mileage_by_region

[yakra]

search for mileage_by_region

• 'T': Travelerlist::active_preview_mileage_by_region and Travelerlist::active_only_mileage_by_region can become a single std::unordered_map<Region*, double[2]> • fewer lookups • fewer exceptions • fewer creations NO-BUILD -- no noticeable speed increase.
• 'T': Same deal in Python, using lists or tuples NO-BUILD -- ostensible \~0.17-0.25s speedup may just be noise. Stay in line with the C++ version, with more readable code, and a cleaner commit history. Deleted branch @ ba5d725e84d2ed15940c244b5e17fcb703afd1be.
• [ ] 'G': Same for Python's 3 global active_only_..., active_preview_... & overall_... dicts • Nothing to change in C++; these data are members of the Region class. LOW PRIORITY -- between 'T' having next to no effect with 4.5x (6.74 travelers per segment * 2/3 the dict lookups) as many lookups, and 'C' having next to no effect going from 1 lookup/segment to 1 lookup/route, I don't expect much here.

• 'C': Copy the C++ approach to overall stats: Calculate subtotals per Route, then add to regional totals. Results in 1 lookup per Route instead of 1 per HighwaySegment. Naah... The difference was much less than anticipated: box	before	after
  lab1	12.7244	12.4266
  lab5	11.9216	11.2950

  (deleted stash @ bc351591af3159b764b8e07f10be7dfec4dae2bd / sulogs @ 2022-02-28.py/T3.tar.lzma) Too little IMO to justify the... distasteful, rounding needed to get t.active_systems_clinched & t.preview_systems_clinched to come out right. Even if the same is done (via a float conversion) in C++. Maybe? C++: Look into constructing & iterating thru per-region route lists. No need for region->mtx(even though speed already rounds to 0). Should be able to lose the float conversion that way. Low priority.

[yakra]

I forget what exactly happened here. IIRC Python showed no improvement. If C++ did at all, it was slight -- and was it overshadowed by #504? Spreadsheet notes aren't clear; sulogs should be in the late Feb - March 3 2022 ballpark. That's right about when I started versions.txt; does one exist?

I closed #504, then a day later marked this low priority, indicating I wasn't completely done with it. There are enough other things to tweak nearby, in particular how unordered_maps are handled, that this can wait till afterwards to see if it's any help.