union-benchmark.py

gistfile1.py

from itertools import islice
import timeit

from shapely.geometry import Point
from shapely.ops import unary_union

def halton(base):
    """Returns an iterator over an infinite Halton sequence"""
    def value(index):
        result = 0.0
        f = 1.0/base
        i = index
        while i > 0:
            result += f * (i % base)
            i = i/base
            f = f/base
        return result
    i = 1
    while i > 0:
        yield value(i)
        i += 1

coords = zip(
    list(islice(halton(5), 20, 120)),
    list(islice(halton(7), 20, 120)) )
patches = [Point(xy).buffer(0.05) for xy in coords]

N = 100 # num of vertices
M = 100 # num of passes

print
print "N=%s" % N
print "======"
print "Binary union"
s = "u = reduce(lambda a, b: a.union(b), patches[1:], patches[0])"
t = timeit.Timer(
    stmt=s,
    setup='from __main__ import patches'
    )

print "%.2f usec/pass" % (1000000 * t.timeit(number=M)/M)
print

print "Unary union"
s = "u = unary_union(patches)"
t = timeit.Timer(
    stmt=s,
    setup='from __main__ import patches, unary_union'
    )

print "%.2f usec/pass" % (1000000 * t.timeit(number=M)/M)
print