Created
July 11, 2012 02:15
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implement dict by murmur hash
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# !/usr/bin/python | |
# -*- encoding: utf-8 -*- | |
import mmh3 | |
class MurmurDict: | |
def __init__(self, capacity = 16, load_factor = 0.75): | |
self.capacity = capacity | |
self.load_factor = load_factor | |
self.table = [] | |
for i in range(self.capacity): | |
self.table.append([]) | |
self.rate = 0.1 | |
self.size = 0 | |
def __hash_index__(self, hash_code = 1): | |
return hash_code & (self.capacity - 1) | |
def __resize__(self): | |
self.capacity = self.capacity + int(self.capacity / 2) | |
new_table = [] | |
for i in range(self.capacity): | |
new_table.append([]) | |
for item in self.table: | |
for (key, value) in item: | |
new_table[self.__hash_index__(mmh3.hash(key))].append((key, value)) | |
self.table = new_table | |
def check_size(self): | |
return self.size * 1.0 / self.capacity > self.load_factor | |
def put(self, key, value): | |
self.size += 1 | |
if self.check_size(): | |
self.__resize__() | |
idx = self.__hash_index__(mmh3.hash(key)) | |
print 'idx=%d\tsize=%d\tcapacity=%d' %(idx, self.size, self.capacity) | |
self.table[idx].append((key, value)) | |
return | |
def contains(self, key): | |
list = self.table[self.__hash_index__(mmh3.hash(key))] | |
return len(list) != 0 | |
def get(self, lookup_key): | |
list = self.table[self.__hash_index__(mmh3.hash(lookup_key))] | |
for (key, value) in list: | |
if key == lookup_key: | |
return value | |
return None | |
def size(self): | |
return self.size | |
if __name__ == '__main__': | |
murmur_dict = MurmurDict() | |
for item in range(100): | |
key = '%d' %item | |
murmur_dict.put(key, item) | |
for item in range(100): | |
key = '%d' %item | |
print murmur_dict.get(key) |
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