Personal blog on early retirement, selling tradelines, and analytics projects. I write about what I learn as I am learning it.
When I finished porting the routing engine to Python, I had a 480-line file that solved vehicle routing problems and printed results to a terminal. That’s useful exactly to me, in exactly one context. The staff scheduler had already gone through the same transition — terminal script to Flask web app — and I’d figured out the pattern there. So I assumed wrapping the VRP would be roughly the same amount of work.
It wasn’t the same amount of work. But the structure was.
The original routing model was 1,500 lines of C#. The Python port ended up around 480 lines. Some of that compression is the language — Python is more concise. Some of it is that I stripped out the proprietary cloud backend, the database calls, and the dispatch interface. What remained was the core: the model structure, the constraints, the solver parameters.
The translation itself was mostly mechanical. OR-Tools has Python bindings that mirror the C# API closely enough that you’re often just changing syntax: camelCase to snake_case, semicolons disappear, type declarations disappear. But “mostly mechanical” left room for a few things that didn’t work the first time.
Continue reading “Porting 1,500 Lines of C# to Python Without Losing My Mind”
The staff scheduler I wrote about a few weeks ago was a MILP — a Mixed Integer Linear Program. You define variables, constraints, and an objective function. Hand it to a solver, get an answer. Clean, relatively tractable, runs in seconds on a laptop.
The vehicle routing problem is something else entirely.
The app was working. On my laptop. Which is the same as not working, for most purposes.
If the goal was to keep it to myself — test it occasionally, tinker with it, update the model when I felt like it — a working local copy would be enough. But that’s not what I built it for. The point of converting these models to web apps is that they can run anywhere, for anyone, without requiring someone to have Python installed and know how to use a terminal.
So: deployment.
At some point during this project I stepped back and looked at what we’d built.
Three files. A working web application. Deployable for $7 a month. Zero web development experience going in.
That felt worth writing down.
