Optimize drawing plan for a polargraph

Optimize the included drawing plan map.txt:

$ time ./process.py map.txt > map_optimized.txt 
Total Glyphs: 8074
Initial penup distance:   4107485
Initial total distance:   4742961
Deduped penup distance:   3494625
Deduped total distance:   4040278
Sorted penup distance:    5319295
Sorted total distance:    5864948
Greedy penup (i=0)         124384
Greedy total (i=0)         670037

real  1m0.164s
user  1m0.088s
sys 0m0.024s

Now map_optimized.txt includes a reordered drawing plan with duplicate glyphs removed and with an improved ordering.

The optimization algorithm is basically this:

• Remove path sections which are exact duplicates of earlier sections
• Reorder paths:
  • Pick the first path as the first path in the input file
  • Find the path that starts nearest the previous one's endpoint, or the one which, if reversed, would start nearest the previous one's endpoint
  • Repeat until we have processed all paths

For the drawing plan map.txt included, this results in a 7.1x improvement in total pen travel distance (see code for definition of distance). Actual results will vary due to a variety of factors. Please report real-life results so we can include them here!

Evan Heidtmann

Olivier Bouwman