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Use a generator to generate the size list

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Way faster
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Johann Dreo 2014-04-03 23:28:22 +02:00
commit cfa38b6216
1 changed files with 7 additions and 6 deletions
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13
hull.py
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@ -1,6 +1,6 @@
import operator import operator
from utils import x,y,euclidian_distance from utils import x,y,euclidian_distance,LOG,LOGN
# Based on the excellent article by Tom Switzer <thomas.switzer@gmail.com> # Based on the excellent article by Tom Switzer <thomas.switzer@gmail.com>
# http://tomswitzer.net/2010/12/2d-convex-hulls-chans-algorithm/ # http://tomswitzer.net/2010/12/2d-convex-hulls-chans-algorithm/
@ -173,13 +173,11 @@ def convex_hull(points):
"""Returns the points on the convex hull of points in CCW order.""" """Returns the points on the convex hull of points in CCW order."""
# Increasing guesses for the hull size. # Increasing guesses for the hull size.
sizes = [] for guess in ( 2**(2**t) for t in range(len(points)) ):
for t in range(len(points)): LOG( "Guess",guess)
sizes.append( 2 ** (2 ** t) )
for guess in sizes:
hulls = [] hulls = []
for i in range(0, len(points), guess): for i in range(0, len(points), guess):
LOG(".")
# Split the points into chunks of (roughly) the guess. # Split the points into chunks of (roughly) the guess.
chunk = points[i:i + guess] chunk = points[i:i + guess]
# Find the corresponding convex hull of these chunks. # Find the corresponding convex hull of these chunks.
@ -190,11 +188,14 @@ def convex_hull(points):
# Ensure we stop after no more than "guess" iterations. # Ensure we stop after no more than "guess" iterations.
for __ in range(guess): for __ in range(guess):
LOG("*")
pair = next_hull_pt_pair(hulls, hullpt_pairs[-1]) pair = next_hull_pt_pair(hulls, hullpt_pairs[-1])
if pair == hullpt_pairs[0]: if pair == hullpt_pairs[0]:
# Return the points in sequence # Return the points in sequence
LOGN("o")
return [hulls[h][i] for h,i in hullpt_pairs] return [hulls[h][i] for h,i in hullpt_pairs]
hullpt_pairs.append(pair) hullpt_pairs.append(pair)
LOGN("x")
if __name__ == "__main__": if __name__ == "__main__":