Created
February 3, 2013 05:26
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Code for creating and testing a simple bloom filter - http://maxburstein.com/blog/creating-a-simple-bloom-filter/
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from bitarray import bitarray | |
import mmh3 | |
class BloomFilter: | |
def __init__(self, size, hash_count): | |
self.size = size | |
self.hash_count = hash_count | |
self.bit_array = bitarray(size) | |
self.bit_array.setall(0) | |
def add(self, string): | |
for seed in xrange(self.hash_count): | |
result = mmh3.hash(string, seed) % self.size | |
self.bit_array[result] = 1 | |
def lookup(self, string): | |
for seed in xrange(self.hash_count): | |
result = mmh3.hash(string, seed) % self.size | |
if self.bit_array[result] == 0: | |
return "Nope" | |
return "Probably" | |
bf = BloomFilter(500000, 7) | |
huge = [] | |
lines = open("/usr/share/dict/american-english").read().splitlines() | |
for line in lines: | |
bf.add(line) | |
huge.append(line) | |
import datetime | |
start = datetime.datetime.now() | |
bf.lookup("google") | |
finish = datetime.datetime.now() | |
print (finish-start).microseconds | |
start = datetime.datetime.now() | |
for word in huge: | |
if word == "google": | |
break | |
finish = datetime.datetime.now() | |
print (finish-start).microseconds | |
print bf.lookup("Max") | |
print bf.lookup("mice") | |
print bf.lookup("3") | |
start = datetime.datetime.now() | |
bf.lookup("apple") | |
finish = datetime.datetime.now() | |
print (finish-start).microseconds | |
start = datetime.datetime.now() | |
for word in huge: | |
if word == "apple": | |
break | |
finish = datetime.datetime.now() | |
print (finish-start).microseconds |
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