1e+96 which is just not tractable. And this doesn't even take into consideration the edge routing.

I finally plumped for two tools (one in C++ and the other in JavaScript) to semi-automate the layout and then continually fettled it by hand (for instance, lining up the C and Pascal families of languages vertically) until it was relatively compact.

The final result (bottom) displays the diagram using fixed-width, box-drawing characters:

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